Seznam abstraktů 2025: POSTEROVÁ SEKCE E

Bioceramics has long been known for its positive interactions with the human body, and for this reason it is eagerly used in medicine, surgery, dentistry and tissue engineering. Due to their exceptional biocompatibility, osteoconductivity and osteoinductivity, bioceramics are currently used more often than autologous, allogeneic or xenogeneic grafts in the repair of bone defects and the regeneration of bone tissue. This review focuses on ceramic, glass and glass-ceramic materials used in bone tissue engineering, mainly in the form of porous scaffolds. These materials should resist stress and stimulate the healing process by actively participating in tissue growth and regeneration, facilitating cell migration and the flow of nutrients. and metabolites. The mentioned groups of ceramic biomaterials, their properties and applications, as well as the latest trends aimed at improving them in terms of their most sensitive properties, such as mechanical strength and septic properties, will be discussed here.

Body implants, including hip implants, continue to present significant challenges for the scientific community. The most commonly used alloy for hip implants, Ti-6Al-4V, has several limitation such as high toxicity, as vanadium (V) is considered a toxic element, or its relatively high elastic modulus ( ̴ 100 GPa) compared to that of cortical bone ( ̴ 20-30 GPa).
Approximately two decades ago, a new class of titanium alloys, known as metastable β-titanium alloys, was developed. These alloys contain only non-toxic elements. They can achieve significantly lower elastic moduli, as low as 50 GPa, however, their strength remains limited. Conversely, when these alloys possess high strength, their elastic modulus often becomes unsuitable for implant applications.
Taking these factors into account and considering the potential for varying material properties along the length of the hip implant, it becomes evident that a more optimized approach could be beneficial. Specifically, the distal portion of the femoral stem, which interfaces with the bone, should exhibit lower stiffness (a lower elastic modulus), while the proximal portion (the neck of the stem) should be designed to be stiffer and as strong as possible. To achieve this, the development of a functionally graded material (FGM) through additive manufacturing (AM) techniques would be advantageous. Titanium alloys are particularly suited for this purpose, as their mechanical properties can be tailored with small changes in chemical composition. Additionally, methods of AM have their advantages in producing near-net shape materials with controlled gradients in chemical composition.
This study investigates a potential implant material: Ti-Nb-Fe-Sn alloy system fabricated via selective laser melting (SLM). To identify the optimal strength-elastic modulus combination for each section of the hip implant, 10 different chemical compositions were examined, each processed under varying deposition power and speed parameters during SLM. The resulting materials were thoroughly analyzed using a broad range of experimental techniques. This allowed us to select the best chemical compositions and processing conditions for achieving one alloy with a low elastic modulus and another with exceptional mechanical properties, particularly high strength.

Titanium alloys may serve as hip implants due to their biocompatibility and matching mechanical properties. The requirements of the performance on the different parts of an implant may differ - e.g. in a hip implant, high strength σ is desired for the proximal side, whereas low modulus of elasticity E is anticipated for the distal side. Such contradictory demands may be satisfied by employing graded materials with different mechanical properties fabricated by additive manufacturing. In our work, ten different Ti-based alloys with varying content of Nb, Fe and Sn were fabricated by selective laser melting. A set of five chemical compositions was combined into a single sample with a graded composition. The microstructure of the as-deposited materials was studied by the means of scanning electron microscopy and the mechanical properties were assessed by measurement of Vickers microhardness and resonant ultrasound spectroscopy. Three different laser powers and three printing speeds enabled production of materials with different microstructures. High speed and low power resulted in inhomogeneous grain structure with undissolved particles. Decreasing the speed gave rise to homogeneous structure with fine grains. Increase in the power led to elongation and coarsening of the grains. The microhardness and elastic properties were influenced mainly by the composition of the alloys - Fe caused increase of the HV, where as addition of Nb and Sn on the expense of Ti resulted in HV decrease.

The paper presents the results of microstructure and crystal perfection analysis performed for single-crystal (SX) turbine blades used in aircraft engine high-pressure section. CMSX-4 nickel-based superalloy turbine blades were manufactured in the Bridgman-Stockbarger process with the withdrawal rate varying between 5 and 7 mm/min. The heat treatment of single crystals consisted of solution annealing and double aging. Microstructure analyses of single crystals were performed using light, scanning and transmission electron microscopy. The full crystal orientation of the blade castings was also determined. Primary orientation α angle, which is the value between the [001] crystallographic direction and the axis of the blade, β angle, defined as the rotation of the [001] direction around the direction of casting withdrawal rate from the furnace, and γ angle - the deviation of the projection line of the [010] direction vector from the adopted reference axis, were defined. Measurements of the angle values characterizing the crystal orientation of the blades were made using the Ω-scan method and OD-EFG1 X-ray diffractometer. In addition to structural analysis, creep tests were performed in order to verify the assessment of the perfection of the crystal structure of SX blade castings. The obtained test results of the creep test showed a difference in the mechanical properties of the CMSX-4 superalloy for variable conditions of the Bridgman-Stockbarger process.

