A comprehensive investigation of carbon micro-alloying on microstructure evolution and properties of metastable immiscible Cu-Fe alloy

In the present study, the effect of C micro-alloying on microstructure evolution and properties of metastable immiscible Cu-20Fe alloy was comprehensively investigated. Experimental results indicate that the microstructure of Cu-Fe alloy is extremely sensitive to the C content. It was found that obvious liquid-liquid phase separation (LLPS) behavior is observed in Cu-20Fe alloy after C micro-alloying, and the tendency of LLPS is enhanced with increasing C content. The calculation of ΔScc(0) suggests that C atoms preferentially pair with free Fe atoms to form new Fe (C) atomic clusters, thus resulting in the enhancement of bonding of the like-atom pairs. In addition, the quasi-binary phase diagram calculation further reveals the existence of a stable miscibility gap for C-containing alloys, and the temperature interval of miscibility gap is significantly enlarged with increasing C content. Meanwhile, the interface energy between two liquids formed by LLPS also slightly increases as C content increasing. These above reasons should be responsible for the microstructure evolution of Cu-20Fe-xC alloys. In addition, the C micro-alloying deteriorates the soft magnetic properties of Cu-Fe alloys to a certain extent, whereas improves its corresponding wear-resistance. • The microstructure evolution and solidification behavior of Cu-20Fe-xC alloys were clearly elucidated. • The calculation of ΔScc(0) indicates that C atoms preferentially pair with free Fe atoms to form new Fe(C) atomic cluster. • Phase calculation indicates that the metastable miscibility gap of Cu-20Fe alloy is stabilized by the introduction of C. • The addition of appropriate amount C enhances the wear-resistance of Cu-20Fe alloy.