Characterization of high-strength Ti–Ni shape memory alloys prepared by hot pressed sintering

Abstract High strength Ti–Ni shape memory alloy had been manufactured by hot-pressed sintering of Ti–Ni alloy powders. Due to the higher temperature sintering and assisted with the external pressure of 80 MPa, the higher density of Ti–Ni alloys can be obtained. The Ti–Ni alloy sintered at the appropriate sintering temperature was characterized by the network structure formed by the Ti2Ni phase distributing along the surface of original alloy powders. Merely one-stage B2⇌B19′ martensitic transformation was observed in the consolidated Ti–Ni alloy due to the homogeneous chemical composition, irrespective of the sintering temperature. The martensitic transformation temperature slightly changed, which was largely related to the number and distribution of Ti2Ni phase, as the sintering temperature increased. The mechanical properties of present Ti–Ni alloy were enhanced with the increased sintering temperature. Moreover, the outstanding strain recovery characteristics with the recoverable strain of 8.13% at the pre-strain of 10% condition can be achieved in Ti–Ni alloy prepared at the temperature of 1000 °C, which was attributed to the higher yield stress and weaker hamper effect of Ti2Ni phase on the movement of martensitic interface.