Experimental determination of phase equilibrium in the Fe–Co–Sb ternary system

Phase stability and phase transformation were studied in the Fe–Co–Sb ternary system for the three sections: CoSb–Fe0.56Sb0.44, 30 at.% of Sb and 75 at.% of Sb. In the first section, we find a continuous solid solution without any secondary phase. The unit cell volume increases as a function of XFe/(XFe + XCo). At 30 at.% of Sb, the B8 and the bcc-A2 phases are obtained across the whole Fe–Co section. On the CoSb3 side (75 at.% of Sb), Fe atoms cannot completely substitute for Co atoms in the skutterudite structure. Below 5 at.% of substitution of Fe for Co in CoSb3, only the D02 phase is present while for high concentration of Fe, marcasite and Sb phases coexist.