Crystallization in Ni-Si-B glass: the influence of dispersoid additions

Abstract

Crystallization processes in an Ni-Si-B metallic glass have been examined both for the glass alone and for the glass containing a distribution of fine crystalline particles. In the absence of dispersoids, nucleation of crystals occurs uniformly throughout the glass volume on heating following an initial slow, transient period. Nucleation occurs preferentially at the glass-dispersoid interface for the particle-containing glasses. The rate of nucleation at the dispersoid-particle interface depends on the nature of the particle and can best be correlated with the degree of misfit between the substrate and nucleating crystal for the planes and orientation relationships considered. The rate of nucleation at the dispersoid surface is shown to be completely explained on the basis of the classical heterogeneous nucleation model. Nucleation in the bulk occurs many orders of magnitude faster than predicted by classical homogeneous nucleation: the implication of this on the interpretation of nucleation is discussed.