Effect of different rolling amount on the superelastic properties of Cu _70.8 Al _18.6 Mn _10.6 shape memory alloy

The objective of this study was to achieve high deformation plastic forming and obtain high comprehensive properties of the Cu-Al-Mn shape memory alloy (SMA) through the investigation of the effects of rolling with gradient deformation and subsequent heat treatment on the microstructure and mechanical properties of a columnar-grained structure Cu 70.8 Al 18.6 Mn 10.6 SMA. Subsequently, the wedge-shaped alloy samples were quenched after high temperature rolling at 800 and these samples were HR samples, and then the HR samples were heat treated at 800 for 1 h to obtain HR + HT samples. The findings indicate that the HR samples are capable of sustaining a columnar-grain structure even when subjected to high deformation. As the degree of rolling deformation increased, the Vickers hardness of the alloy exhibited a gradual enhancement, accompanied by a corresponding decline in the phase transformation temperature. The HR samples display excellent comprehensive mechanical properties, including high strength, superelasticity and a lower damping coefficient than that of HR + HT samples. The critical stress of martensitic transformation of the alloy increases significantly, from 109 to 276 MPa. In addition, the maximum superelastic strain ( ε SE Max ) of the gradient deformation samples can reach more than 8.5%. Furthermore, these samples can recover more than 90% strain after 12% loading strain. The damping coefficient is maintained at about 0.1. These enhanced properties are primarily attributable to a reduction in the transformation temperature and the formation of a deformed microstructure under conditions of high rolling deformation. The diameter of the recrystallised grains in the HR + HT samples decreased from a value exceeding 1 mm to a value of approximately 200 μm with an increase in rolling deformation. The transformation temperature of the HR + HT samples is higher than that of the HR samples and is essentially aligned with that of the as-cast alloy. The ε SE Max of HR + HT samples remain above 5%, and their damping coefficient is close to 0.1, indicating favorable comprehensive properties and reprocessing ability. This study not only offers a novel approach to the synthesis of Cu-Al-Mn SMA but also provides a theoretical and experimental foundation for the utilizations of this high-performance alloy.