This study investigates the damping capacities of Ni48-xMn46Sn6Cux (x = 5, 7.5, 10, 12.5, 15) shape memory alloys (SMAs). X-ray diffraction (XRD) and differential scanning calorimetry (DSC) analyses show that all Ni48-xMn46Sn6Cux alloys are in the martensitic phase at room temperature, with the martensitic transformation temperature and transformation enthalpy (ΔH) decreasing as Cu content increases. Scanning electron microscopy (SEM) observations indicate that grain size is not significantly correlated with Cu content. Hardness tests show no significant effect of Cu addition on alloy hardness. Dynamic mechanical analysis (DMA) results indicate that with increasing Cu content, the damping capacities of the inherent and intrinsic internal frictions (IFPT+IFI) peak first increase and then decrease. Among these alloys, Ni40.5Mn46Sn6Cu7.5 was the most suitable for high-damping applications. Compared to other SMAs, the Ni48-xMn46Sn6Cux SMAs exhibit not only high damping capacities at a temperature above 100°C, but also advantages such as low cost and simple control of the desired martensitic-transformation temperature by adjusting the chemical composition of the alloy.

High-entropy alloys (HEAs) are a relatively new group of metallic materials. The idea behind the chemical composition of these materials is the content of five or more alloying elements of similar atomic concentration. This usually ranges from 5 to 35%. High-entropy alloys exhibit unique physical and chemical properties and show promising prospects for their industrial application in the near future. These applications could include the manufacture of whole components or layers of high-entropy alloy using modern deposition methods such as laser metal deposition, thermal spraying and PVD (Physical Vapour Deposition). These deposition methods require either a wire or powder material for the layers, or in case of PVD, the bulk sputtering target. The most common spherical powders used for laser metal deposition, thermal and plasma spraying are produced by gas atomization with induction melting of the material feedstock. In this work, a new ultrasonic atomization method has been used to produce a high-entropy alloy powder of 0.7AlCoCrNiFe0.2Ti. The powder atomization and examination of the produced material has been the objective of this research. The tests included light microscopy, electron microscopy, particle size measurements, and X-ray diffraction studies. The results showed that the powder has a desired spherical morphology, with a particle size in the range of 7-50 μm. The microstructure of the powder is dendritic. X-ray diffraction (XRD) also showed that the powder is consisting primarily of a solid solution with a BCC structure.

This study investigates advanced composite materials consisting of a NiAl matrix reinforced with an FeSi phase, which are considered promising candidates for next-generation tool applications, with the potential to replace conventional high-speed steels alloyed with tungsten and cobalt. The alloys were synthesized via vacuum induction melting followed by centrifugal casting. To further tailor their microstructure, an experimental alloy with a 1:1 mass ratio of matrix to reinforcing phase was subjected to directional solidification using the Bridgman method. The process was carried out at a temperature of 1450 °C with a holding time of 30 minutes, followed by controlled crystallization at a rate of 100 mm/h. Microstructural characterization was performed using the light optical microscopy (LOM) and scanning electron microscopy (SEM). The chemical composition was determined by energy-dispersive X-ray spectroscopy (EDX), and the microhardness was measured using the Vickers indentation method. In the as-cast state, the alloy exhibited a typical in-situ composite microstructure consisting of primary NiAl-based dendrites and interdendritic regions containing lamellar eutectic structures and discrete reinforcing phases. The eutectic structures were composed of alternating FeSi- and NiAl-based phases, while certain interdendritic areas were occupied by an FeSi-based phase with only minor Ni and Al content. Directional solidification via the Bridgman method, which enables controlled solidification through precise regulation of the temperature gradient and solidification front velocity, significantly influenced the morphology and distribution of these phases. As a result, the alloy featured a more refined, oriented, and homogeneous microstructure, which is beneficial for improving mechanical performance and structural integrity in advanced composite applications.

