Solidification Structure of Metastable Immiscible Cu-Fe Alloy Under Different Cooling Rates

The experimental Cu-10 wt% Fe alloy was prepared by high frequency induction melting and arc melting, respectively. The corresponding microstructure and phase structure of alloy were investigated. The results show that the microstructure of the alloy prepared by high frequency induction melting exhibited Fe-rich droplets and Fe-rich dendrites developed in the copper matrix, suggesting the occurrence of the normal liquid-solid transformation as well as the liquid-liquid phase separation during solidification. Meanwhile the Oswald ripening and coagulation of Fe-rich droplets were also observed in the sample. Moreover, the Fe-rich droplets mainly segregated at the center of sample due to the combined effect of Stokes motion and Marangoni migration. However, the solidification microstructure of the alloy obtained by arc melting presented cellular Fe-rich dendrites in the copper matrix. There was no evidence of the liquid-liquid phase separation. Instead, the alloy experienced liquid-solid transformation during solidification. In general, all the experimental alloy are found to display a crystalline structure of BCC epsilon-Cu and FCC alpha-Fe.