Sympathetic nucleation: an overview

Sympathetic nucleation is defined as the nucleation of a precipitate crystal at an interphase boundary of a crystal of the same phase when these crystals differ in composition from their matrix phase throughout the transformation process. Following a brief history of the discovery and interpretation of this phenomenon, the means of identifying the presence of sympathetic nucleation are described. The morphological configurations most frequently produced by sympathetic nucleation are illustrated. Heterogeneous nucleation theory is then applied to explain sympathetic nucleation. Particular emphasis is placed upon the driving force for sympathetic nucleation, since many of the effects of phase diagram geometry and supersaturation upon sympathetic nucleation can be simply explained upon this basis.