Crystal-melt interfacial free energies in metals: fcc versus bcc

The structural dependence of crystal-melt interfacial free energies (gamma) is investigated for fcc and bcc solids through molecular-dynamics calculations employing interatomic potentials for Fe. We compute approximate to30-35 % lower values of gamma for the bcc structure, and find that our results cannot be explained simply in terms of differences in latent heats (L) or densities (rho) for bulk bcc and fcc phases. We observe a strong structural dependence of the Turnbull coefficient alpha=gamma/Lrho(2/3), and find a trend towards lower crystalline anisotropies of gamma for the bcc structure relative to fcc.