Phase constituent and microstructure manipulations via annealing for enhancements of mechanical property and functionalities of Ti–Au–Cr–Ta biomedical shape memory alloys

Abstract

Shape memory alloys (SMAs) are considered as one of the most important smart materials for the future biomedical applications in consideration of the rapid world population aging. The promising Ti–Au–Cr–Ta alloys, which are good in biocompatibility, excellent in X–ray contrast, and high in corrosion resistance, were synthesized and evaluated in this study for realizing new biomedical materials. The specimens with the specific chemical composition of Ti–4Au–5Cr–5Ta (at.%) were chosen as the target material based on our preliminary findings. The Ti–4Au–5Cr–5Ta alloys were thereafter subjected to annealing–treatments at various annealing time periods for the manipulations of the phase constituents and microstructures. The fundamental mechanical properties and functionalities, such as shape deformation/recovery behaviors in the loading/unloading processes, were investigated. The two optimized specimens, which were subjected to a 1073 K annealing–treatment for 1.8 ks and 3.6 ks, performed good mechanical properties (i.e., strength and elongation) and excellent shape recovery rate of 96 % and 97 %, respectively. Via the systematic fine–tuning strategies, the Ti–4Au–5Cr–5Ta alloy with appropriate heat–treatment surpassed all other Ti–Au–Cr–Ta alloys, which were study by our research group.