The Neural-Network Quantum States (NNQS) method is rapidly emerging as a powerful tool in quantum mechanics. By combining variational Monte Carlo techniques with neural network-based variational functions, this approach leverages the remarkable advancements in deep learning achieved in recent years. While substantial progress has been made in simulating magnetic systems on lattices, simple molecules, and even continuous systems, the ab initio simulation of complex solid-state materials continues to pose significant challenges.
With the help of the Generalized Atomic Limit (GAL) - a recently developed model describing a system of quantum dots coupled to a superconducting lead - we attempt to show the efficiency and accuracy of NNQS, mainly the Restricted Boltzmann Machine (RBM), by comparing the acquired results to other available methods such as numerical renormalization group or exact diagonalization. The simultaneous study of the system’s properties such as the energy spectrum and quantum phase transitions could bring advancements in electronics, sensors or the design of high-quality qubits used in quantum computers.

The experimental alloys were prepared in a MAM-1 compact arc melter in an Ar protective atmosphere (purity 99.9999%) by adding the required amount of La to the induction-melted master alloy. The composition of the experimental alloys was selected from the LaNiSn phase diagram. The influence of microstructure and phase composition on the hydrogen absorption and desorption properties of these materials was studied.

The present study investigates the effect of titanium addition on the microstructure, phase composition, and functional properties of high entropy alloys (HEA). The motivation for the study is the potential for forming functional properties using alloy additives, which is of interest to many researchers. The base alloy (0.7AlCoCrFeNi) and three variants (0.05Ti, 0.2Ti, and 0.5Ti, respectively) were analyzed and the results compared to austenitic stainless steel. Erosion resistance tests were carried out in accordance with G76 at 90° and 30°. Microstructure and chemical composition analysis was conducted by SEM-EDS. Phase composition was determined by X-ray diffractometry (XRD), while hardness was measured using the Vickers method (HV0.5). The results showed a significant effect of Ti addition on the properties of the tested alloys. The microhardness increased from 300 HV0.5 for the alloy without Ti to 518 HV0.5 for the variant containing 0.5Ti. Moreover, the erosion resistance of the alloys was found to have improved, as the weight loss decreased from 3.33mg (0.7AlCoCrFeNi) to 2.9mg (0.7AlCoCrFeNi0.5Ti) at the 90° angle. Improvement in erosion resistance was also observed at the 30° angle, where the mass loss has changed from 4.93mg to 4.33mg with increasing content of Ti in the HEA alloy.
Phase composition analysis indicated the presence of two phases: α(FCC) and β(BCC). The increased Ti content reduced the relative volume of the α phase. SEM observations confirmed significant changes in microstructure associated with Ti addition, and EDS analysis confirmed the presence of Al, Ti, Cr, Fe, Co, and Ni elements.
The results obtained indicate that the addition of Ti can effectively improve the erosion resistance and hardness of HEA alloys, which may be important in applications that require increased wear resistance.

High-entropy alloys (HEAs) have gained significant attention among researchers due to their exceptional mechanical properties (including high hardness, strength and wear resistance), corrosion and oxidation resistance. The combination of these properties, along with good thermal stability, enables a considerable range of potential applications for HEAs. During the production and processing of HEAs, direct contact with refractory ceramic substrates is frequently encountered. However, research on the interactions between these substrates and HEAs remains limited. The present study aims to characterize the interactions between
Ni-Fe-Co-Cr high-entropy alloy and industrial ceramic substrates with Al2O3 (68.06-84.72 wt%) and SiO2 (12.94-25.83 wt%) as main components. The interaction was quantitatively described using contact angle measurements and evaluated through the axisymmetric drop shape analysis (ADSA) method, specifically utilizing the sessile drop technique. The experiments were conducted within the CLASIC high-temperature observation furnace. This approach enables the determination of wetting characteristics at elevated temperatures up to 1,600 °C. To prevent oxidation, the experiments were carried out in varying experimental conditions. The measurements were conducted either in a vacuum or under a slight overpressure of high-purity argon (> 99.9999 %). To gain further insights into the interfacial interactions, comprehensive post-experimental analyses of the HEA and ceramic substrates were performed. This included Scanning Electron Microscopy (SEM) for morphological evaluation and Energy-Dispersive Spectroscopy (EDX) microanalysis of chemical composition.

This study investigates the heat-treatment effect on the microstructure and hardness of the surface oxides of Ti-Zr-Nb alloys. X-ray diffraction results reveal that the Ti-Zr-Nb alloy exhibited a BCC structure. Hardness testing results show that the hardness of the Ti-Zr-Nb alloy gradually increases with the increase of heat-treatment time and approaches 1400 Hv after 60 min heat-treatment at 600 °C. X-ray photoelectron and energy-dispersive X-ray spectroscopy analyses show that the enhancing hardness of the alloys after heat treatment is attributed to the formation of the TiZrNbO4 oxide layer.

