Study of precipitates due to the addition of silicon in yttrium modified Ni–Al–Mo–B alloy IC6

The effect of adding 0.10–0.30 wt% Si on the microstructure of the yttrium modified alloy IC6 was examined by scanning electron microscopy (SEM). The chemical compositions of phases precipitated due to the presence of silicon were analyzed by the energy dispersive spectrum (EDS) technique of electron probe micro-analyser (EPMA). The crystal structures of precipitates were studied by transmission electron microscopy (TEM). The results show that two blocky-shaped phases, Mo1.24Ni0.76 and Mo6(Ni0.75Si0.25)7 are formed in the interdendritic area in the alloy with the addition of 0.10–0.20 wt% Si and 0.12 wt% Y, and that a needle-like phase named Y–NiMo precipitates in the interdendritic area in the alloy with addition of 0.30 wt% silicon and 0.12 wt% yttrium besides the formation of the blocky-shaped phases mentioned above.