An assessment of isothermal crystallization kinetics in glass by mathematical modeling

A mathematical model is presented to assess the devitrification kinetics of glasses-under isothermal conditions. The model takes into account all the experimentally observable aspects of nucleation and growth behavior. A part icle size distribution function is defined from the nucleation and growth p arameters, and used to calculate the transformed volume fraction, the numbe r of crystals and their mean and maximum radii according to the isothermal heat treatment time. The model was validated with a barium disilicate glass that crystallizes uniformly and rapidly into spherical particles; the nucl eation and growth curves were therefore determined for BaSi2O5 crystals. Th e simulated and experimental results are compared and discussed. The model closely approximates the actual results, and can describe the devitrificati on kinetics of any glass matrix for which the nucleation and growth mechani sms have been defined. (C) 2001 Published by Elsevier Science B.V.