Study on the Influence of Cu Content on Phase Transition Characteristics of Fe75Ni(25-x)Cu x Elastocaloric Refrigeration Alloys

Abstract

In this study, the mechanical alloying (AM) and powder metallurgy (PM) techniques were adopted to synthesize the Fe75 Ni(25-x) Cu x elastocaloric refrigeration alloys to research the effect of Cu contents on phase transition characteristics and microstructure of Fe75Ni(25-x) Cux elastocaloric refrigeration alloys. The conclusion was drawn that, with increasing Cu content, the phase transition characteristics changed and presented different changing trends. It was found that the phase enthalpy change value was 43.34J/g when the Cu content was 7at%, which was about 1.26 times of Fe15Ni (wt%) alloy. In addition, the FeNiCu alloy was a single-phase alloy with a crystal space group structure of Im-3m when the Cu content was 7at%, and the FeNiCu alloy was a two-phase alloy with crystal space group structures of Im-3m and Fm-3m when the Cu content was more than 7at%. This study provided an experimental basis for the theoretical investigation of the phase transition mechanism of FeNiCu elastocaloric refrigeration alloys.