Seznam abstraktů 2019: POSTEROVÁ SEKCE E

The purpose of this paper is the study of the effect of equal channel angular pressing (ECAP) on the mechanical properties of the Mg-Al2O3 nanocomposites. Originality of this work consists in the preparation of the composite systems by the method of melt-stirring. Severe plastic deformation is a useful methodology to refine the grain size to the submicron or even nanometer size. In the present work the influence of number of passes of ECAP by grain size, evolution of microstructure, mechanical properties and fracture of magnesium composites with different volume fraction of Al2O3 nanoparticles were investigated by means of optical microscopy, tensile tests and scanning electron microscopy. The grain size reduction after ECAP proved that four passes were more effective at the microstructure refining of Mg MMC. The effect of the different manufacturing processes on the yield and ultimate tensile strength and elongation at elevated temperatures was confirmed.The fracture of the as-cast AZ61 based MMCc was characterized by the brittle cleavage fracture and the ECAP-ed AZ61 alloys were characterized as the ductile fracture due to the existence of a large amount of dimples, which had a good effect on the mechanical properties improving.

The paper presents the results of research on the preparation of composites based on copper matrix reinforced with silicon carbide (SiC) contents of 0, 5, 10 and 15 wt%. Materials were compacted by one-sided pressing, followed by sintering at a temperature of 800 °C for one hour. One-sided pressing was used, with pre-set pressure of 60 kN and the rate of 200 N/s. The examinations of the composites included macroscopic and microscopic examinations (LM, SEM), XRD measurements, determination of density, hardness measurements, and a compression test. Microscopic examinations were performed using light microscopy (LM, 2D and 3D images), and scanning electron microscopy (SEM). XRD measurements were aimed to evaluate phase composition. The composites were measured using a Seifert 3003T/T X-ray diffractometer with radiation generated by a tube with a cobalt anode(λCo= 0.17902 nm). X-ray examinations were performed, with the measurements based on the symmetric Bragg-Brentano geometry. The computer software and the DHN PDS crystallographic database were used for phase identification. Hardness measurements were made using the Brinell method. The test results showed that the optimal content of silicon carbide in Cu / SiC composites is 10 %.

The surface of Nimonic 80A alloy was melted and rapidly solidified using TIG process (Tungsten Inert Gas) in order to produce a high-strength microstructure to improve cavitation erosion resistance. Cavitation tests, performed on an ultrasonic vibrator at a frequency of 20 kHz and at amplitude of 50 μm oscillations pointed out that these microstructure changes lead to significant differences in the behavior of this alloy to erosion generated by vibrator cavitation. Optical microscopy and scanning electron microscopy of the TIG melted sample surface and tested for cavitation erosion, showed a ductile behavior. At the same time, the finishing of the microstructure is showing a significant decrease of the maximum erosion penetration depth and of the erosion speed compared to the reference material.

Phase formation and its correlation with magnetic properties of the powders Fe2O3 + FeO mechanically alloyed with RE oxides: Pr2O3 and Dy2O3 in an inert Ar atmosphere followed by subsequent annealing were studied. The composition can be described as [90% (Fe2O3 + FeO) + x % R2O3], where x = 0, 10; R = Pr, Dy. It was shown that despite the presence of the Fe3O4 phase in an amount of ~ 80 % in the powders after 15 hours of mechanical milling without adding R2O3, specific magnetization (σs) of the powders in a 1600 kA/m (20 kOe) field has values about 50 A×m2/kg, which is significantly lower (by ~ 45 %) than the calculated specific values magnetization for a given composition. After the isothermal annealing of the powders for 30 minutes, as a result of a larger Fe3O4 phase amount formation (more than 90 %), the specific magnetization σs and specific residual magnetization σr grow and have a curve with a maximum at 500 °С. As the annealing temperature further increases, the specific magnetization of the powders decreases in accordance with the decrease of the Fe3O4 phase amount. After annealing in the range of 200-500 °C, the amount of Fe3O4 in powders is maximal (higher than 90 % vol.). The only process that occurs after 200-500 °C annealing is the RFeO3 formation with some decrease in the amount of Fe3O4. It leads to a significant increase in both the magnetization σs, σr and coercivity Hci, instead of reducing them as the Fe3O4 amount drops. It can be assumed that this fact can be related to the processes occurring in the Fe3O4 phase at the atomic level of interactions, doping Fe3O4 with RE ions by implementation into its lattice. This can be a promising method to obtain a doped Fe3O4 contrast agent by RE atoms, which can be used in MRI investigations.

Parts from heat-resistant nickel alloys with directional crystallization, as well as single crystals are used in engines and power plants operating under conditions of high temperatures and loads. In this paper, the study of the structure formation in the process of selective laser melting of a heat-resistant nickel alloy was conducted. It is obtained that the length of the forming grains considerably exceeds the thickness of one build layer. The results of the influence of the technological parameters of the selective laser melting process on the directionally crystallized structure characteristics are shown. Elongated grains oriented along the growth direction. The composition, structure, and properties of the obtained samples were studied.

In order to create a high-quality coating of titanium and its alloys, it is necessary to ensure perfect gas protection of the bath from the effects of air oxygen. Inert gases such as argon or helium with a purity of 99.999% are used. Gas protection must be maintained until the temperature drops below 300 °C. If the protection is not good enough, there is an undesirable reaction with oxygen, to reduce the mechanical properties and to discolor around the weld. The paper presents a procedure for the preparation of a welding jig for the welding of titanium and other sensitive materials by the plasma welding (PTA) method. Manufacturing processes and subsequent surfacing are described. The aim of the paper is to create a functional product that provides sufficient protection for the entire process of surfacing sensitive materials.

This article describes mechanical properties such as tensile strength, yield strength, impact resistance and correlation between conditions determining the breakthrough and nature Fe40Al5Cr0.2TiB alloy. The breakthroughs obtained during the tests of mechanical properties were carry out by scanning electron microscopy (SEM). Insufficient plasticity at ambient temperatures and a tendency to brittle fracture make the material vulnerable to brittle fracture, and breakthroughs in areas with plastic deformation differ by their morphology from the ductile fractures found in conventional construction materials. The intention of the authors was to classify the breakthroughs of FeAl intermetallic alloys based on the mechanism of their formation.

γ-TiAl based alloys are very perspective materials thanks to their outstanding properties, such as high specific strength, low density, high modulus of elasticity, good oxidation resistance and resistance to creep. At present, the greatest attention is paid to TiAl alloys which contain relatively high content of refractory metals such as Nb, Ta, Mo and W. The main objective of this paper is, how to transform the refractory W, Ta or Nb into the form of master alloys, suitable for preparation of heavy alloyed γ-TiAl intermetallic alloys and characterize the homogeneity, microstructure and other properties (oxygen content, melting temperature) important for their further using.

Hydrogen storage (HS) performance of three Mg-xIn-yCB alloys (CB - amorphous carbon, x = 55, 64, 73; y = 10 wt. %) was studied. Indium concentration covered an area of ordered β structures. Alloys were prepared by ball-milling in hydrogen atmosphere. Kinetic curves and PCT isotherms were measured in the temperature interval from 200°C to 325°C. X-ray diffraction spectroscopy (XRD) was used for structure investigation. Alloy with x = 73 wt.% In (β’’ structure) showed reversible amorphization during temperature cycling between about 100 °C and 350 °C. Hydrogen sorption experiments were done by the Sieverts method under the hydrogen gas pressure ranging from 0.1 MPa to 2.5 MPa. It was found that hydrogen sorption capacity varied between 0.47 and 1.1 wt. % H2. Hydride formation enthalpy ΔH calculated from desorption PCT experiments was significantly lower than ΔH, known for pure Mg. This invoked an idea that atomic order of Mg-based HS materials might decrease the high thermodynamic stability of hydride phase.

The effect of hydrogen atmosphere sintering in manufacturing (Sm,Zr)(Со,Cu,Fe)Z-based permanent magnets on their properties has been studied. It is shown that sintering in hydrogen, in comparison with sintering in argon, allows obtaining a higher density of billets, while reducing the optimal sintering temperature range by 20 °C. To achieve the same levels of intrinsic coercivity, hydrogen sintered samples require 1.5 times less time of isothermal aging, at the same temperature of heat treatment. In the end, (Sm,Zr)(Со,Cu,Fe)Z-based permanent magnets of standard chemical composition sintered in a hydrogen atmosphere, in comparison with sintered in argon, are characterized by higher hysteresis performances: remanence, induction coercivity, intrinsic coercivity and static energy product.

