Superelasticity of different-orientated Cu–Al–Ni-based austenite single crystals

In this study, the Cu–Al–Ni based shape memory austenite single crystal (Cu-13.5Al–4Ni–6Fe–4Mn) with two different orientations were prepared for the first time through simply annealing cast alloy. The single crystal contains the L21 matrix and rich-Fe nanoprecipitates with two structures (D03 and A2). The martensitic transformation temperatures and chemical compositions of two different-oriented single crystals are very close. Two different-oriented single crystals both possess complete superelasticity when deforming from 3% to 8%. The critical stress of stress-induced martensite for the [2–75] single crystal is about 500 MPa, which is more than twice that of the [−401] single crystal. The [−401] single crystal has much better cycle stability, in which it can maintain stable and prefect superelasticity during 500 cycles without fracture.