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

摘要

Phase stability and phase transformation were studied in the Fe-Co-Sb ternary system for the three sections: CoSb-Fe_(0.56)Sb_(0.44), 30 at. percent of Sb and 75 at. percent 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 X_(Fe)/(Z_(Fe) + X_(Co)). At 30 at. percent of Sb, the 68 and the bcc-A_2 phases are obtained across the whole Fe-Co section. On the CoSb_3 side (75 at. percent of Sb), Fe atoms cannot completely substitute for Co atoms in the skutterudite structure. Below 5 at. percent of substitution of Fe for Co in CoSb_3, only the D0_2 phase is present while for high concentration of Fe, marcasite and Sb phases coexist.