In this study, we investigated the effects of Ga additions (0, 0.5, and 1 wt.%) on the damping capacity of Cu-Al-Fe shape memory alloys. X-ray diffraction and differential scanning calorimetry results show that Cu-14Al-4Fe-xGa shape memory alloys undergo a β1(DO3)⇄γ1'(2H) phase transition. The martensitic phase transformation temperature decreases with the increase of Ga addition. Scanning electron microscopy observations indicate that the grain size gradually decreases with the increase of Ga addition. Hardness tests show that adding Ga into Cu-Al-Fe shape memory alloys does not affect the hardness of the alloys. Dynamic mechanical analysis results indicate that the damping capacity of the internal friction peak gradually decreases with the increase of the Ga content in the Cu-14Al-4Fe-xGa shape memory alloys. This is because grain refinement increases grain boundaries, hindering the interface movement between the martensitic and parent phase.

Currently, the focus of the waste Li-ion battery processing is on better separation of individual material components of the batteries so that this process is as efficient as possible. This step is closely related to the success of the subsequent processing of the individual separated components. The active material (black mass) after separation contains a certain proportion of metals in the form of their compounds and graphite. The paper deals with the possibility of separating a portion of selected metals, such as cobalt and nickel, into a separated fraction of the black mass using magnetic separation. The active material was annealed at 900 °C, whereby some of the metals were converted into a ferromagnetic state. The subsequent leaching converted the soluble salts into solution. A wet magnetic separation method was then used to concentrate the selected metals into the separated fraction. From the process, a mass fraction richer in the content of selected metals, a fraction richer in graphite and, after drying the solution after leaching, a proportion of salts including lithium salts was obtained. The success of the process depends on a number of parameters during leaching of the material and subsequent magnetic separation. This process made it possible to obtain a metal concentrate containing up to 60-70 wt.% cobalt and 2-3 wt.% nickel. The problem is to achieve better separation of individual components from the Li active material. Finding the best way to process waste lithium batteries is important for sustainable electromobility.

In the EU is currently implementing the Circular Economy (CE) base on sustainability and responsible manufacturing, characterized by 3xR= Reduce-Reuse-Recycle. In response to market demand, company Metall-Expres is developing “green” technologies for the production of high conductive oxygen-free copper busbars. Technology use self-produced Oxygen Free - Cu-OF copper wire which content up to 50% of internal waste and copper scrap from the secondary market. Busbars are produced using extrusion CONFORM® technique and drawing technique. Using the known skin effect in current transmission, it was undertaken to produce thinner busbars with a greater surface development than currently are manufactured. The thinnest profiles currently manufactured using CONFORM® extrusion technique are characterized by a thickness of 10 mm and width(a)/height(b) aspect ratio of 4 to 12. The research in the project aims to implement busbars with a thickness reduced by 40-50% and a/b of 12-33. The results presented in the current work include tests of busbars with a/b aspect ratio 12 (70x6 mm), 16 (80x5 mm) and 20 (100x5 mm). It was found that thin busbars are characterized by a similar skin factor kSE value as a thick profile with a comparable cross-section of the profile surface and a/b= 4 (40x10mm) in range of 1.046 to 1.063. However, differences in current transfer are noticeable for the temperature characteristics of the busbar with a/b= 20. Significant difference in heating during current transfer was found. The degree of heating is lower by over 5K from other, which translates into a reduction in resistance and thus an increase in current transfer efficiency. Mechanical tests of the busbars were also performed, confirming their compliance with the standards.
ACKNOWLEDGEMENTS
The authors gratefully acknowledge the funding of the Polish National Centre for Research and Development. The project was realized within the frames of the Program SMART, FENG.01.01-IP.01-000W/23- “Development of a technology for energy-saving copper busbars along with the implementation of a product innovation on the market”

Metallography optical supervision of microstructure by means of optical microscope ”LOMO MVT”, atomic-force microscopy (AFM) with high resolution were used. Ultrasound (US) impulse-phase method using computerized “KERN-4” with frequencies f┴ ≈ 0,7 MHz and f║ ≈ 1 MHz was used. The measured velocity error was equal to ΔV/V ≈ 1,5%.
2D, 3D atomic-force microscope microstructure of Ti (VT8) alloy after mechanical and thermal treatment is represented. The maximum internal friction (IF) Q-1M2 in Ti3Al at temperature TM2 » 440 K is discovered with activation energy value H2 = 0,85 ± 0,1 eV. The results of examinations of the relaxation processes in a crystalline lattice at hydrogen H, thermal and ultrasound processing on the temperature spectrum of internal friction and elastic module of Ti3Al alloy were explored. There was the relaxation maximum of internal friction Q-1m at ТМ ≈ 400 K, conditioned by the mechanism caused by reorientation of interstitial hydrogen atoms in dumbbell configurations H-H. Temperature dependence of internal friction Q-1(T) and elastic modulus E(T) (directional surface of anelastic-elastic body) and 2D, 3D atomic-force microscope microstructure of Ti (VT3) alloy after mechanical and thermal treatment are represented.
As a result of the mechanical study, the presence of a strong effect between polymers and multiwalled carbon nanotubes (MWCNTs) was confirmed.

