Latent heats of fusion and crystallization behaviors of Co–Si binary alloys

The latent heats of fusion ΔHms of Co–Si alloys over a wide range of composition have been determined. Based on the measured data, the dimensionless entropy (α = ΔHm/TlR, Tl is liquid temperature and R is gas constant) was calculated and the crystallization behaviors, faceted or non-faceted crystal growth, of several intermetallic compounds were predicted and examined by experiments. ΔHm increases with the Si content. However, the values are lower than those obtained via Neumman–Kopp rule with linear extrapolation. The α coefficients calculated by the experimental data reveal that the Co2Si, CoSi, and CoSi2, should grow in a non-faceted manner and it was proved by the microstructure observation after solidification. For α value determined by the Neumman–Kopp rule, Co–Si intermetallic compounds should be faceted morphology, indicating that their ΔHm should be measured experimentally.