Effects of cycling on the pseudoelastic properties of CuAlMnNi & TiNi based pseudoelastic alloys

Abstract

The deformation responses of a Cu-Al-Mn-Ni alloy and that of a commercially available Ti-Ni wire, both pseudoelastic at room temperature, have been studied under cyclic loading-unloading conditions at fixed maximum stress levels corresponding to strains of 5,4,3 and 2 % respectively in the case of Cu-Al-Mn-Ni alloy and at a maximum stress level corresponding to 7.5 % strain in the case of the Ti-Ni alloy wire and compared with results reported on pseudoelastic Cu-Al-Be alloys. The characteristics of the pseudoelastic stress-strain curves of the Cu-Al-Mn-Ni alloys which change their shape drastically on cycling are very different from that of the Ti-Ni alloy. The area enclosed by the stress strain curves denoting energy dissipation also decreases sharply in the initial cycles but both shape and magnitude of energy dissipation tend to stabilize somewhat as cycling proceeds. From the point of view of energy dissipation capacity and the number of cycles to failure Cu-Al-Mn-Ni alloys seem to perform much better than Cu-Al-Be alloys thus giving rise to the possibility that they are a better choice than Cu-Al-Be alloys for low temperature damping applications where Ti-Ni alloys may not be suitable. The performance of the Ti-Ni alloy wire in terms of energy dissipation capacity, stability of shape and endurance however is orders of magnitude superior to that of the Cu-Al-Mn-Ni alloy.