Laser Powder Bed Fusion (LPBF)-produced CoCrFeNi multi-principal element (MPE) alloys exhibit a distinctive cellular microstructure with Cr-rich M23C6 carbides distributed along the cell boundaries. This study examines the anisotropic creep behavior of the alloy under high-temperature conditions, with creep tests conducted at temperatures ranging from 650°C to 800°C and applied stresses between 50 and 275 MPa. The results reveal significant anisotropy in creep rupture performance based on loading orientation, with samples tested along the build direction (BD) demonstrating substantially higher rupture lifetimes—one to two orders of magnitude greater—compared to those tested along the scan direction (SD). Stress exponent analysis further indicates higher values for BD samples (n ≈ 6) compared to SD samples (n ≈ 4), suggesting distinct deformation mechanisms influenced by orientation. Microstructural analysis using scanning transmission electron microscopy (STEM) shows that the cellular structure remains stable even after creep deformation, while Cr-rich nitrides and Mn-rich oxides evolve during high-temperature exposure, effectively impeding dislocation motion and enhancing creep resistance. The fractographic analysis highlights contrasting failure modes: BD samples exhibit ductile fracture features characterized by dimples, whereas SD samples display brittle fracture features with faceted morphologies. These observations underscore the critical role of LPBF-induced microstructural anisotropy in governing creep behavior and fracture mechanisms. The findings provide valuable insights for optimizing MPE alloys for applications in extreme environments requiring superior high-temperature performance.

For finished products, it is sometimes necessary to measure hardness with minimal surface disturbance, where the indentations should not be visible to the naked eye. Applied loads that meet this requirement are below 0.9807 N for common metals. In this load range, the Vickers method is usually affected by the indentation size effect (ISE), which makes it difficult to interpret the measured values. If this effect is not taken into account, the measurement results can be misleading. For this reason, we recommend using the “true hardness”, which is determined using the method presented. This article presents a method for calculating the “true hardness”, which is not influenced by the test force when measuring the microhardness and essentially corresponds to the Vickers macrohardness. Measurements were made using a Hanemann microhardness tester at loads in the range of 0.09807 N and 0.9807 N. The size and nature of the ISE and subsequently the “true hardness” were evaliated using Meyer’s power law (index n), the Proportional Sample Resistance (PSR) and the Hays-Kendall method. The measurements were carried out on commonly used non-ferrous metals: Al, Mg, Cu, Ti, Ni, Co and W. A certain limitation of the method is that measurements must be taken on a metallographically polished surface, the quality of which influences the ISE parameters and consequently the “true hardness”.

Many ferroalloy production problems in South Africa are formulated around an objective function to optimize
the smelting process. However, it is essential to consider the broader objective around these challenges: Is
South Africa’s ferroalloy industry prepared to transition towards more sustainable metallurgy practices in the
face of increasing environmental challenges? Can renewable biomass, derived from agricultural by-products,
serve as an effective alternative to traditional fossil-based reductants for ferroalloy production? In 2022,
global ferromanganese production was approximately 5.08 million metric tons. However, conventional
smelting practices rely on fossil-based fluxing agents, contributing to significant carbon emissions, estimated
between 1.8 to 6.0 metric tons of CO₂ per metric ton of ferromanganese produced. This study investigates
biomass-derived additives, specifically, brewery spent grain, sugarcane bagasse, and macadamia nut shells,
as sustainable alternatives for slag modification in ferromanganese production. Experimental work used a
tube furnace to simulate smelting conditions, with biochar produced through pyrolysis and analyzed for its
effects on slag behavior. Characterization techniques such as X-ray diffraction (XRD), scanning electron
microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX) were employed to assess the phase
composition and morphology, while metal recovery efficiency was evaluated using inductively coupled
plasma mass spectrometry (ICP-MS) and atomic absorption spectroscopy (AAS). This research aims to
provide insights into biomass-based fluxing agents' feasibility, supporting sustainable metallurgical practices
and reducing the ferroalloy industry’s carbon footprint. The findings are expected to enhance slag properties,
improve metal recovery, and contribute to a more sustainable smelting process.

