Primary crystallization in (Fe, Ni)-based metallic glasses

Primary crystallization of a solid solution is studied for metallic glasses in the series (Fe100−xNix)100−yBy and (Fe100−xNix)93−yZr7By (at.%). The conditions under which the primary phase is bcc or ccp are characterized and then analysed in terms of homogeneous nucleation. The preference for the bcc phase is much stronger than expected from its thermodynamic stability and this is consistent with the primary phase selection in the solidification of binary Fe–Ni droplets. In each case the identification of the primary phase can be hindered by subsequent transformations, though these can be stifled in the finest crystallites and droplets.