Microstructure, superelasticity and shape memory effect by stress-induced martensite stabilization in Cu–Al–Mn–Ti shape memory alloys

Abstract

In this study, the microstructure, martensitic transformation, superelasticity, stabilization of stress-induce martensite and the corresponding shape memory effect of Ti-doped Cu–Al–Mn shape memory alloys were investigated. The results show that the present Cu–Al–Mn–Ti alloys consist of two types of L21 phases, including Cu2AlMn parent and Cu2TiAl precipitate. The dispersive L21–Cu2TiAl precipitates strengthen the stabilization of stress-induced 2H(γ′1) martensite from L21–Cu2AlMn parent. Thus, all studied alloys show not only superelasticity at deformation, but also shape memory effect after unloading by heating. Consequently, the Cu–12.9Al–8.3Mn–0.5Ti alloy (wt%) possesses the best superelastic strain up to 4.6% and a shape memory effect of 1.5% under a pre-deformation of 11%, while Cu–12.8Al–7.7Mn–2.6Ti alloy (wt%) shows the best shape memory effect up to 2.5% simultaneously showing 1.9% of superelastic strain with a pre-deformation of 10%.