Combinatorial search for Ti–Ni–Hf high formable shape memory alloys

Abstract

In this study, we searched for Ti–Ni–Hf high formable shape memory alloys (HFSMAs) using combinatorial methods. By adding Hf to Ti–Ni SMAs, the potential is that Ti–Ni SMAs become metallic glasses. For efficient material search, the glass transition temperature was evaluated through combinatorial measurement of electrical resistance during crystallization. From the results, we searched for Ti–Ni–Hf HFSMAs, which undergo glass transition in the amorphous state. Ni-rich Ti–Ni–Hf thin-film amorphous alloys with more than 10 at% Hf content became thin film metallic glasses, whereas Ni-poor samples did not. Further, we evaluated the effect of annealing temperature on the martensitic transformation temperature of Ti–Ni–Hf SMAs using combinatorial methods. From the results, we measured the reverse transformation start temperature A s at 368–404 K, and it varied with the annealing temperature and Hf composition.