Phase diagram of ternary Co-Fe-Ge system (I): Experimental

Co-Fe-Ge is an important material system for magnetic and catalyst applications. However, phase equilibria information of the Co-Fe-Ge ternary system is limited. Ternary Co-Fe-Ge alloys equilibrated at 950 degrees C were prepared. The microstructures, chemical compositions and crystal structure of each phase were determined. The phase equilibria isothermal section at 950 degrees C of the Co-Fe-Ge ternary system was then proposed. A continuous solid solution phase was formed between the Co5Ge3 and Fe5Ge3 phases and was labeled the beta(Co,Fe)5Ge3 phase. There are five three-phase regions in the system at 950 degrees C. A wide alpha 2 single-phase, and liquid phase regions with large composition ranges being confirmed at the Ge-poor and Ge-rich sides, respectively.