Study of Cu–Al–Ni–Ga as high-temperature shape memory alloys
The effect of Ga element on the microstructure, mechanical properties and shape memory effect of Cu–13.0Al–4.0Ni–xGa (wt%) high-temperature shape memory alloy was investigated by optical microscopy, SEM, XRD and compression test. The microstructure observation results showed that the Cu–13.0Al–4.0Ni–xGa (x = 0.5 and 1.0) alloys displayed dual-phase morphology which consisted of 18R martensite and (Al, Ga)Cu phase, and their grain size was about several hundred microns, smaller than that of Cu–13.0Al–4.0Ni alloy. The compression test results proved that the mechanical properties of Cu–13.0Al–4.0Ni–xGa alloys were improved by addition of Ga element owing to the grain refinement and solid solution strengthening, and the compressive fracture strains were 11.5% for x = 0.5 and 14.9% for x = 1.0, respectively. When the pre-strain was 8%, the shape memory effect of 4.2 and 4.6% were obtained for Cu–13.0Al–4.0Ni–0.5 Ga and Cu–13.0Al–4.0Ni–1.0 Ga alloys after being heated to 400 °C for 1 min.
The study was supported by the Natural Science Foundation of China (No. 51601126). The study was also supported by China Postdoctoral Science Foundation (No. 2016M601271).