Kinetics of crystallization processes in glass forming melts

Abstract

A survey is given of experimental results concerning the kinetics of nucleation and the mechanism of crystal growth in glass forming systems. The main aim of the review is, however, to correlate the kinetics of overall crystallization processes in glass forming melts with structural changes taking place in the initial melt during crystallization. Detailed investigations of the kinetics of overall crystallization summarized here for a number of phosphate and silicate melts, indicate that even in relatively simple glass forming melts crystallization is in fact connected with considerable molecular (e.g. anionic) reconstructions. It is shown that the kinetics of nucleation in glass forming melts can be described in terms of the more general, transient formulation of the classical theory of phase formation. Experimental evidence on the mode of crystal growth in glass forming melts is summarized, attention being concentrated on data obtained at low undercoolings. The conditions for the predominant manifestation of the basic mechanisms of crystal growth (normal, spiral and via surface nucleation) are considered, accounting for the structure of the initial melts and the state of the crystal/melt interface.