Influence of copper content and thermal treatment on shape memory effect in rapidly quenched TiNiCu alloys

Amorphous alloys of the TiNi - TiCu system with a copper content of 25 to 40 at.% were prepared by planar flow casting at a melt cooling rate of 106 K/s. Crystallization of the alloys was carried out by isothermal annealing and by action of single electric pulse with a duration of 5 ms. Shape memory behavior and structure of the alloys was investigated by means of bending tests and X-ray phase analysis. It was found that increasing the copper content to above 30 at.% considerably reduces the plasticity and shape memory effect of the alloys. However, abrupt decreasing the annealing duration significantly improves the shape memory performance due to prevention of the formation of brittle Ti-Cu phases in the alloys structure.