Two-way shape memory effect and its stability in
Ti-Ni-Hf high temperature shape memory alloy
Ti-Ni-Hf high temperature shape memory alloy
(School of Materials Science and Engineering, Harbin Institute of Technology,
Harbin 150001, China)
Harbin 150001, China)
Abstract: The two-way shape memory effect(TWSME) in a Ti36Ni49Hf15 high temperature shape memory alloy(SMA) was systematically studied by bending tests. In the TiNiHf alloy, the martensite deformation is an effective method to get two-way shape memory effect even w, ith a small deformation strain. The results indicate that the internal stress field formed by the bending deformation is in the direction of the preferentially oriented martensite variants formed during the bending deformation. Upon cooling the preferentially oriented martensite variants form under such an oriented stress field, which should be responsible for the generation of the two-way shape memory effect. Proper training process benefits the formation of the oriented stress field, resulting in the improvement of the two-way shape memory effect. A maximum TWSME of 0.88% is obtained in the present alloy.
Key words: TiNiHf alloy; high temperature shape memory alloy; two-way shape memory effect; training; stability