As an example of the experimental Al6Ca1Fe alloy of eutectic composition, the fundamental possibility of using alloys based on aluminum-calcium eutectic to produce castings using high pressure die casting is substantiated. As a result, high-quality castings of a flat section with a width of 15 mm and thicknesses of 1.9, 2.8, 5.1 and 6.5 mm were obtained. Analysis of the microstructure of the obtained samples showed that, in comparison with AlSi12 silumin, the eutectic composition (A04130) of the structural components of the Al6Ca1Fe alloy have a finely dispersed structure. The presence of primary crystals of the phases containing calcium and iron was not detected, which suggests that both elements were fully incorporated into the eutectic, whose composition corresponds to 9.2% Ca and 1.7% Fe. In addition, it was found that not only the phases from binary systems (Al4Ca and Al3Fe) can be in equilibrium with the aluminum solid solution, but also the Al10CaFe2 ternary compound, on the basis of which a fragment of the Al-Ca-Fe phase diagram is presented in an aluminum rich area. In particular, the structure of the liquidus surface was proposed, two three-phase regions (Al) + Al4Ca + Al10CaFe2 and (Al) + Al10CaFe2 + Al3Fe were identified, and the presence of two nonvariant reactions was established: the eutectic L → (Al) + Al4Ca + Al10CaFe2 and the peritectic L + Al3Fe → (Al) + Al10CaFe2. Mechanical properties were also investigated by tensile testing. The obtained values of the UTS averaged 25 % more than that one of standard alloy AlSi12. ACKNOWLEDGEMENTS: The work was supported by the grant of the RNF (agreement No. 14-19-00632-P).

Literary research of high-temperature materials, overview of used materials. Molybdenum and its alloys, properties, possibilities of the application in the vacuum technique, electrotechnics and electronics. Methods of preparation of molybdenum alloys even in the monocrystalline form (plasma metallurgy and electron beam zone melting). Evaluation of micro-structural (optical microscope, scanning electron microscope), chemical (optical emission spectroscopy, x-ray and EDX analyses) of Mo-Ta, Mo-V and Mo-Ir alloys. Distribution of iridium in molybdenum by electron beam zone melting, dislocation and cellular substructure in molybdenum single crystals, application of autoradiography.

The achievements of modern surface engineering can be applied in many areas. With modern engineering materials and manufacturing techniques, the comfort and safety of life of road users and other people present on the road have substantially improved. The road infrastructure includes street lighting, which uses modern lightweight materials from the group of non-ferrous materials or composites. Their surface is covered by various surface layers in order to improve functional properties of the finished part. This paper presents an analysis of the structure and functional properties of coatings used for street lighting columns, which have recently become very popular.

Metallic-ceramic composites are considered as materials with functional properties depending on the production methods. In this work, bi-layered composites Ti6Al4V/Al2O3 were obtained using the spark plasma sintering (SPS) technique. The powders (Sulzer Metco) of titanium alloy Ti-6Al-4V with a spherical shaped particle and aluminum oxide (Metco 101SF) with an irregular shaped particle were used. The specimens were compressed at 20 MPa and sintered in a shielding gas (argon) medium at the temperature of 1200 °C in an SPS HP 5 for 25 min. The obtained composites were subjected to microstructural analysis using light microscope, scanning microscopy Joel JSM 5400 equipped with EDS. Hydrostatic weighing in deionized water according to the PN EN standard was used to evaluate the relative density.The results showed that hot pressing proces (SPS method) could be used to produce dense bi-layered composites with proper interface properties between Ti6Al4V and Al2O3.

In this article, the microstructure of AZ91C magnesium alloy castings produced by investment casting was investigated. Castings were studied in as-cast state and after T4 and T6 heat treatment. The identification of all phases in microstructure was carried out using a scanning electron microscope (SEM) with energy dispersive X-ray spectroscopy (EDS) analysis. The influence of cooling rate after casting, temperature of solution annealing, temperature of artificial aging and cooling rate after heat treatment on the microstructural characteristics such as secondary dendrite arm spacing (SDAS) or grain size was studied. The SDAS analyses were carried out using a light microscopy with the subsequent image analysis. Except of Mg-Al solid solution and Mg17Al12 precipitates, the microstructure contains other phases based on Mg-Si and (Al,Si)-Mn in globular or needle morphology. The SDAS in as-cast state was measured and was of tens of micrometers, but after T4 heat treatment, the gran size exceeded 100 µm and the Mg17Al12 phase was still undissolved along the grain boundaries in samples with thicker wall dimension. After T6 heat treatment, continuous and discontinuous precipitates of Mg17Al12 phase were formed, most of them were nearby the grain boundaries proving the inhomogeneous distribution of Al atoms in solid solution after T4 heat treatment.

High energy ball milling is a powder processing method in which the powder particle size can be decreased to micrometer size in a relatively short period of time. This method is based on the friction and the high energy kinetic collisions between the balls and the trapped powder particles. The milling process is influenced by many process variables such as mainly the rotational speed, ball to powder weight ratio and processing time. In the present study, high energy ball milling process was performed for molybdenum powder using a high energy ball mill under different milling conditions varying the: (i) rotational speed from 600 to 800 rpm, (ii) ball to powder weight ratio of 100:3 and 100:6, (iii) milling time in the range of 10 to 60 minutes, (iv) process control agent using polyethylene glycol, and (v) milling atmosphere under air or nitrogen. The used initial molybdenum powder was of globular morphology and 100 µm in particle size. The powders after milling were characterized by a scanning electron microscope (SEM) and a laser diffraction size analysis. The particle size of milled powders was decreased down to 1.1 µm. As the most effective ball to powder weight ratio was found 100:6 with the milling speed of 800 rpm. The milling time played a crucial role for the refinement of particles up to 45 min, where the further milling had negligible effect on the overall trend of particle size evolution.

In the recent years, the amount of waste has been drastically increasing, affected on the environment. On the other hand, there is observed a shortage of metals associated with the increase in their use and depletion of their natural resources. NiMH batteries. NiMH batteries contain, among nickel, cobalt, lanthanum, neodymium and other important metals. One of the possible and effective methods used for the metals recovery are hydrometallurgical processes, i.e. leaching and solvent extraction for metal separation. This work presents the results of the Zn(II), Co(II), Ni(II), La(III), Ce(IV) separation by solvent extraction. The source of metals was the solution from leaching of NiMH batteries. In the extraction process, chosen organic acids like, bis(2,4,4-trimethylpentyl) phosphinic acid (Cyanex 272), bis(2,4,4-trimethylpentyl)ditiophosphinic acid (Cyanex 301), bis(2,4,4-trimethylpentyl)tiophosphinic acid (Cyanex 302) and di(2-ethylhexyl)phosphoric acid (D2EHPA) were used as the extractant.

The Nb-Si in-situ composite was synthesized by binder jetting additive manufacturing technology. The Nb powder was used as the raw material. The green model was printed with binder in a layer-by-layer way and then infiltrated with liquid Si during in furnace. The microstructure consists of NbSi2 and excess silicon. To control the Si content a mixture of Nb-16Si (at%) was used as a raw material with subsequent melting of internal silicon in the furnace. As a result, the microstructure consists of Nbss, Nb3Si, NbSi2 phases.

The powder of Nb-25Ti-2Cr-2Al-16Si (at%) was obtained by mechanical alloying and plasma spheroidization from elemental powders. The building was performed by SLM 280HL machine on the titanium substrate. The microstructure was analyzed by MIRA Tescan scanning electronic microscope. The XRD was performed by BRUKER D8. The microstructure consists of Nbss+Nb3Si eutectic with several areas of coarse dendrites, corresponds to the Nbss. The microstructure is greatly refined in comparison with casting technologies like VIM.

The present work is focused on the synthesis and mechanical properties evaluation of non-equiatomic Hf0.5Nb0.5Ta0.5Ti1.5Zr Refractory High-Entropy Alloy (RHEA). For the alloy production, a combination of mechanical alloying (MA) process in a planetary ball mill and hot pressing (HP) for powder densification was utilized. The effect of different sintering temperatures was explored in a temperature range of 1200 °C up to 1600 °C. The bulk material was then subject to investigation in terms of its microstructural features, elemental and phase composition and basic mechanical properties by scanning electron microscopy (SEM), X-ray diffraction (XRD), as well as hardness testing, density determination by Archimedes’ principle. The results show that very hard fine grained bulk materials were achieved in all microstructures, with an average hardness of (784 ± 5) HV0.2, (793 ± 3) HV0.2 and (814 ± 5) HV0.2 for the sintering temperatures of 1200 °C, 1300 °C and 1600 °C respectively. The slightly minimum increase in hardness might be attributed to the partial dissolution of a second-phase triggered by the increase in temperature.

Under the pressure of 0.4-0.5 bar, the purification experiment of Mo by Ar and Ar-20%H2+Ar plasma arc melting (HPAM) was operated. The experimental results show that the purity of Mo increased from 99.98% to 99.9994% when the plasma gas was argon. However, the purity of Mo increased from 99.98% to 99.9997% when plasma gas was Ar-20%H2. It suggests that the rate of impurities removal by HPAM was enhanced by adding hydrogen. Based on the thermodynamic analysis, hydrogen in plasma decomposed into hydrogen atoms, which reacted with impurities to hydrides vapor. The impurities were removed easily by hydrides vapor. From kinetic analysis, the rate of impurities removal by HPAM was accelated by elevating temperature. The temperature is raised by the addtion of hydrogne, which has high thermal conductivity.

