Elastic stresses in crystallization processes in finite domains

Abstract

Possible mechanisms of evolution and the effect of elastic stresses on crystallization processes of solid particles of finite size, in particular, on phase selection and the initiation of pore formation are studied. The subject area is of general relevance in the field of crystallization of amorphous materials, and more specifically in crystallization processes occurring in glass ceramics produced via the powder route. As a model, crystallization processes in finite spherical domains are analyzed. Two cases are considered here reflecting two possible scenarios of crystallization in particles of finite size: (i.) crystallization of the internal part of a finite domain and (ii.) crystallization from the boundaries. In order to account for the different types of response of the matrix to crystal formation, first, the computations are performed for the case that both the ambient and newly formed phases can be considered as Hookean elastic solids. In a second alternative approach, the effect of viscous relaxation of the matrix on the magnitude of the evolving stresses is estimated for the different situations analyzed. The results of the analysis are applied in an accompanying paper to stress induced pore formation and phase selection in a crystallizing stretched diopside glass, respectively, glass-forming melt.