Nickel-based superalloys are playing a crucial role in various industrial applications within the chemical, petrochemical, energy, and aerospace sectors, where they must withstand extreme conditions requiring exceptional mechanical strength and corrosion resistance at high temperatures. This study examines the high-temperature deformation behaviour of the Inconel 925 superalloy by evaluating its deformability and microstructural evolution in the 1050 - 1200°C temperature range. Microstructural changes were analysed using X-Ray Diffraction (XRD) and Scanning Electron Microscopy - Electron Backscatter Diffraction (SEM-EBSD) techniques, while deformability was assessed through the upsetting method using a gravity-drop hammer. Experimental data on deformation resistance, specific mechanical work, and plasticity were collected and analysed as functions of deformation temperature and impact energy. The findings show that increasing the deformation temperature improves plasticity. Furthermore, a detailed analysis of the plasticity increase rate as a function of impact energy revealed that higher impact energy results in a more pronounced rise in plasticity. Additionally, deformation resistance decreases with increasing temperature across all impact energy levels. A similar trend was observed for specific mechanical work, which declines as deformation temperature rises, regardless of impact energy.

Acknowledgments
This work was supported by a grant from the Ministry of Research, Innovation and Digitization (Romania), CCCDI-UEFISCDI, project number PN-IV-P7-7.1-PTE-2024-0364, contract no. 3PTE / 2025, within PNCDI IV.

Ni-, Ni-Fe-, and Co-based superalloys have been widely used in high-temperature applications due to their excellent mechanical strength, creep resistance, and corrosion resistance. In particular, Co-based superalloys exhibit superior corrosion resistance compared to their Ni-based counterparts, making them suitable for components exposed to elevated temperatures under moderate static or cyclic loading conditions. However, their high hardness and strength significantly limit machinability, increasing production costs.

To address these challenges, additive manufacturing (AM) has emerged as a promising approach, enabling the fabrication of complex geometries with reduced material waste. This study examined the feasibility of producing the Co-based superalloy Mar-M-509A using laser beam powder bed fusion (LB-PBF), followed by post-processing heat treatments. The influence of key LB-PBF process parameters on the relative density of the printed components was investigated, and the effects of heat treatment and hot isostatic pressing (HIP) on the microstructure and mechanical properties were evaluated.

Experimental results showed that stress-relief heat treatment resulted in a yield strength of up to 980 MPa with an elongation of 6.5%, whereas HIP reduced the yield strength to 730 MPa but significantly improved ductility, increasing elongation to 9.9%. Microstructural analysis revealed that HIP effectively eliminated porosity and refined the grain structure, leading to enhanced mechanical performance. These findings demonstrate the potential of post-processing treatments to optimize the properties of LB-PBF-fabricated Co-based superalloys for high-temperature applications.

The bell for the Břevnov Monastery was cast in 1313. In May 1945, it was hit by a fire during the Prague Uprising and subsequently broken. The preserved fragments of the bell from the Břevnov Monastery were investigated using chemical and microstructural analysis and the changes caused by the increased temperature during the fire were monitored. The changes in other properties (hardness and corrosion resistance) caused by the fire were also compared.

Zirconium and its alloys are widely utilised in various industries, from nuclear reactors to biomedical implants, owing to their excellent corrosion resistance, low neutron absorption cross-section, and superior mechanical properties. The low neutron absorption cross-section, in particular, makes zirconium an ideal structural material for nuclear reactor components. To enhance the material's mechanical strength and achieve a favourable microstructure comprising hexagonal close-packed (hcp) α-phase and body-centred cubic (bcc) β-phase, new zirconium alloys have been developed. The studied alloy, Zr-4Nb-2Al, contains a high concentration of α-phase-stabilising aluminium and β-phase-stabilising niobium, resulting in a favourable α+β microstructure.
This study examines the microstructural changes in the Zr-4Nb-2Al alloy during thermomechanical processing using hot rotary swaging. A key focus of the research was analysing the phase transformations occurring in the alloy, which were studied using differential scanning calorimetry and resistometry. These methods provided insight into the α-to-β phase transformation, which was later used to establish the temperature parameters for hot rotary swaging. The swaging process began in the β-phase region to refine the typically large β grains. This was followed by processing in the α + β coexistence region to achieve the desired final microstructure.
The microstructural changes after each processing step were analysed using scanning electron microscopy, which revealed a transition from a lamellar to a globular microstructure. Mechanical properties were then evaluated through compression and microhardness tests, demonstrating the material's performance enhancement.
This research provides insight into the steps involved in the hot rotary swaging of zirconium alloys. It also offers a detailed summary of the microstructural and mechanical property changes that occurred during the thermomechanical processing of the Zr-4Nb-2Al alloy.