Polycristalline aluminas were studied. These materials characterized by the mechanical point of view (friction and wear) and dielectric breakdown. The comparison of these various results shows that, for all these properties, the grain size and also, the nature of the secondary phases and the microstructural parameters were the most significant.
Moreover, from the tribological point of view, the dielectric characteristic of materials (breakdown strength) has a fundamental role in the creation of agglomerated wear debris (“third body”) and its properties: a finely agglomerated third body will be obtained for high breakdown strength. Such third body will be able to protect the substrate and thus to reduce later wear. In the same logic a correspondence between breakdown strength and toughness was established, thus confirming the existence of mechanical-electrical correlation for non-conductive materials.

This study has been focused on the evaluation and comparison of the chemical treatments applied (aqueous solutions of CH3COOH (1 %), CH3COONH4 (5/25 %), EDTA (3/5 %), HCl (5/10 %) and ion exchange resin) or possible applicable (H2SO4, Na3PO4·12H2O or KNaC4H4O6·4H2O) to the heritage of lead stored in museums. The evaluation of the different solutions used for chemical treatment on lead samples is based on lead surface changes (colour, morphology, chemical composition) observation and on the impact of the chemical treatments (mass loss and cleaning efficiency). Examination of the lead samples before and after different chemical treatments showed that each of used solutions induced any chemical and/ or physical changes.

Tantalum rich ores containing oxidic minerals like tantalite or columbite are primarily mined by artisanal and small scale practice in countries around the African Great Lakes like Congo and Rwanda. Concentrates with a Ta2O5 content higher than 25 % are directly processed via leaching and liquid-liquid extraction whereas recycling, chlorination and processing of low grade residues, slags, sludges or dusts represent aspiring alternatives accounting for approximately 30 % of the tantalum world production. The pyrometallurgical manufacturing of synthetic tantalum concentrate (syncon) in a multi-stage process represents an established procedure for various input materials. Within this study the first step (smelting and reduction) is recreated in a small scale induction furnace and the metal/slag separation, analysed via REM/EDX and XRF, for evaluation of an ingot produced throughout four smelting phases. Huge amounts of high melting slag comprising mostly Al2O3, CaO, MgO, SiO2, TiO2 and ZrO2 arise whilst Nb2O5 and Ta2O5 concentrate in the iron phase. Further process optimizations for instance by adjustment of treatment time, tapping procedure, enhanced amount of iron collector phase or usage of low melting additives are necessary to attain industrial standard slag composition of < 0.2 % Ta2O5. However, accumulation of value components was successfully realized at 1600 °C. Therefore, yield and energy saving potential for the syncon production process can be investigated in laboratory scale.

The β titanium alloys are promising candidates for biocompatible implant applications because of their low Young modulus when compared to (α + β) titanium alloys. In this study three β titanium alloys Ti-12Mo-6Zr, Ti-8Mo-6Zr-2Ta-2Sn and Ti-8Mo-6Zr-2Ta-4Sn (in at%) were prepared by plasma metallurgy method. Melted ingots were submitted to homogenization at 950 ºC for 35 hours by means of vacuum high temperature furnace followed by furnace cooling under argon atmosphere. Subsequent heat treatment consisted of solid solution annealing at 900 °C for 1 hour under flowing argon with following water quenching. The phase analysis of the microstructure was performed using optical and scanning electron microscopies. The analysis was completed by EDX measurement that confirmed the β grains and α precipitates contained in the microstructure. Specimens of all three prepared alloys were subjected to microhardness testing to evaluate the influence of different thermal treatment. It was concluded that the solution treatment and water quenching promoted increase in the microhardness of Ti-12Mo-6Zr alloy whereas for developed Sn doped alloys the microhardness values remained the same.

The current trend is to fabricate aluminium gallium nitride based devices due to the high energy gap, high breakdown field, and saturation velocity of (GaN) for high-power amplifiers and high-frequency applications. This paper presents a newly developed compact model for input- output gate field-plated (FP) High Electron Mobility Transistor (HEMT) based on AlGaN/GaN heterojonction which incorporates an AlN ceramics substrate, taking into account the effects of spontaneous and piezoelectric polarizations on sheet carrier concentration.
The AlN ceramic substrate is used to improve the thermal conductivity of the FP-HEMT devices. The proposed structure incorporates also a spacer layer of AlN to counter the decrease in mobility due to increasing 2-DEG (Two-Dimensional Electron Gas). Results showed that optimized FP design allows to considerably decreasing an electric field peak near gate edge towards drain electrode which enhance the breakdown voltage and decrease the reverse leakage current of HEMT devices. The proposed model provides the complete set of analytical equations that relate the physical design parameters to the electrical characteristics of the proposed device for high frequency, high-voltage and high-power applications such as radar and wireless communication systems

Samples of in-situ TiAl-based matrix composite reinforced with Ti2AlC particles were prepared by centrifugal casting of Ti-47Al-5Nb-1C-0.2B (at.%) alloy. The as-cast samples were subjected to hot isostatic pressing (HIP) at 1360 °C to remove casting porosity. The applied HIP conditions resulted in a significant coarsening of as-cast grain structure connected with deterioration of mechanical properties. Two multi-stage heat treatment routes were proposed to refine the coarse grain structure of the HIP-ed samples. The pretreatment of the composite in single α phase field followed by air cooling (AC), oil quenching (OQ) or water quenching (WQ) leads to the formation of massive γM(TiAl). The consequent annealing in the γ(TiAl) phase field followed by a stabilisation annealing at 900 °C leads to the formation of homogeneous fine-grained γ type of microstructure in the OQ and WQ samples. The solution annealing of the OQ and WQ samples in the α phase field followed by slow cooling results in the formation of refined equiaxed grains with nearly lamellar α2(Ti3Al) + γ microstructure. The contribution of several mechanisms to the grain refinement is analysed and discussed.

Ti-22Al-25Nb orthorhombic alloy is considered to be an advanced intermetallic alloy for high-temperature applications. In this paper, the effects of Hot Isostatic Pressure (HIP), homogenizing annealing and aging in different phase regions on microstructure and microhardness of the Ti-22Al-25Nb alloy obtained from elemental powders by Selective Laser Melting (SLM) were studied. HIP allowed to reduce the residual porosity in the samples, however high-temperature annealing was needed to dissolve Nb particles and obtain a homogeneous microstructure. Differential Scanning Calorimetry was used to determine phase transition temperatures in the fabricated alloy and allowed to choose appropriate aging temperatures. Aging of the alloy resulted in the formation of intermetallic Ti2AlNb and Ti3Al phase depending on the temperature.

In the present work, compact of Cu matrix composites reinforced with 5 wt% of TiN were prepared by mechanical alloying and spark plasma sintering method. Influence of sintering parameters on the electrical, mechanical, physical properties and microstructure of copper matrix composite material was investigated. From the results of the measurements, it follows that within the entire investigated temperature range, the density, hardness and electrical conductivity of copper-TiN composites change according to the temperature consolidation changes. It was determined that structure properties and density of sintered material have direct relations to electrical conductivity. Based on the study, it could be concluded that homogeneous distribution of reinforcement phase and maximize reduction of porosity in sintered material should have an impact for electrical conductivity of Cu matrix composites made by powder metallurgy route. A composite of copper and TiN particles reinforcement was prepared by mechanical alloying and consolidated by spark plasma sintering under different temperatures. Electrical conductivity and hardness of the composites change with the temperature of consolidation.

In this paper, Ti-48Al-2Cr-2Nb (at. %) gamma-based alloy spherical powders were prepared by mechanical alloying of elemental powders and plasma spheroidization. Microstructural features and phase composition of the obtained powders were studied after different time of mechanical alloying in a planetary mill to investigate the alloy formation. After determining optimal milling parameters allowing to obtain powders with a fairly homogeneous microstructure and composition, the powders were treated in the flow of a thermal plasma to produce powder particles with a high degree of sphericity. The produced spherical powders were investigated using Scanning Electron Microscopy and X-Ray Diffraction. The study showed the feasibility of the suggested approach to fabricate spherical homogeneous powders of gamma-based intermetallic alloy for its application in Additive Manufacturing processes.

The mathematical modeling of the behavior of a group of industrial aluminum alloys with the initial varying grain structure exhibiting superplastic properties in certain temperature-strain rate ranges is presented. Used the definition of “dynamic superplasticity” emphasizes the hierarchy of states, which occurs in the material from the source various-grained structure in a changing temperature and speed conditions. The dynamic superplasticity of such alloys is considered from the standpoint of the theory of nonequilibrium phase transitions as a phenomenon that occurs under the conditions of nonequilibrium excited fine-grained dynamic structure with the appearance of an amorphous state of grain boundaries that stimulates grain boundary slippage. The analysis of mechanisms of superplastic deformation is carried out on the basis of a model representing the relationship between stresses, temperature and kinematic characteristics. The energy function of the state is considered in the form of an assembly catastrophe potential. In the framework of the mathematical model, an analytical expression for the sensitivity function of the material to structural transformations is proposed. In particular, for the considered industrial aluminum alloys with the initial multi-grain structure, such an irreversible transition is dynamic recrystallization, during which the grain is crushed and the structure becomes fine-grained. The interrelation of the obtained expression with the evolutionary equations of the model describing the laws of deformation of alloys in wide temperature-rate ranges, including superplasticity, is shown. Comparison of the obtained theoretical and available experimental data was carried out for the alloy AlMg5.

