Influence of thermo-mechanical treatment on mechanical properties and shape memory effect of CuAlNiMnTi shape memory alloys

Shape memory alloys (SMAs) are vital in many advanced applications, such as micro-electro-mechanical systems (MEMS). Therefore, this work aimed at studying the effect of thermo-mechanical treatment in conjunction with alloying elements modification on improving the mechanical properties and shape memory effect (SME) of Cu-Al-Ni SMAs. In this study, the samples were divided into two groups: the first group was solution treated at 900 degrees C for 30 min. (S.T), and the other group was hot-rolled at 900 degrees C followed by solution treatment at 900 degrees C for 30 min. (H.R.S.T). The results showed that the hardness of the samples decreased with increasing the percent of Ni. In addition, the DSC investigations revealed that the martensite start temperature (Ms) decreased by 50-60 degrees C compared to the predicted Ms reported in the literature. Surprisingly, the alloying additions as well as thermo-mechanical treatment achieved a tensile elongation up to 22%, and a tensile fracture stress up to 600 MPa. Moreover, the shape recovery ratio exceeded 97%.