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 trans-formation 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.

Automated summary

In this study, Cu-Al-Ni based shape memory austenite single crystal with two different orientations was prepared for the first time via simple annealing cast alloy. The single crystal contains L21 matrix and rich-Fe nanoprecipitates with D03 and A2 structures. The martensitic transformation temperatures and chemical compositions of the two different-oriented single crystals are very similar. Both single crystals exhibit complete superelasticity when deformed from 3% to 8%. The critical stress for stress-induced martensite is about 500 MPa for the [2-75] single crystal, which is more than twice that of the [-401] single crystal. The [-401] single crystal shows better cycle stability, maintaining stable and perfect superelasticity over 500 cycles without fracture.