Influence of Cyclic Deformation on Shape Memory Characteristics of Ti-Ni-Cu Alloys Fabricated by Pulse-Current Pressure Sintering Method

Ti-Ni-Cu shape memory alloy by elemental powders was fabricated by using a pulse-current pressure sintering method, and it was subjected to solid-solution heat treatment after sintering to homogenize the microstructure of the alloy. The influence of the thermo-mechanical cyclic deformation on the shape memory and thermo-mechanical characteristics of Ti-Ni-Cu alloy was investigated. The thermo-mechanical cyclic deformation improved the deformation behavior of the sintered alloy and made the thermo-mechanical behavior of the alloy stable caused by the introduction of dislocations. As a result, the recovery stress of the alloy after the cyclic deformation fairly increased. The transformation temperatures of the alloy after the cyclic deformation became lower than those of the alloy before the cyclic deformation. Therefore, the superelastic-like behavior of the alloy after the cyclic deformation appeared in an isothermal tensile test at lower holding temperature.