1. Harmonizing microstructures and enhancing mechanical resilience : novel powder metallurgy approach for Zn–Mg alloysAnna Boukalová, Jiří Kubásek, David Nečas, Peter Minárik, Črtomir Donik, Drahomír Dvorský, Dalibor Vojtěch, Alena Michalcová, Matjaž Godec, Irena Paulin, 2024, original scientific article Abstract: Zinc alloys are recognised for their excellent biocompatibility and favourable corrosion rates, making them suitable for bioabsorbable implants. However, their mechanical properties necessitate improvement to fulfil the rigorous requirements of biomedical applications. This research focuses on engineering pseudo-harmonic structures within zinc alloys through a comprehensive method combining mechanical alloying, spark plasma sintering, and hot extrusion techniques. This fabrication process results in a composite material characterised by a soft core surrounded by a continuous, three-dimensional, ultrafine-grained hard shell. The experiment involved blending pure zinc with Zn–1Mg alloy powder, leading to the formation of both ductile zinc and fine-grained Zn–1Mg regions. While the Mg2Zn11 intermetallic phase was found to enhance the alloy's mechanical strength, the presence of oxide shells adversely affected the material's properties. The elimination of these shells via hot extrusion markedly improved the alloy's tensile strength, reaching an average value of tensile strength of 333 ± 7 MPa. This study provides significant insights into the material engineering of zinc-based alloys for biodegradable implant applications, demonstrating a viable approach to optimising their mechanical performance. Keywords: zinc, magnesium, biodegradable, powder metallurgy, harmonic structure Published in DiRROS: 23.07.2024; Views: 141; Downloads: 138
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2. Microstructural, corrosion and mechanical properties of a WE43 alloy : conventional extrusion versus SPDAnna Dobkowska, Aleksandra Zielińska, Irena Paulin, Črtomir Donik, Milena Koralnik, Bogusława Adamczyk-Cieślak, Monika Wieczorek-Czarnocka, Dariusz Kuc, Jiří Kubásek, Tomasz Mikuszewski, Matjaž Godec, Jarosław Mizera, 2024, original scientific article Abstract: A hexagonal close-packed-structure WE43 alloy was extruded without any preheating of the initial billet using extrusion with an oscillating die to improve the corrosion and mechanical properties. The WE43 alloy was extruded at high ratios of R 1 5:1, R 2 7:1 and R 3 10:1. Electron back-scatter diffraction and transmission electron microscopy were used to determine the microstructural properties of the alloys. The influence of the extrusion method and the extrusion ratios on the corrosion and mechanical properties were investigated. Electrochemical tests were performed, and the corrosion damage was inspected. Tensile tests were made using micro specimens. When compared to conventional extrusion, the microstructural changes obtained with the KoBo method at R 5:1 increased the corrosion resistance, which was not only due to the grain refinement, but also due to the intensity of the texture. A decline in the corrosion resistance of the alloys deformed at higher extrusion ratios was observed. This was a result of the massive plastic strain imposed by the KoBo die. The room-temperature mechanical properties of the KoBo-extruded alloys were improved. However, at higher temperatures the mechanical properties decreased due to the solutioning of tiny triple precipitates. Keywords: WE43, several plastic deformation, microstructure, corrosion, mechanical properties Published in DiRROS: 23.07.2024; Views: 120; Downloads: 39
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3. Exploring the microstructure, mechanical properties, and corrosion resistance of innovative bioabsorbable Zn-Mg-(Si) alloys fabricated via powder metallurgy techniquesDavid Nečas, Vojtěch Hybášek, Jan Pinc, Andrea Školáková, Ilona Voňavková, Klára Hosová, Martin Zlámal, Anna Boukalová, Jan Pokorný, Drahomír Dvorský, Črtomir Donik, Dalibor Vojtěch, Jiří Kubásek, 2024, original scientific article Abstract: Zinc alloys belong to the widely studied materials for applications like medical devices, however, they often
encounter an inappropriate combination of mechanical/corrosion/biological properties. In this respect, we
produced the Zn–1Mg and Zn–1Mg–1Si containing biologically friendly elements with potential strengthening
effects on zinc matrix by powder metallurgy methods including mechanical alloying, spark plasma sintering, and
extrusion further enabling the formation of materials with unique extremely fine-grained microstructures. The
systematic study of these materials showed the possibility of reaching homogeneous nano-grain microstructure
and high strength values exceeding 450 MPa in tension. Selected chemical composition and processing methods
led also to slightly decreased wear and corrosion rates and rather uniform corrosion. Keywords: zinc, mechanical alloying, biodegradable metals, composite, spark plasma sintering, extrusion, powder metallurgy Published in DiRROS: 23.07.2024; Views: 121; Downloads: 120
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4. Microstructure and properties of an AZ61 alloy after extrusion with a forward-backward oscillating die without preheating of the initial billetAnna Dobkowska, Aleksandra Zielińska, Irena Paulin, Črtomir Donik, Maciej Łojkowski, Milena Koralnik, Bogusława Adamczyk-Cieślak, Krystian Paradowski, Marek Tkocz, Dariusz Kuc, Jiří Kubásek, Matjaž Godec, Wojciech Święszkowski, 2023, original scientific article Keywords: magnesium alloys, severe plastic deformation, microstructure, mechanical properties, corrosion, extrusion, high deformation ratio Published in DiRROS: 17.05.2024; Views: 286; Downloads: 179
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5. Characterization of hFOB 1.19 cell line for studying Zn-based degradable metallic biomaterialsEva Jablonská, Lucie Mrázková, Jiří Kubásek, Dalibor Vojtěch, Irena Paulin, Tomáš Ruml, Jan Lipov, 2024, original scientific article Abstract: In vitro testing is the first important step in the development of new biomaterials. The human fetal osteoblast cell line hFOB 1.19 is a very promising cell model; however, there are vast discrepancies in cultivation protocols, especially in the cultivation temperature and the presence of the selection reagent, geneticin (G418). We intended to use hFOB 1.19 for the testing of Zn-based degradable metallic materials. However, the sensitivity of hFOB 1.19 to zinc ions has not yet been studied. Therefore, we compared the toxicity of zinc towards hFOB 1.19 under different conditions and compared it with that of the L929 mouse fibroblast cell line. We also tested the cytotoxicity of three types of Zn-based biomaterials in two types of media. The presence of G418 used as a selection reagent decreased the sensitivity of hFOB 1.19 to Zn2+. hFOB 1.19 cell line was more sensitive to Zn2+ at elevated (restrictive) temperatures. hFOB 1.19 cell line was less sensitive to Zn2+ than L929 cell line (both as ZnCl2 and extracts of alloys). Therefore, the appropriate cultivation conditions of hFOB 1.19 during biomaterial testing should be chosen with caution. Keywords: zinc degradable materials, in vitro cytotoxicity testing, hFOB 1.19 osteoblasts Published in DiRROS: 28.02.2024; Views: 353; Downloads: 123
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6. The evolution of microstructure and mechanical properties of Zn-0.8Mg-0.2Sr alloy prepared by casting and extrusionJiří Kubásek, Jan Pinc, Klára Hosová, Markéta Straková, Orsolya Molnárová, Jan Duchoň, David Nečas, Miroslav Čavojský, Matjaž Godec, Irena Paulin, 2022, original scientific article Keywords: zinc, magnesium, biodegradable, microstructure, mechanical properties, texture Published in DiRROS: 06.05.2022; Views: 962; Downloads: 288
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