Two-Way Shape Memory Effect and Its Stability in a Ti–Ni–Nb Wide Hysteresis Shape Memory Alloy

The effect of training strain, deformation temperature and number of training cycles on the two-way shape memory effect (TWSME) and its stability have been investigated systematically in a Ti46.3Ni44.7Nb9 (at%) wide hysteresis shape memory alloy (SMA). The experimental results indicate that two-way shape memory strain increases with increasing the training strain up to 14.5% and then decreases with further increasing the training strain. When the training strain is less than 12%, the two-way shape memory strain increases with the increase of number of training cycles in the Ti46.3Ni44.7Nb9 alloy deformed at the room temperature. Compared with TiNi binary alloy, the TWSME is smaller and the training strain to get the maximum TWSME is larger in the Ti–Ni–Nb alloy due to the deformation of (beta)-Nb soft particles during training. However, the Ti–Ni–Nb alloy exhibits excellent stability of TWSME during the thermal cycling.