The recrystallization behaviour of a twin roll cast ZAX210 alloy has been investigated under deformation conditions equivalent to the hot rolling process of magnesium strip. A set of strain levels, beginning at the critical strain for the onset of dynamic recrystallization has been studied. The dynamic recrystallization taking place during hot deformation of the magnesium alloy ZAX210 was analysed by plane strain compression tests together with optical microstructure investigation. The volume fraction and size of dynamically recrystallized grains increased with increasing strain. With equal strain the dynamically recrystallized volume fraction rises with higher deformation temperatures as well as lower strain rates. Furthermore, it has been found that the deformation temperature plays a major role, rather than the strain rates, in the activation of dynamic recrystallization processes during deformation. The results were used to identify the coefficients for the JMAK-model approach on the dynamic recrystallization of the ZAX210 twin roll cast strip.

The spark plasma sintering (SPS) method was used to prepare bulk materials form WN43 magnesium alloy atomized powder. Compression tests were carried out in order to investigate the effect of different sintering regimes (10 min at 400, 450, or 500 °C) on the mechanical properties of the material. Furthermore, complementary in-situ acoustic emission (AE) recording was employed to reveal the dynamics of deformation processes during compression. It was shown that by increasing the sintering temperature, the ultimate compressive strength and ductility were significantly improved. The AE data and microstructure observations suggest that pronounced twin nucleation takes place around the yield point whereas twin growth and dislocation activity are the dominant deformation mechanisms in the later stages of deformation.

In the present work hot rolled AlZnMgCu alloys with and without Sc,Zr addition were studied. First, the temperature and time of annealing of hot rolling was looking for. Then, precipitation reactions of hot rolled alloys were studied by differential scanning calorimetry and microhardness measurements during annealing from room temperature up to 450 °C. These measurements were compared to microstructure development that was observed by scanning electron microscope and by electron backscattered diffraction. The grain size was ~ 20 μm in the AlZnMgCuScZr and ~ 1000 μm in the AlZnMgCu alloy. Microstructure observation proved eutectic phase at (sub)grain boundaries. Primary multilayer Al3(Sc,Zr) particles also precipitated during casting and subsequent cooling in the alloy with Sc,Zr addition. These particles were observed in the alloy with Sc,Zr addition after annealing up to 450 °C, too. In the DSC curves the exothermic process at ~ 200 °C was observed. Activation energy of the process was calculated. There were observed constant values of microhardness (in accuracy of measurements) during annealing up to 450 °C. Higher microhardness values were measured in the alloy with Sc,Zr addition.

The use of aluminum for car bodywork is a new trend in the automotive industry. But joining of aluminum carries a number of problems, such as pores, cracks and other internal defects. For joining of thin sheets, pressure welding is mainly used in the automotive industry. For example, spot resistance welding (RSW) or capacity discharge welding (CDW) can be used. The paper describes the influence of the parameters of CD welding on the size of the weld nuggets and the quality of the joint from the aluminum alloy EN AW 6016.

Laminated CuAl10Fe3Mn2-intermetallic phases composites have been produced in vacuum through reactive bonding at 875 °C using bronze and titanium foils with thickness 0.6 and 0.1 mm, respectively. During fabrication the titanium layers reacted completely and formed Ti2Cu, TiCuAl and TiCu2Al intermetallics. This paper summaries the microstructural changes which take place in laminated composites during heat treatment. Also the mechanical properties and fracture behavior of the heat treated composites were examined through hardness measurements and tensile tests. The results of investigations indicated that tensile properties of the composites strongly depended on the type of applied heat treatment (especially on aging temperature). Upon completing examinations one can define the heat treatment conditions necessary for obtaining optimum properties of laminated CuAl10Fe3Mn2-intermetallic phases composites.

Micro mechanisms belong to innovative solutions used in many branches of industry, ranging from aviation and cosmonautics, through the automotive and medical industries. The manufacturing of micro and nanostructures requires the use of precision machining. An important role in manufacturing micro parts has electrical discharge machining (EDM). Micro - EDM is a nonconventional method of removing material, using the phenomenon of electric discharges occurring between two electrodes in the presence of a dielectric. Application in the process working electrode in the form of a thin wire (0.1 mm) allows cutting complex shape microelements. The paper presents the result of the micro wire electrical discharge machining of titanium alloy Ti-6Al-4V. Response surface methodology (RSM) was used to build empirical models of the influence of pulse time ton, wire tension WT, wire speed WS on the roughness Ra and the cut speed V during machining titanium alloy Ti-6Al-4V.

The article aims at the use of lightweight aluminum alloy decks in bridge engineering and presents the advantages of their increasing application. The article also highlights the properties affecting the durability and compressibility of aluminum alloys. Next, the article covers the assets of the aluminum alloy box-section decks. Low weight, durability, resistance to operating conditions, fatigue life and ease of geometric shape design are the virtues that made them more commonly applied for bridges and footbridges. Difficult operating conditions and the complexity of stresses, the requirement for frequent inspections and maintenance, the diversity of dimensions as well as geometric and structural solutions in bridge engineering are behind the search for the latest solutions. Bridges, as strategic structures designed for transportation, forwarding and logistics, also require minimisation of traffic problems in the event of a lane shut-down for the time of repair. The use of prefabricated aluminum decks reduces load, time and energy consumption and improves working methods. The functional and light aluminum alloy decks, combinable with a durable polymer surface, create new possibilities for the shape design of the existing upgraded bridges. Overcoming the limitations of concrete and steel supporting structures allows replacing, enlarging, widening or even adding new road lanes. The environmental aspect of the use of recycled materials in production has also been raised here. The article presents concrete examples of renovation of the existing wooden, steel and reinforced concrete bridge structures with alternative aluminum alloy decks.

Iron is present in nearly all aluminum alloys as an impurity causing a formation of iron-rich precipitates in the as-cast state of the alloy due to its low solubility in the matrix. Dispersion, morphology and relative coarseness of precipitates may affect formation of unwanted pinholes during cold rolling to thin gauges. When used as foil stock these pinholes may negatively affect utility of the foil. Heat treatment may be employed during down-stream processing to influence distribution of the precipitates. An impact of a high temperature annealing on iron-rich precipitates in a twin-roll cast EN-AW 8006 alloy was investigated. Electrical resistivity measurements with a heating rate simulating industrial annealing was performed to determine phase transformation temperatures. In-situ electron microscopy annealing was employed to directly observe mictrostructural transformations in the selected temperature intervals.

The experiment described in this article deals with the comparison of structures and mechanical properties of the Mg-4Y-3RE-0.5Zr (WE43) magnesium alloy produced by three different methods. A technique of additive manufacturing, selective laser melting (SLM), is compared with two conventional manufacturing techniques, casting and extrusion. Microstructures and chemical composition of present phases were studied using scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDS). Mechanical properties were compared based on hardness measurement, compression test and three-point flexural test. Significant differences were found between the microstructures of WE43 alloy produced by different production processes. Measurements of mechanical properties showed similar mechanical properties of additively manufactured samples with as-cast samples.

Generally, the recovery of valuable components from spent hard metals comprises a necessity for Europe. China dominates the tungsten market by a share of about 80 % of the world wide annual production. The strong price fluctuation of the most important intermediate (APT - ammonium paratungstate) in the last decade displays its market power. Naturally, recycling offers a possibility to reduce the dependency and provide a secure source of commodities. Currently, the conception of a semi-direct recycling technique is fairly unknown on industrial scale in comparison to the two main routes (direct and indirect reclamation). However, the idea of semi-direct recycling features some interesting advantages. For instance, the direct reuse of the milled carbide skeleton and the separate recovery of the binder metal(s) (commonly cobalt) can reduce the energy consumption and generate a lower environmental impact. Additionally, depending on the leaching agent, a partial decoating of the substrate offers an extra bonus. In continuation, a characterization of the process schema as well as possible chemical reactions displays the benefits to the state of the art.

The use of modern technologies, such as 3D printing techniques, creates the possibility of easy and rapid prototyping, being an important element in the design of technological processes. This modern process of elements producing of any shape consists in adding layer by layer of structural material. This is a lossless production, which is an additional advantage compared to conventional technologies such as CNC machining. The paper presents the results of research on the change in strength of samples made in 3D printing technology in the FDM (Fused Deposition Modeling) technique [1], depending on the method of printing and the percentage filling of the layer. The material used for printing was PLA (polylactide). Flat samples with dimensions 150x20x4 mm were printed using the XYZprinting da Vinci 3D printer localized in the Faculty of Production Engineering and Materials Technology at the Czestochowa Technical University. The produced samples were tested in a static tensile test. The research allowed to determine the impact (quantity / method / type) of the filling, and thus the amount of material used and the time of printing, on the strength of tested material. The presented results will enable the selection of optimal printing parameters in order to obtain the expected strength of the parts printed in the FDM technique.