Due to its mechanical properties and biodegradability, AZ31 magnesium alloy is being considered as a potential material for ureteral stents. This work focuses on the interaction of AZ31 alloy with artificial urine to assess its corrosion resistance. Samples of AZ31 alloy were immersed in artificial urine for different lengths of time and then their corrosion degradation was evaluated. Scanning electron microscopy (SEM) with energy dispersive spectrometer (SEM-EDS) and Fourier transform infrared spectrometry (FTIR) were used for surface characterization and identification of corrosion products. Electrochemical behavior was determined by potentiodynamic polarization. The results showed that the degradation of AZ31 in artificial urine decreased over time. The thickness of the corrosion products reached up to 20 micrometers after one week. The corrosion products were mainly composed of phosphates. AZ31 alloy appears to be a suitable candidate for the study of magnesium ureteral stents.

Magnesium Mg and its alloys are attractive materials in industries such as automotive and aerospace. However, their use is often limited by their susceptibility to corrosion. One way to improve the corrosion resistance of these materials is to apply protective coatings. In this work, we focus on the preparation of plasma electrolytic oxidation (PEO) with zeolitic imidazolate framework-8 (ZIF-8) particles on AZ31 magnesium alloy. ZIF-8 particles were prepared by in-situ method on PEO coating at different times under laboratory temperature. The presence of ZIF-8 particles was characterized by scanning electron microscopy with an energy dispersive spectrometer (SEM-EDS). The corrosion properties were characterized by potentiodynamic polarization in 0.9% NaCl. The results showed that ZIF-8 particles were successfully prepared and their uniform distribution on PEO coating increased with time. The preparation of ZIF-8 particles improved the corrosion properties of PEO coating, and the best corrosion resistance was observed when the particles grew for 48 h.

This study examines the impact of two three-step hot forging processes, (F30-60-40) and (F30-60-80), on the microstructure of the Al0.35CoCrFeNi high entropy alloy. A numerical simulation of the hot forging process was employed to predict the evolution of grain formation. The simulation model was calibrated and validated using experimental compression data from the as-cast alloy prior to forging, ensuring the accuracy of the model in predicting microstructural changes. In the forged states, the alloy exhibited a single-phase face-centered cubic (FCC) structure. During the third forging step of the F30-60-40 process, a uniform distribution of dynamically recrystallized equiaxed grains with a median grain size of 64±1 μm was observed. However, after the F30-60-80 forging process, dual grain size was observed in the sample, which could be attributed to the increased energy applied during the third forging step. The correlation between temperature, equivalent stress, equivalent plastic strain, and the resulting microstructure was analyzed. The simulations enabled the prediction of regions within the samples where dynamically recrystallized grains were formed. The study highlights the relationship between the forging process and the resulting microstructure, providing crucial information for optimizing the hot forging process to achieve desired material properties.

Complex-concentrated alloys (CCAs) are an emerging class of materials known for their excellent mechanical and thermal stability. However, their deformation behavior, particularly the interplay between microplasticity and dynamic strain aging (DSA), remains an area of active research. We investigate the microplasticity and serrated flow behavior of an equiatomic FeAlCrMo CCA under compression at elevated temperatures. By coupling conventional mechanical testing with in-situ acoustic emission (AE) monitoring, we identify microplastic events occurring early in the quasi-elastic regime and analyze their statistical characteristics. Our results confirm the presence of DSA, manifesting as the Portevin-Le Châtelier (PLC) effect, with distinct strain rate and temperature dependencies. The AE data reveal power-law scaling in the magnitude of plastic events, indicative of dislocation avalanche dynamics. Notably, this scale-invariant behavior is observed not only during macroscopically plastic deformation but also in the microplastic regime, suggesting self-organized criticality in dislocation motion. These findings extend the current understanding of plasticity in CCAs and emphasize the need for further exploration of their deformation mechanisms.

Metallic materials have made possible technological developments over thousands of years. The increased demand for structural nickel alloys in critical areas such as energy, construction, and safety are expected to drive production growth rates of up to 200 percent in 30 years. However, most of these materials take a significant amount of energy to extract and manufacture, and these processes create substantial volumes of greenhouse gases and pollutants. So, this study was done with the aim of enhancing nickel alloy reuse and examining recycled materials in the corrosion environment of supercritical carbon dioxide. The materials tested were Ni-base alloys Inconel 738 and Inconel 713. The recycled content of the newly created alloy was 50 percent and 100 percent. These specimens were then exposed to 1000 hours of loop operation at a maximum operating temperature of 550 °C and a maximum operating pressure of 25 MPa, with a constant flow rate of sCO2 medium of 0.1 kg/s. The specimen surface, corrosion layer thickness and composition were evaluated by Scanning Electron Microscope (SEM) with Energy Dispersive Spectroscopy (EDS).

