Dissolution of particles in binary alloys: part I. computer simulations

Abstract

A detailed numerical study has been made of the dissolution kinetics of particles in binary alloys during isothermal annealing. In earlier models, the assumption was made that the dissolution reaction could be described by the dissolution of only one particle in an infinite matrix or the dissolution of a regular array of particles of equal size. This assumption has been relaxed and a log-normal size distribution of particles has been introduced instead. The calculations have been done numerically by applying a finite difference technique to a spherical particle in a spherical cell of finite size. The presence of a size distribution of particles was found to have a great effect on the dissolution kinetics and, therefore, must be included in a reliable model for the dissolution of particles. The results have been presented in diagrams, giving the volume fraction as a function of the dimensionless annealing time with the geometrical standard deviation as a parameter, and thus should be useful in making accurate predictions of the dissolution kinetics of binary alloys. The curves can be used for all volume fractions provided that all of the particles can be dissolved completely at the temperature considered. Also, equations have been derived that can easily be used to give an estimate of the annealing time to dissolve 90 pct of the initial volume fraction.