The as-cast commercial Al-6 wt% Zn-2.5 wt% Mg-1.3 wt% Cu-0.8 wt% Fe, Si, Cr (AA7075) and AA7075-ScZr (0.19 wt% Sc-0.06 wt% Zr) alloys were investigated during isochronal annealing from room temperature up to 450 °C. Precipitation reactions were studied by microhardness, conductivity measurements and differential scanning calorimetry. Microstructure observation by scanning electron microscopy and transmission electron microscopy proved the Zn, Mg, Cu-containing eutectic phase at grain boundaries in the as-cast state of both alloys. The melting of this eutectic phase was observed for both alloys at ~ 480 °C in the DSC curves at heating rate of 20 K/min. The distinct changes in microhardness and conductivity curves as well as in heat flow of the alloys studied are mainly caused by dissolution of GP zones and by formation of the metastable phase particles of the Al-Zn-Mg-Cu system. The hardening effect after isochronal annealing at temperatures above ~ 270 °C reflects the Sc, Zr-addition in the AA7075-ScZr alloy - the secondary Al3(Sc,Zr) particles precipitation causes a pronounced hardening in the temperature range of 270-450 °C. The eutectic Zn,Mg,Cu-containing phase partly disappeared after the isochronal annealing at 450 °C as it was observed by scanning electron microscopy.

The paper deals with methods of cleaning metal sponge castings. This type of metal foam materials, which is unique amongst other types by having fully interconnected and open pores, is produced by a two-step investment casting process using an evaporative polyurethane pattern. A special gypsum compound is used as a mould making material that is able to completely fill the complex pore system during moulding. However, after casting, the moulding material has lower collapsibility (higher residual strength). For this reason, there is a problem with the removal of mould residues from individual pores. Therefore, various alternative methods of cleaning this type of casting have been designed and tested in the experiment.

For several years, continuous technological progress has been observed, resulting in a constantly growing number of e-waste. The diversified composition of e-waste causes the emergence of a large amount of hazardous waste, which is a threat to both health and life of people, as well as the environment. Nowadays, effective recycling of this type of waste has been recognized as a major challenge for every society. Spent printed circuit boards (PCBs) that are part of most electronic devices, including mobile phones and computers contain many metals. Printed circuit boards cause not only ecological threat, but also serious waste of resources, including copper. That is why new and effective ways to process these wastes and re-use of recovered metals are increasingly investigated. Interest in hydrometallurgical processing of used electronic equipment has increased in recent years due to its advantages - it is more accurate, more predictable and easier to control compared to pyrometallurgical methods. This method does not require the use of complicated and expensive devices. There are many leaching reagents that allow the dissolution of metals. Among the appropriate leaching agents, acids such as H2SO4, HCl and HNO3 can be distinguished. Literature data show that a strong oxidizing agent should be used to increase the efficiency of the leaching process. This is justified by presented in the literature results of leaching with the addition of hydrogen peroxide and ozone. Own research confirms that among the best leaching agents the best results of copper leaching from electronic waste were obtained for H2SO4 and HCl, especially when the oxidizer in the form of hydrogen peroxide and ozone was added to the process. These conditions favor the dissolution of metals. The conducted research indicates a large potential of the PCB leaching method using HCl and H2SO4 with the addition of oxidants such as H2O2 or O3.

Aim of this work is to test possibility to utilize colorimetric spectroscopy for monitoring the corrosion of lead and tin-lead alloys. And furthermore method suitability for preliminary corrosion evaluation of cultural heritage objects. According to literature colorimetry is used to monitor patinas of bronze objects, thus the method might be also suitable for lead based alloys. Samples used were made from commercially produced lead plate. These were exposed in the climatic chamber to different relative humidity (60, 80, 90 %). After the exposure the corrosion products with different color formed on sample surface. These corrosion products were evaluated by different methods: optical microscopy, colorimetric spectroscopy, and X-ray chemical analysis. Collected colorimetric data display difference between treatments suitable for patina evolution monitoring. The paper presents obtained results and comparison of applied methods.

Some recycling technologies are used to processing of waste lithium batteries. The treatment can be carried out pyro-metallurgically, hydro-metallurgically or both with respect to which metals must be obtained. Still looking for new ways to effectively process the waste Li batteries, so for example bio-metallurgy is also used. The Li-Ion batteries also contain other metals such as cobalt, copper, nickel and aluminium outside of lithium, which are very difficult to obtain. There are many types of lithium batteries, and the content of these metals is variable in each battery components. This paper is focused on the recovery of these metals by a pyrometallurgical process using a collector.

Microstructural analysis and micro-hardness measurement of experimental repair weld joints were important parts of the development of a method for repair welding a VVER 1000 pressure vessel. Filler metal (Inconel 52M) was deposited on the materials used for the production of the pressure vessel: the base material of 15CHMNFA steel, the weld metal of the circumferential weld joint and the austenitic cladding of the inner surface of the pressure vessel. The investigation using light, scanning and transmission electron microscopy was concentrated on the heat affected zones (HAZ) beneath the repair weld of Inconel 52 and on the weld metal.
The aim of this contribution is a comparison of results obtained by “standard” scanning and transmission electron microscopy (SEM, TEM) and “advanced” EM method using a solid-state Concentric BackScatter detector (CBS), which enables effective energy and angular separation of the back-scattered electrons. This new method allows gaining better information about microstructure compared standard SEM and partially replacing TEM observation.

In the present work, the computer simulation of hysteresis loops of (Nd1-xPrx)2Fe14B compounds with different Pr contents was performed for a temperature range of 300-5 K. The simulation results suggest that the alloying of Nd2Fe14B with Pr (1) leads to reducing the negative effect of the spin-reorientation phase transition on the residual magnetization of the compound (Nd1-xPrx)2Fe14B, (2) reduces the slope of the demagnetization curve making the hysteresis loop more rectangular, (3) does not have a noticeable effect on the maximum value of the coercive force, shifting its maximum to lower temperatures as the Pr content increases. Thus, the alloying of Nd2Fe14B-based compositions with Pr can increase the temperature stability of the hysteresis characteristics of permanent magnets and ensures their operation at low temperatures without loss of magnetic properties.

In the scope of this paper, the usage of the miniature samples and investigating using small samples is discussed. The miniature samples were used for determination of mechanical properties for titanium alloy deposited by additive manufacturing. The tensile tests on the standard and the miniature samples were provided for commonly used Ti-6-Al-4V alloy. These titanium alloy samples were produced by electron beam melting and by selective laser melting method that belongs to powder bed fusion processes of 3D printing. The purpose of this work was to demonstrate that local material characteristic can be obtain using the miniature specimen. The usage of small samples could provide many advantages for testing of mechanical properties. In our investigation it is shown that the results are in good agreement for standard and miniature specimens. The strength characteristics reached identical values. However, the plastic characteristic, such as elongation and reduction of area, are not comparable duo to the presence of internal defects. The small defects, such as lack of fusion or pores, have major impact on the miniature samples in comparison to the negligible influence on the larger specimens. The fractography included in this research reveals the differences for the small and standard size specimens.

Nanostructured (Ti, Cr)C (Ti, W)C solid solutions powders were successfully synthesized by mechanical alloying (MA) from the mixture of titanium, chromium and graphite (carbide 1), and titanium, tungsten and graphite (carbide 2) under argon atmosphere. MA was carried out in a high energy planetary ball mill Fritsch Pulverisette 7, at room temperature. Microstructure changes, such as crystallite size, microstrains were determined from the Rietveld refinement of the X-ray diffraction patterns. Scanning electron microscopy (SEM) was employed to examine the morphology of the samples as a function of milling times. Transmission electron microscopy (TEM) was used to measure nanoparticles size of the samples. However, the morphological and microstructural investigations indicate that Ti, W and Cr were homogeneously distributed in the solid solution powders. X-ray diffraction results show the nano-scale single-phase solid solution could be prepared with a short time of milling. In addition, the obtained solid solution powders were also used in the preparation of (Ti, M)(C, N)-based cermets to show its high potential in future application as cutting tools.

Successive development of new difficult-to-machine materials requires the adaptation of new efficient methods of their treatment, especially in finishing machining stage, which are of great importance in manufacturing processes. One of the most common finishing treatments is grinding. In order to increase the efficiency of the grinding process and improve the quality of the surface finish, it began to produce grinding wheels with varied granulation. The following article presents the results of a reconnaissance research of the grinding process in which multi-granular grinding wheels made of green silicon carbide were used. The purpose of the experimental research was to investigate the influence of input parameters on surface roughness parameters. The workpiece material used in the present investigation was Inconel 718. The study was carried out with an experimental methodology design. Input parameters were: cutting speed Vc, cross feed rate Fp, longitudinal feed rate Fw. In order to characterize the surface texture after grinding process, surface roughness St and Sz parameters were described. Using the obtained results, statistical models of the grinding process were developed, which will enable selection of the most favorable processing parameters depending on the quality of the surface finish.

