Effect of Aging Heat Treatment on Microstructure and Mechanical Properties of 50 wt.% Ni-42.5 wt.% Ti-7.5 wt.% Cu Shape Memory Alloy

NiTi alloys have good shape memory properties that adding alloying elements such as Cu can help to have smaller temperature hysteresis, better thermoelasticity, smaller superelastic hysteresis, higher damping capacity, and superior fatigue properties. The present work addresses functional mechanical properties of 50 wt.% Ni-42.5 wt.% Ti-7.5 wt.%. We study how aging heat treatment affects the alloy microstructure and mechanical properties. The results exhibit that increasing the aging temperature tend to increase the size of precipitation due to high diffusion in high temperature. The evaluation of mechanical properties reveals that the samples that aged in high temperature has lower fracture strength while these samples shows higher fracture strain. Aging time also has an effect on properties where by increasing the time, the size and amount of precipitations increase due to sufficient time for diffusion. By increasing the time, the fracture strength increase until a critical point and after that the fracture strength reduces.