Effects of ternary additions on the microstructure and thermal stability of directionally-solidified MoSi sub(2)/Mo sub(5)Si sub(3) eutectic composites

Effects of ternary additions on the microstructure and thermal stability of directionally-solidified MoSi sub(2)/Mo sub(5)Si sub(3) eutectic composites have been studied for twelve different elements (Ti, V, Cr, Fe, Co, Ni, Nb, Ta, W, Ir, B and C) paying special attention to the variation of lattice misfits and interface segregation behavior with ternary additions. Among six elements (type-1: Ti, V, Cr, Nb, Ta and W) with a relatively high solubility in MoSi sub(2) and Mo sub(5)Si sub(3), Ta and W are found to be beneficial to microstructure refinement. All other six ternary elements (type-2: Fe, Co, Ni, Ir, B and C) with a negligibly low solubility in MoSi sub(2) and Mo sub(5)Si sub(3) exhibit a strong tendency to segregate on MoSi sub(2)/Mo sub(5)Si sub(3) interfaces, resulting in both microstructure refinement and the modification of the interface morphology.