Numerical simulations of the relaxation effect on crystal nucleation in supercooled glass-forming liquids and glasses

Abstract

This project is focused on detailed numerical simulations of the effect of step-wise relaxation process on the nucleation of crystalline phases in glass or a supercooled glass-forming liquid. The parameters of the relaxation and crystallization processes - number and duration of relaxation steps, the distribution function of the number of crystals per unit volume, N(t) curves, partial steady-state nucleation rates - will be simulated and compared with experimental data for crystallization of a lithium disilicate glass (Li2O*2SiO2) at very low nucleation temperatures, Tn=663K, 683K and 693K, that is 61K, 41K and 31K below T12, which are currently being performed at the Vitreous Materials Lab - Dept. Materials Engineering, Federal University of São Carlos.We anticipate that this research work might result in the following findings:(i) Parameters of the crystallization processes: the distribution function of nuclei, N\(t\)-curves, partial steady-state nucleation rates at different steps. Simultaneous experimental work may provide a solid basis to check the validity of the simulations.(ii) A useful approximate model for determination of the time dependence of structural order parameter will be developed for low nucleation temperatures (Tn<730K) when the effect of stepwise structural relaxation must be taken into account.These expected new findings are of great scientific significance to shed light on the theory of nucleation, and might also have some technological importance for glass-ceramic development and sinter-crystallization processes. (AU)