Laser-assisted development of new Ti-Mo-Zr alloys for biomedical applications

Ti-alloys used in prosthetic applications are mostly alloys initially developed for aeronautical applications, so their behavior was not optimized for medical use. A need remains to design new alloys for biomedical applications, where requirements such as biocompatibility, in-body durability, specific manufacturing ability, and cost effectiveness are considered. Along with excellent biocompatibility, ductility and toughness materials for this application must present fatigue, wear and corrosion resistance, and a large processing window. Laser manufacturing methods are increasingly being used to produce customized implants. In this study, variable powder feed rate laser cladding has been used as a combinatorial method for investigating new alloys. It offers a unique possibility for the rapid and exhaustive preparation of a whole range of alloys with compositions variable along a single clad track. The method was used to produce composition gradient Ti-Mo-Zr alloys. The aim is to produce fully β -phase alloys with low elastic modulus in order to allow minimizing stress shielding and bone resorption. Alloy tracks with compositions in the range 0-10 wt.% Mo and 0-30wt.% Zr were produced and characterized as a function of composition using micro-scale testing procedures for screening of compositions with promising properties. Microstructural analysis showed that alloys with Mo and Zr contents above 5% are fully formed of β-phase. Ultramicroindentation tests showed that Ti-8Mo-19Zr alloys presented low values of hardness and Young’s modulus (78 GPa) that are closer to that of bone than common Ti alloys, thus showing great potential for implant applications.