Kinetics of growth of spherical GP zones: experimental verification of the vacancy pump model

Abstract

The experimental verification of the “vacancy pump model” by X-ray small angle scattering is attempted on the Al-10% Zn and Al-10% Zn-0.1% Mg alloys. For the binary alloy the calculation of diffusion coefficients for the vacancy-zinc complexes and their initial number per unit volume gives values that cannot be explained by the existent data of activation energies. Without discussing the mechanism of the cyclic pump, a revision of the hypothesis that leads to the quantitative formulation of the model is suggested. For the ternary alloy, the possibility of a diffusion mechanism similar to that proposed for the binary alloy is admitted.