ABSTRACT
Shape memory alloys (SMAs) and superelastic (SE) alloys are critical materials among the issues of the urgently demanded biomedical applications and biomaterials. In this chapter, a series of highly potential near-eutectoid Ti-4Au-5M (mol%) (M = transition metals of V, Cr, Mn, Fe, Co, Ni, Cu, and Mo) specimens were systematically explored. Specimens were prepared by physical metallurgy procedures and were evaluated by XRD measurements, microstructure observations, chemical composition analysis, bending examinations, tensile examinations, and so on. Outstanding shape memory effect (SME) exhibiting around 94% shape recovery rate (SR%) was discerned in the Cr element introduced Ti-4Au-based alloy. Furthermore, as the introduced third elements V, Cr, Mn, and Mo, the Ti-4Au-based ternary specimens exhibit slight pseudoelastic (PE) behavior. While no PE is found when the introduced third metals are Fe and Co elements, respectively. Based on the investigations of mechanical behavior, the introduced third metals Cr, Mn, and Mo could be categorized as the optimized group. Judging from the evaluations of their mechanical behavior, SME, and SE effect, respectively, these alloys clearly surpass others. In brief, first, this study systematically investigated the effects of transition metals on the mechanical and functional behaviors of the near-eutectoid Ti-4Au-5M (mol%) SMAs. Second, the Cr-introduced alloy, which is sorted as the optimized group, was further subjected to the manipulation of its chemical composition. Last, fine tailoring of the Ti-4Au-5Cr-based ternary alloy was done by an introduction of the Ta element, which possesses high X-ray contrast and is suitable for biomedical applications. Through step-by-step optimizations, the mechanical behaviors and functionalities of these SMAs have been greatly enhanced. These findings could be guidelines for further investigations of the Ti-4Au-based alloys.
