A new model for nucleation in bulk metallic glasses

The nanostructured microstructures frequently obtained on crystallization of recently discovered easy metallic glass formers are generally believed to indicate a high nucleation rate and a slow growth velocity. This has been taken to signal either phase separation on an extremely fine scale in the undercooled liquid or glass prior to devitrification, or an extremely high density of impurity sites, favouring heterogeneous nucleation. Here, a model for homogeneous nucleation, which takes account of the linked fluxes of interface attachment and diffusion in the glass to the cluster neighbourhood, is proposed to explain these observations.