Search for Ti–Ni–Zr thin film metallic glasses exhibiting a shape memory effect after crystallization

We conducted a search for Ti–Ni–Zr thin film metallic glasses (TFMGs) exhibiting a shape memory effect after crystallization. We investigated the possibility of (Ti, Zr)(100−x)–Nix thin film amorphous alloys exhibiting a glass transition. All prepared samples were classified into three groups such as Ti-rich (x < 50), equiatomic (50 < x < 51) and Ni-rich (x > 51) samples. Equiatomic Ti–Ni–Zr thin film amorphous alloys with Zr content ranging from 11 to 17 at.% showed a glass transition, and thus were concluded to be TFMGs. Several Ni-rich samples exhibit glass transition and were also TFMGs. On the other hand, Ti-rich samples did not exhibit a glass transition irrespective of the Zr content. Moreover, we investigated the shape memory behavior of crystallized TiNiZr TFMGs. Ti39Ni50Zr11 TFMGs annealed at 973 K for 3.6 ks exhibited a martensitic transformation from the B2 to the B19′ phase upon cooling and heating. The martensitic phase start temperature and reverse martensitic phase start temperature were 296 and 352 K, respectively. In addition, this alloy showed good shape memory behavior, achieving recovery strain of 2.5% and a critical stress for slip of 500 MPa.