Annealing of structure defects in Ti alloys bends out of shape the type of internal friction (IF) Q-1(Т) temperature spectrum. The possibility to trace on the same specimen dependence elastic module E on different continuously changing factors of temperature or irradiation. The relaxation IF maximum at ТМ ≈ 400 К, conditioned by the process of reorientation of interstitial hydrogen atoms in dumbbell configurations H-H. Temperature dependence of IF Q-1(T) and elastic module E(T) (directional surface of inelastic-elastic body) and 2D, 3D AFM microstructure of VT3 Ti alloy after mechanical and thermal treatment is represented The quasilongitudinal ultrasonic (US) velocity V║ = 504 m/sec, elastic module E = ρV║2 = 15.24 МPa, “fast” quasitransversal US velocity V┴1 = 280 m/sec, shear module G = ρV┴12 = 4.704 MPa, Puasson coefficient μ = 0.3532, specific density ρ = 60 kg/m3 of porous polystyrene are determined from the oscillograms.
The Puasson coefficient μ is equal to ratio of relative transversal ε┴ compression to relative longitudinal lengthening ε‖. Debye temperature θD, Puasson coefficient μ were determined.
Thus, the measuring of internal friction background Q-10 after mechanical treatments gives information about the changes of the fields of elastic strains σi in Ti alloys.

The alloys based on intermetallic phases involving aluminum belong to group of heat resistant materials. Their physic-chemical and mechanical properties allow to apply them in the operating conditions in corrosive environment and elevated temperature. Research conducted for many years has shown that these materials can work in temperature to 1100 °C. The paper presents the morphology of oxides formed during oxidation Fe40Al5Cr0.2TiB alloy in 700 °C during 300, 1000 and 2000 h in the air and water vapor environment. In addition, the material was after casting and after plastic processing. The study allows to define the surface condition and morphology of corrosion products carried out using scanning electron microscopy together with EDS X-ray microanalysis.

The focus of present research is on the behaviour of rare earth metals as dopants in zinc oxide rich borophosphate glasses. Attention is turned on the influence of Sm, Eu, Gd and Nd on the structure and optical properties of these new materials. Analysed glasses 71.81 ZnO - 18 B2O3 - 9.69 P2O5 - 0.5 RE2O3 (mol%) were prepared by conventional melting quenching method. The ratio of the main components - ZnO, B2O3, P2O5; the content of the dopant rare earth element (Sm, Eu, Gd, Nd) and the conditions of synthesis and analysis are set on the basis of literature data and our previous studies. The structure of the synthesized samples was investigated by powder X-ray diffraction, differential scanning calorimetry and infrared spectroscopy, and their optical properties - by photoluminescence analysis. The synthesized rare earth doped glasses are mainly amorphous with the presence of one or more crystalline phases in some of them - SmPO4, GdPO4 and NdPO4. They have the typical structure of borophosphate glasses - the presence of PO4 tetrahedra and BO4 tetrahedra. The high glass transition temperature of the synthesized materials (above 500 °C) is an indication of the stability of the glasses obtained. The RE-doped ZnO-rich borophosphate glasses have a potential for practical application in optical devices for engineering, electronics and medicine.

High pressure die casting technology is one of the most productive technologies for producing thin-walled aluminum parts in mass production. Along with high productivity, it offers high precision, very good surface quality, fine-grained texture without tightenings with good mechanical properties. One of the ways to increase the economic efficiency of the high pressure die casts production while adhering to the prescribed quality properties represented by the mechanical properties of casts, is using the remelted material in high pressure foundries. This contribution is conceived as a cross-sectional study of the remelted material implementation in the high pressure die casting technology. The study is focused on the technological and economic aspects of the remelted material implementation into the production of aluminum based high pressure die casts. The results of the operational experiments show that the proportion of the remelted material in the batch increases the porosity of casts, reduces the mechanical properties of casts and adversely affects the chemical composition of the input alloy. The proper ratio of pure and remelted material in the melt, while maintaining the prescribed quality requirements for cast, entails significant economic savings. The presented contribution serves as a summary of knowledge in the field of metallurgical preparation of aluminum alloys and implementation of remelted material into production.

The microstructural and phase evolution of the powders at different times of milling and after treatment in the flow of the thermal plasma were studied. The X-Ray Diffraction and Scanning Electron Microscopy studies showed that increasing milling time up to 12 h improves chemical homogeneity of the powders and promotes the formation of B2/β-phase solid solution, while at shorter milling times the powders consist of a highly inhomogeneous layered structure with HPC- and BCC-crystal structures. The plasma spheroidization of irregular powders after MA resulted in highly-spherical powders of the orthorhombic alloy with a homogeneous chemical composition consisting of dendritic B2-phase. The fabricated spherical powders can be utilized in Additive Manufacturing processes to fabricate intermetallic components.

In recent years, the application of various additions (hydrides, oxides, intermetallic compounds, etc.) to powder mixtures for manufacturing Nd-Fe-B magnets shows promise as the method that allows one to increase the hysteretic characteristics of the magnets at the expense of realized grain-boundary diffusion and grain-boundary structuring processes. The hysteretic characteristics of sintered Nd-Fe-B magnets are highly sensitive to their microstructure and composition of phases. This paper is focused on the coercivity enhancement of the near-stoichiometric Nd2Fe14B-based magnet by optimizing microstructure, which included processes of grain boundary diffusion and grain boundary structuring via the application of hydrogenated Dy3Co0.6Cu0.4Hx compound added to the powder mixture. The base alloy having the composition Nd-24.0, Pr-6.5, Dy-0.5, B-1.0, Al-0.2, Fe-balance was prepared by strip-casting technique and subjected to hydrogen decrepitation during heating to 270 °C in a hydrogen flow at a pressure of 0.1 MPa and subsequent 1 h holding at this temperature. Dy3Co0.6Cu0.4 alloy was prepared by arc melting in an argon atmosphere and subjected to homogenizing annealing at 600 °C for 90 h. The subsequent hydrogenation under the conditions used for the decrepitation of the strip-cast alloy. The phase composition of Dy3Co0.6Cu0.4 was studied by X-ray diffraction analysis, DTA and scanning electron microscopy, electron microprobe analysis. Additions of the hydrogenated compound to Nd-Fe-B-based sintered magnets allow us to manufacture magnets with Br = 1.34 T and jHc = 1120 kA/m. The microstructure, phase composition and distributions of REM, Co, Cu for the prepared magnets were investigated by SEM/EDX method. Stability of structure-sensitive parameter, namely, the coercive force jHc of the sintered magnet prepared with 2 wt% of Dy3Co0.6Cu0.4Hx addition was studied.

Recent advances in fast scanning calorimetry (FSC) allow investigations upon a much wider range of systems, now including many industrially relevant metallic substances, e.g. Ag, Al, Mg, Zn, Sn and Pb based alloys, and therefore necessitate the development and improvement of measurement strategies for metallic systems in general. The work here explores specific heat capacity (cp) measurements via FSC, with a focus on correcting the measured heat flow by accounting for temperature dependent heat losses. Using MultiSTAR-UFS1 sensors with the Mettler-Toledo Flash-DSC 2+, the cp of Pb (99.998 % purity) was measured in dependence of the sample mass and scanning rate. Masses from 0.3 to 5 µg are evaluated at rates of 100, 1000 and 2000 K s-1 in the temperature range -20 to 320 °C. Two loss-correction methods are shown and compared to cp results without corrections. Heat loss corrections are mandatory when measuring cp, but are in particular important for low masses and rates. High consistency is found between the two proposed correction procedures, giving good confidence in their viability. A slight but consistent overestimation of cp compared to literature casts some uncertainty upon the determined sample mass. Whilst the systems under study in this work encompass only pure Pb, the arguments and procedures of the shown method of cp determination are applicable to any system in the absence of physical transformations.

The results of research on diamond segments made on metallic binders and on synthetic - resin binders for granite surface grinding are presented. The results of investigations of hardness of abrasive segments were determined by the Brinell method for metallic and Shore segments (D) for segments on synthetic binders. The hardness of the segments affects the ability to hold the diamond grain in the binder, which is related to the wear of the abrasive segments during their work. Tribological tests of their wear during operation (in given research cycles) for which the weight losses of abrasive segments in the process of grinding the granite surface with hardness of 7 Mohs, with constant kinematic parameters and constant pressure were determined. The results of microscopic analysis of working surfaces of the tested segments were presented in order to determine the ability to hold diamond grain in a segment matrix, using a Nikon Eclipse MA200 microscope.

