Hot Workability of Cu-Zr Based Shape Memory Alloys for Potential High Temperature Applications

Since last years the development of high temperature shape memory alloys (HTSMAs) has been growing, thanks to the great interest in many industrial fields, such as automotive, aerospace, mechanical and control systems. Among the different SMA systems with high martensitic transformation temperatures, Cu-Zr based one can be an interesting candidate. For these reasons, the goal of this work is the study of hot workability of some Cu-Zr based shape memory alloys. In particular, this study addresses on the effect of hot rolling process on the metallurgical and calorimetric properties of ternary and quaternary Cu-Zr based SMAs. The addition of some alloying elements (Cr, Co, Ni…) is taken into account and their effect is also put in comparison with the binary system. The alloys were produced by means of an arc melting furnace in inert atmosphere under the shape of cigars. Due to the high reactivity of these alloys at high temperature, the cigars were sealed in a stainless steel can before the processing and two different procedures of hot rolling were tested. The characterization of the rolled alloys is performed using discrete scanning calorimetry in terms of evolution of the martensitic transformation. The analysis is completed with mechanical and the microstructural investigations by means of microhardness and scanning electron microscopy, respectively. Moreover, thermo-mechanical characterization was also proposed for evaluating the mechanical response of the rolled alloys.