Rare earth elements are known to improve both mechanical and corrosion properties. However, it highly depends on the final microstructure conditions of prepared material. During extrusion, intermetallic phases may be redistributed, partially dissolved or on the contrary, precipitated. The knowledge of the impact of extrusion on the individual alloys is therefore essential for their application. In this work, three magnesium alloys (Mg-4Y-3RE, Mg-2Y-1Zn, Mg-3Nd-0.5Zn) were prepared by an extrusion process. Microstructure, mechanical and corrosion properties were compared with extruded pure Mg. The advantages and disadvantages of individual alloys are discussed. Based on the obtained results, the Mg-4Y-3RE alloy seems to exert the best mechanical and corrosion properties. Other materials were characterised with anisotropy of mechanical properties and much higher corrosion rate.

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As the commercially most-used Ti-6Al-4V alloy has a different modulus of elasticity compared to the modulus of elasticity of bone and contains allergenic elements, β-Ti alloy could be a suitable substitution in orthopedics. The spark plasma sintering (SPS) method is feasible for the preparation of materials, with very low porosity and fine-grained structure, leading to higher mechanical properties. In this study, we prepared quaternary Ti-25Nb-4Ta-8Sn alloy using the spark plasma sintering method. The material was also heat-treated in order to homogenize the structure and compare the microstructure and properties in as-sintered and annealed states. The SPS sample had a modulus of elasticity of about 63 ± 1 GPa, which, after annealing, increased to the value of 73 ± 1 GPa. The tensile yield strength (TYS) of the SPS sample was 730 ± 52 MPa, ultimate tensile strength (UTS) 764 ± 10 MPa, and ductility 22 ± 9%. Annealed samples reached higher values of TYS and UTS (831 ± 60 MPa and 954 ± 48 MPa), but the ductility decreased to the value of 3 ± 1%. The obtained results are discussed considering the observed microstructure of the alloy.

Nowadays there is a high trend and effort to find a suitable biodegradable metal, whose mechanical properties would be the same or higher to those of currently used biomaterials. Current biomaterials, such as stainless steels, cobalt-chromium alloys, and titanium alloys have superior mechanical properties, machinability, and durability, but are considered nondegradable, and long-term clinical complications may occur. Their biggest disadvantage is that the patient must have undergone a second removal surgery. Therefore, new biodegradable materials have been developed to eliminate the shortcomings of current biomaterials. Magnesium (Mg), iron (Fe) and zinc (Zn) based alloys have been proposed as biodegradable metals for medical application. Iron-based alloys show good mechanical properties compared to magnesium-based alloys. However, both of them exhibit bad corrosion properties, because the degradation rate of magnesium has proven to be high. On the other hand, the degradation of iron-based alloys is too slow in a physiological environment. The corrosion attack of both materials is not typically uniform. Therefore, zinc is proven to be a promising material for this application.

Ti-6Al-4V alloy is the most commercially used material for the production of orthopedic implants. However, despite its excellent properties, it is not an ideal material for use in medicine in terms of vanadium toxicity and relatively high modulus of elasticity. Titanium β-alloys could be a suitable replacement in future years for Ti-6Al-4V alloy, as they have a lower modulus of elasticity and contain non-toxic elements. Some of the alloying elements may even increase the biocompatibility of the alloy. In addition, a progressive 3D printing method would allow custom-made implants with the required properties to be printed. The aim of this work was to characterize the β alloy Ti-30Nb by Selective Laser Melting (SLM) method and to determine its mechanical properties. In addition, heat treatment was applied in order to homogenize the structure. Ti-30Nb alloy was compared in as-built state and in annealed state.