The sulphide phase of ore minerals is subject to passivation in oxidizing conditions. The kinetics of dissolution of polycrystalline sulfide minerals - the raw material of hydrometallurgy of molybdenum, copper, under conditions of variable hydrodynamics of interaction with the medium, is adequately described by the method of a rotating disk of dissolved material with a surface equally accessible to the diffusion of reagents. Overcoming the passivation of their surface is described by kinetic equations based on model representations. Objective: on the example of the behavior of Mo-concentrate in nitrate and hypochlorite electrolytes to describe the nature of the resulting products and the kinetics of their dissolution. Samples of Mo-concentrate (38 % Mo in MoS2 phase) were used. The concentration of Cu (II), Fe (III), Mo (VI), Re (VII) ions in solutions was determined photocolorimetrically and spectrometrically (AAS Perkin-Elmer 3030B, ICP- Aligent 7500 ICP MS); thermal analysis was carried out by dilatography, and microscopy of samples was carried out on scanning electron microscopes: SEM-EDS EVO-MA (Carl Zeiss Instrum) and JCM - 6000 Neoscope II (JEOL); spectral analysis - on a Nicolet iS50 FT-IR spectrophotometer (Thermo Scientific, USA), diffuse reflection electronic spectra - on a UV-2600 spectrophotometer (Shimadzu); structural and phase analysis - on an XRD Empyrean X-ray diffractometer (PANalytical), kinetic measurements were performed on powder samples of sulfide concentrates, t:W = 1:7 and 1:75. For example, oxidation of Mo-concentrate samples in a sulfate-hypochlorite electrolyte, during 1800 seconds, the destruction of the phase of Mo, Cu sulfide compounds was established, with the transformation of their share into the oxide-sulfate phase. The kinetics of oxidation of a number of minerals in a sulfate-hypochlorite electrolyte was studied in the temperature range 20-40-70 °C, at atmospheric pressure. The samples of the solid phase after their leaching were studied by the methods of thermal analysis, optical, UV and IR spectroscopy, X-ray diffraction, electron microscopy, and probe microanalysis of the surface areas of the grains.

Nowadays the technological progress of the railway transport is characterized by high demand for new material and technological solutions throughout the whole construction whilst taking into account the carrying and conducting traction equipment, which is traditionally manufactured from pure materials via continuous casting and die forging. The current renewal works of the railway trunks carried out all over Europe connected with simultaneous expansion generate large amounts of traction scrap in the form of worn-out carrying ropes and overhead contact lines. Therefore, research work was undertaken in order to develop new recycling technology of the aforementioned scrap into new traction equipment. The first works related to the development of this technology which assumes the use of minimum 80 % of the traction scrap was directed into identifying the occurring impurities on the surface of the tested materials and their direct influence on the final properties of the product. Firstly, the analysis of the thickness of the impurities layer on the surface of carrying ropes and overhead contact lines and the chemical composition analysis with the use of the scanning electron microscope was conducted. The majority of the impurities were oxygen and silicon. In order to investigate the influence of these impurities on the new material obtained from the traction scrap the tested materials were melted and crystallized. A large number of impurities in the copper matrix were detected and they may have a direct impact on the production processes (die forging, supersaturation, artificial aging) of the new carrying and conducting traction equipment.

The TIG welding process is well known for its advantages and exclusivity when it comes to weld materials such as Titanium, Magnesium, Aluminium, etc. which requires special conditions, therefore in this experiment we use TIG welding procedure to join two materials to two different base materials: Cu-(FM) on ferritic stainless steel-(BM); Mg-(FM) on Copper-(BM). In this paper are analysed intermetallic compounds and constituents formed in different zones of welded sample: HAZ of base material, fusion line, fusion zone, etc. To produce qualitative, braze-welded joints between dissimilar materials, we need to fully understand and take in consideration different factors. Obtained results are evaluated by optical microscopy, scanning electron microscopy and EDX-analyses.

The paper deals with an experience with innovation process of a technical solution of apparatus for processing metals of loose nature tending to air oxidation, especially alkaline earth metals. The aim of this technical solution is to design a device facilitating the process of treating rare earth metals in a way that would prevent their air oxidation and thus facilitate their handling in the next technological process. The utility model called “apparatus for processing metals of loose nature tending to air oxidation, especially alkaline earth metals” has been created of a standard device to prevent air oxidation without the use of protective devices and thus to facilitate their further handling.

This article presents studies of the of lightweight mesh structures properties made by selective laser melting technology. The study of lattice structures with different sizes of struts was made. Also, methods for optimizing grid structures with variable strut sizes were also used. The structure of the mesh elements after hot isostatic pressing and heat treatment was studied. The results of changes in porosity and mechanical properties of lattice structures after hot isostatic pressing and heat treatment as compared with properties of cortical bone are shown. The presented results can be used in the manufacture of medical implants in order to reduce their weight, improve implantation, while ensuring optimal mechanical properties.

Ni-45Ti-5Zr (at%) alloy was prepared by two different methods - by plasma and vacuum induction melting. Two samples were cut out both the ingots - the first out the edge and the second out the centre of the ingots. The aim was to confirm homogeneity of the ingots. Metalographical sections were used for photodocumenting of a microstructure, for verifying of chemical composition with EDS analysis and for statistic description of phases. Moreover, both the ingots were used for determination of C and O contents. In the both cases, structure was polycrystaline with a significant Zr segregation along dendrite boundaries. Chemical composition for the centre and the edge of the ingots was different only for the ingot prepared by plasma metallurgy. Unfortunately, both the ingots were contaminated with higher C and O contents.

The main issue occurring during the process of point resistance welding of sheets with anti-corrosion coating in the form of zinc layer is the phenomenon of diffusion of zinc to the welding caps manufactured from copper alloys. As a result of the current flow the temperatures in the core of the weld may reach over 1500°C and within the point of contact between the sheet and the welding cap even up to 1000°C which causes the zinc layer to melt or even to evaporate. The ongoing diffusion of zinc to the welding caps causes the decrease in its mechanical and electrical properties which speeds up their wear and tear. Due to the complex mathematical models defining the degree of diffusion in the multi-component materials of different structure, an experimental method was developed to asses the galvanizing degree of copper alloys. Such method covers the conditions occurring during the resistance welding process, i.e. exposure to high temperature and the environment of liquid zinc. Initial preparation of test samples includes the surface preparation by pickling in the H_2 SO_4 acid and the use of the ZnCl_2/NH_4 Cl flux with the proportions of 1:3. The initially prepared samples were immersed in the liquid zinc for 1 minute. The verification of the penetration depth of zinc into the materials was carried out using a scanning electron microscope, determining the chemical composition by the EDS method.
Authors are grateful for the financial support provided by The National Centre for Research and Development - Research Project No. TECHMATSTRATEG1/347960/6/NCBR/2017.

The use of aluminum alloys in many industrial sectors is still increasing today. Due to its excellent properties, aluminum is widely used, for example, in construction, food, and automotive industries. The increase in the use of aluminum is also accompanied by increasing demands for chemical and metallographic cleanliness of this metal. The presence of unwanted phases in the molten metal can cause changes in final castings properties, such as porosity, corrosion susceptibility, electrical and thermal conductivity, etc. These phases are represented especially by harmful gases and non-metallic inclusions. Although significant progress has been made in the field of metallurgy in recent decades, great attention is still being paid to the optimization of metallurgical processes. Refining technology of aluminum melts is not the exception. Reducing refining time and process intensification often results in significant financial savings. This work is focused on the actual phase of research and development of refining technology of aluminum melt by an inert gas, through numerical modelling in ANSYS Fluent simulation software.

Metallography is the study of the microstructure of all types of metallic alloys. By extension, the same principles can be applied to the characterization of any material. Metallographic analysis of a materials microstructure helps us first of all in identifying of composition and thermomechanical history of a material determining if the material has been processed correctly and is therefore a critical step for determining product reliability and for determining why a material failed. Nowadays many non-commercial computer-aided programmes are being developed and applied to metallographic investigations. The paper presents selected examples of application of two non-commercial programmes to metallographic investigations of γ’ phase precipitates in Ni-based superalloy CMSX-4. The aim of the research is to demonstrate some possibilities of the programmes and to discuss some aspects of image selection for the research, image preprocessing, and morphological and mathematical transformations, which can effect quantitative results of metallographic analysis.

The shape memory effects and superelastic behavior of Ni-rich NiTi alloys (> 50.6 at% Ni) are significantly dependent on microstructural changes during heat treatment. Furthermore, it is also generally known that thermal treatment of Ni-rich NiTi alloys induces diffusion processes that lead to precipitation. Depending on temperature and holding time, several types of precipitates can be formed in microstructure of the alloy. Assumed transition path is: metastable Ni4Ti3 - metastable Ni3Ti2 - stable Ni3Ti. Thus, these and other microstructural changes can have a major impact on the martensitic transformation in NiTi alloys and, essentially, on the transformation temperatures. In addition, the precipitation of secondary phases can also contribute to a substantial increase in the strength of NiTi alloys. Another critical factor affecting the properties of these materials is the composition. The experimental samples of NiTi alloy with 50.7 at% Ni were subjected to heat treatment. The thermal regimes consisted of aging treatment at 300, 350 and 400 °C for 0.5 h followed by air cooling. The microstructures before and after the heat treatment were observed by optical microscopy. The study was completed by microhardness measurement and X-ray analysis. The obtained results show that the aging temperatures led to microstructural and microhardness changes for the investigated alloy.

