Two-Way Shape Memory Effect Induced by Tension Training in Cu-13.4Al-4.0Ni (mass%) Alloy Single Crystals

Abstract

The two-way shape memory effect in CuAlNi shape memory alloy single crystals was studied. The effect was induced by cyclic tensile deformations of superelasticity and shape memory effect, and the efficiency of both methods was examined. Compared with the similar traininig process in the single crystals of CuZnAl alloys, the CuAlNi alloy showed much smaller changes in stress-strain behaviour and in the resulted two-way memory strain. The superelasticity training had no influence on both the stress-strain behaviour and the dilatation change. By shape memory training, the two-way memory strain increased to saturate at 0.90% after 10 cycles. Associated with this change, particular martensite variants increased its fraction and became “reproductive”. However, they were not the variants that were induced during the training, and further increase in the two-way memory strain was impossible by the formation of the observed variants. It was concluded that the present training methods were not effective for the two-way memory effect in CuAlNi shape memory alloy.