The effect of nickel on the microstructure and property of Cu-Al-Nb shape memory alloys

In this study, alloys with a Cu-13.84Al-1.0Nb (wt. %) composition and different content of nickel (1.0, 2.0 and 3.0 wt%) were cast in a high frequency induction furnace, and reprocessed by the suction method for obtaining wires. The effect of Ni additions and the different cooling rates on the martensite stability and shape recovery were studied. It was observed that for alloys with a low nickel content the addition of Nb strongly influences the effect of tNi element by hindering the formation of the $\gamma_2$ (Al$_4$Cu$_9$) phase. ln alloys with a higher Ni content the XRD analysis clearly shows that the microstructure consists of 18R and 2H martensite