Using the methods of scanning electron microscopy, X-ray microscopy, XRD analysis, differential scanning calorimetry and hysteresis properties analysis, complex studies of the powders with a nominal composition of 90% [43% Fe2O3 - 57% FeO] - 10% Gd2O3 in the states after high-energy milling for 15 hours and after heat treatment for 30 minutes in the temperature range of 200 ... 900 °C have been carried out. It has been established that after high-energy milling, the main phase components of the powders are magnetite (Fe3O4) and the amorphous phase. In addition, there are about 2 vol. % wustite (FeO) and less than 1 vol. % orthoferrite (GdFeO3). The joint analysis of the results of phase-structural studies and hysteresis properties analysis of the powders in the initial, after high-energy milling state and after heat treatment allows us to conclude that Gd3+ ions dissolve in the Fe3O4 lattice, replacing Fe3+ in the reverse spinel octahedral positions. The maximum experimentally obtained value of the Gd content in powders is approximately 5.1 at.%. It means that there is the fundamental possibility of the existence and production of magnetite doped with Gd. Which can become a promising double T2-T1 contrast agent for MRI, if an effective chemical method for its synthesis in a nanosized state is developed.

In this study, we investigated the effect of aluminum content and precipitation on the corrosion behavior of the AZ31 and AZ80 magnesium alloys. The investigated alloys were received in the as-extruded condition in order to retain comparable grain size and texture. First, solid solution treatment was performed on the samples of both alloys. Subsequently, the samples were isothermally aged at 200 °C for 20 hours. The scanning electron microscopy was used to study the grain size and microstructure. The corrosion properties of samples were studied by potentiodynamic polarization measurements and the AE signal was concurrently recorded. Solution treated AZ80 and AZ31 samples exhibited similar behavior. The aged AZ80 sample showed lower corrosion rate. Also, a strong breakdown appeared in the later (compared to other samples) stage of the potentiodynamic test. The breakdown was found to be easily recognized by AE parameters.

High demand in metals coupled with the depletion of metal reserves, slag has become a second source. The demand in copper remaining high while Copper mines are being lesser are lesser, any treatable copper source are targeted. The current investigation focuses on the impact of ferro-silicon and gypsum collected from hydrometallurgical plants both to favour the formation of matte and. Carbon monoxide was blown in at 0.04 l/min for reduction. The head samples and products were characterized using XRF, XRD and SEM. The copper slag, ferrosilicon and gypsum were crushed and milled together for 15 min to obtain a homogeneous head sample. An alumina tube furnace set at 1400 °C was used for the experiment. Based on previous work, the basicity was kept at 0.7 through gypsum addition. The sample was kept for two hours in the furnace at the set temperature and the furnace was switched-off to cool down slowly. A graphite crucible was used. The little matte observed in the head sample entrapped from previous matte production. However, the final produced slag showed more matted formed collecting more copper with high iron content, thus low copper grade due to ferrosilicon addition. Although the distinction between the new matte and new slag was a challenge due to the matte layer very thin, the recovery of copper from the slag was successful. The correlation between the amount of ferrosilicon and the matte grade was found to be inverse proportional due to the amount of iron added through ferrosilicon. Also, the role played by gypsum both on the formation of copper matte and as a flux was very effective in copper coupled with good slag-matte immiscibility. The characterized raw Cu slag showed trace of Ge in the SEM-EDS results and a fayalitic slag containing some little matte.

As primary resources become more and more complex in their chemical composition and some places poor in their valuable metals in the ore secondary sources like slag phases from the production processes get in the focus of the metal industry. Currently about 70 % of copper slag remains is ineffectively utilized. Hence the need of their treatment and attend to ecological environment problems that they might cause. The current study focuses on the recovery of copper from copper slag by using gypsum formed during impurities removal in hydrometallurgical plants. The fayalitic slag was provided by Gecamines in the DR Congo and the gypsum from the small scale hydrometallurgical plant in Lubumbashi in the Democratic Republic of Congo. The gypsum played a double role of sulphur provider and flux. The aimed basicity of the slag through the addition of gypsum was 1. XRF, XRD were used to characterize gypsum whereas the slag and the subsequent products analysed with XRD, XRF and SEM. The working temperature was set at 1400 °C for two hours with CO blown at 0.2 l/min in the furnace to allow copper to be freed from other oxides and form a sulfide. Graphite crucible was used in an alumina tube furnace. Coke was added to limit crucible reaction. The heating rate was 7 °C/ min. Results confirmed the presence of covellite and FeS stating matte effectively formed while anorthite was present in the slag confirming the influence of the CaO added through gypsum on the final slag produced.

The paper describes the use of physical modelling to study the degassing of aluminum melts in the refining ladle by inert gas blowing. The technology of blowing inert gas into the ladle through a rotating impeller is the most common method in operating conditions to reduce the unwanted phases content in molten aluminum, e.g. hydrogen. The high efficiency of this process is related to the creation of fine bubbles with a high interphase surface, their equal distribution into the whole volume of the refining ladle and with relatively long period of its effect in the melt. The presented paper is focused on the evaluation of laboratory experiments obtained using the physical modelling method; special attention is focused on the assessment of relevant parameters for the degassing process - flow rate of inert gas, rotary impeller speeds and impeller variant.

Aluminum is the leading metal in non-ferrous metallurgy with an annual production of 74.9 million tonnes in 2017. About 16.25 million tonnes were produced in secondary metallurgy. The importance of recycling has greatly increased in recent years, largely due to the better availability of secondary materials and to the economic and environmental benefits of secondary metallurgy. Scrap pre-treatment is of great importance as part of the aluminum recycling process. As such, the effects on the formation of dross as well as on the metal yield are of interest. In this work the melting behaviour of aluminum profiles is investigated, in some cases where previous pyrolysis has taken place. Therefore, four melting experiments are carried out with starting materials that differ in the proportion of paints, plastics and pyrolysis residues. The melting process of the feedstock is performed by addition to a liquid primary aluminum melt. This is obligatory for the simulation of the industrial melting process in a two-chamber furnace. The determination of the amount of dross and the different metal yields are of significant interest. Generally, the amount of dross formed increases with increasing content of impurities and the metal yield decreases. In conclusion, the mass of formed dross as a function of the organics or pyrolysis residues is shown graphically.

In today’s world the issue of energy storage is getting more and more attention and novel battery design are proposed for specific purposes. Lithium batteries are a promising high-energy-density power source and many new concepts are being explored. In this work we propose the alloys from the Ga-In-Li system as a potential material for anodes in liquid batteries. Due to the fact that there is no literature data available on the thermodynamic properties in this ternary system we measured the electromotive forces of chosen compositions and determined the basic thermodynamic properties in this system. Moreover we aimed at characterizing the phases equilibria and phases transformation in the above-mentioned system. EMF measurement was conducted in a cell, where the potential difference between anode and cathode of the material is recorded and plotted against temperature. Eutectic LiF-LiCl salts are used to electrolyte preparation and the cells were prepared in a protective argon atmosphere. The obtained experimental results will be important in the case of the design of a suitable electrode material in future liquid batteries.
ACKNOWLEDGEMENTS: The research was co-financed by the European Union from the resources of the European Social Fund (Project No.WND-POWR.03.02.00-00-I043/16).

The objective of this work is to investigate the effect of surface orientation on corrosion performance of a nickel-based alloy IN 738. Three planes with different orientations were prepared by cutting at given angles of single crystal specimen. The electrochemical polarization behavior of three crystallographic planes was studied using different techniques. Potentiodyanmica polarization and electrochemical impedance spectroscopy (EIS) measurements show that corrosion behavior of the specimen varies with crystallographic orientation. Along certain orientation, an increase in the concentration of corrosive solution causes significant change in corrosion resistance, while along other orientations, the alloy shows smaller and negligible change in corrosion resistance with concentration. This behavior causes the orientation dependence of corrosion behavior of the alloy to become more pronounced as the concentration reduces. Potentiostatic polarization test and X-ray photoelectron spectroscopy (XPS) analysis demonstrate that the protective passive films formed on three crystallographic planes are different in both chemical compositions and compact properties, resulting in anisotropy of corrosion behavior.

The article deals with machining and development of the wear of cutting tools for turning of nickel alloy Inconel 718 - 2.4648. This alloy is characterized by high strength and toughness, low thermal conductivity and high abrasion. As a result of these properties, the alloy has worsened machinability and it is necessary to put emphasis on technology, a choice of cutting tools, their geometry and cutting conditions. The exchangeable cutting inserts marked VBMT 160402F-1, made from sintered carbide and pre-verified cutting conditions were used for machining of the alloy. The microgeometry of cutting tools was defined with brushing technology and abrasive jet machining technology. The edge radius rn = 20±5 μm on cutting inserts was created by the brusher with abrasive corundum particles and the edge radius rn = 20±5 and 35±5 μm was created by abrasive jet machining technology. A gradual wear development and its intensity was checked during turning process of Inconel 718 with the use cutting tools with rectified cutting edge. Depending on intensity of a wear on major flank was determined a tool-life of cutting inserts and an influence of the microgeometry on machining process of alloy was considered.