Quantum computing is currently emerging as a useful paradigm for solving highly complex computational problems. Current quantum computers are unfortunately too noisy to provide sufficient accuracy, and quantum-classical hybrid algorithms emerged as a solution. Variational Quantum Deflation (VQD) has gained significant attention for addressing challenges in quantum chemistry, material science, etc. VQDs typically use multiple optimization methods, and the correct choice of optimization method can significantly impact performance. In our study, we focused on the comparison of multiple optimization methods used in VQD when applied to the electronic structure of crystals. The quantum part of VQD ran on a classical simulator with imported noise models from real quantum computers from the IBM Quantum Platform.

The authors acknowledge the financial support from the Czech Academy of Science, in particular the Praemium Academiae of M. F. The computational resources were partly provided by the Ministry of Education, Youth and Sports of the Czech Republic under the Projects e-INFRA CZ (ID:90254) at the IT4Innovations (IT4I) National Supercomputing Center in Ostrava (Czech Republic), and e-Infrastruktura CZ (e-INFRA, ID:90254) at the MetaCentrum and the CERIT Scientific Cloud in Brno (CZ). The authors are also very grateful for using the IBM Quantum Platform infrastructure for the simulations and the noise model that was also provided by the IBM.

The La-Ni binary system, and in particular the LaNi5 binary intermetallic phase, has been intensively studied in recent decades, especially as a promising hydrogen storage material. Knowledge of phase equilibria is very important for the possible optimization of material properties. This work is focused on the study of the thermodynamic properties of the La2ni7 phase, which occurs in phase equilibrium with the LaNi5 phase and can therefore influence the capacity and dynamics of these hydrogen storage materials in real materials. The alloy samples were prepared from pure elements using a gravity melting furnace in an inert Ar6N atmosphere. The overall composition and chemical composition of the phases were analyzed by SEM-EDX. The crystal structure of the phases was confirmed by powder XRD.
Our experiments were complemented by quantum-mechanical calculations implementing the density functional theory (DFT) within the generalized gradient approximation (GGA) to determine the ground-state structural, electronic, thermodynamic, and elastic properties of La2Ni7. A computational unit cell of La2Ni7 contains 36 atoms and has a strongly anisotropic shape. The computed results obtained for static lattices indicate that La2Ni7 is thermodynamically stable with respect to the decomposition into elemental end members. The stress-strain method was used to address the mechanical stability by computing a full tensor of the second-order elastic constants and La2Ni7 has been found to be mechanically stable.
Acknowledgments
This study is a part of the project No. CZ.02.01.01/00/22_008/0004631 Materials and technologies for sustainable development within the Jan Amos Komensky Operational Program financed by the European Union and from the state budget of the Czech Republic. The authors acknowledge INFRA CZ (ID:90254) at the IT4Innovations National Supercomputing Center and e-Infrastruktura CZ (e-INFRA LM2018140) at the MetaCentrum as well as CERIT Scientific Cloud and project CZ.02.01.01/00/22_008/0004572.

Nickel heat-resistant alloy with a cast directional structure ZhS32 is the alloy for aviation and works in operating conditions 1000-1050°С. The positive experience of practical operation of the microplasma powder welding deposition (MPWD) process with Ni-based superalloy ZhS32 on aircraft blades at the E.O. Paton Electric Welding Institute were confirmed. The thermal deformation parameters of crystallization in the deposition process are very different from the parameters of directional crystallization during the base metal blade manufactories, therefore, the the specified structures are investigated taking into account the tendency to a low-plastic state or the hot cracking in some manufacturing parameters.
The study examined the ZhS32 alloy's structural states after deposition “as-built” and after follow heat treatments, that usually used for directional crystallized ZhS32. Base metal samples were similarly tested after homogenization and after following two-stage aging. The dispersion and particular location of carbides and the strengthening phase, the presence and state of grain boundaries depending on the heat treatment modes were investigated.
A set of mechanical tests for short-term strength was determined for the same samples. It consisted of the critical fracture strain (εcr) and tensile strength as functions of temperature according to the original method, obtained with longitudinal static tensile testing within 20-1100°C temperature range. In addition, these dependencies are investigated as a discrete simulation of the response of the base metal and determined metal tensile strength to the welding thermal deformation cycle. The same properties are given for the base metal ZhS32 comparatively.
The results provide new insights into the causes and regularities of hot crack formation during fusion welding of nickel-based superalloys, expanding upon previous findings .