The influence of particle shape on the non-isothermal kinetics of precipitate dissolution

Abstract

Based on the theory of precipitate dissolution kinetics proposed by Whelan, two expressions suitable for use under non-isothermal conditions were derived. The first one arises from the transient part of the diffusion field and it is found to be identical to that known as the three-dimensional diffusion kinetic law, being instead the reflection of a one-dimensional diffusion process. The second relationship which arises essentially from the steady-state part of the diffusion field, better describes a three-dimensional diffusion situation, being the corresponding kinetic model function in the integrated form: f( y)=1 -(1- y) 2 3 . The first solution was successfully applied for describing the dissolution behaviour of disc-shaped G.P. zones in 2219 aluminium under non-isothermal conditions, while the second was valid for description, under the same conditions, of the dissolution kinetics of spherical ordered domains in two αCuAl alloys.