Orientation Dependence of Mechanical Properties in Single Crystal Cu-Al-Mn Superelastic Alloy

Cu-Al-Mn (CAM) shape memory alloys have been developed as next-generation SMAs after Ti-Ni SMAs because of their excellent workability [1]. Because of the recent progress to development of single-crystal manufacturing methods [2,3], applications to various fields, such as building materials, are expanding. Some issues remain to be addressed before the commercialization. For example, CAM has strong anisotropy in superelasticity, similar to other Cu-based shape memory alloys. In particular, the grain orientation dependence of the post-superelastic response is still hardly known. Since it plays a critical role in the design of seismic devices and elements, characterizing its grain orientation dependence is an essential issue toward its commercialization. In this study, the mechanical properties of single crystal samples with different crystal orientations were investigated from elasticity to rupture by tensile cycle tests. From the results, it can be concluded that mechanical properties as to grain orientation dependence of elasticity, superelasticity, and ductility can be roughly classified into three types. The single-crystal near <100> shows large elongation up to 90% as well as low Youngfs modulus and large superelastic strain [4]. This conclusion is important because it provides a whole overview of the orientation dependence of the mechanical properties in single-crystal CAM superelastic alloy. [1] R. Kainuma et al. Metall. Mater. Trans. A, 27A (1996), 2187. [2] T. Omori et al. Science, 341 (2013), 1500. [3] T. Kusama et al. Nature Comm., 8 (2017) #354. [4] S. Kise et al. J. Mater. Civ. Eng. 33(4) (2021) 04021027.