Role of aging time on the microstructure and shape memory properties of NiTiHfPd single crystals

Shape memory properties of [111] oriented NiTiHfPd single crystals aged at 600 °C for 48 and 72 h were investigated through isobaric thermal cycling and superelasticity experiments in compression. A maximum transformation strain of 2.6% at 1000 MPa compressive stress was attained above 100 °C. It was observed that precipitate size and interparticle distances were strong functions of aging time and subsequently govern the shape memory responses of the NiTiHfPd single crystals. Moreover, it was revealed that the elastic energy storage highly depends on precipitate characteristics.