A model for the growth of solute clusters based on vacancy trapping

A simple model for the growth of clusters during the natural aging of Al alloys is presented. The model is based on the postulate that the attractive interaction between solutes and vacancies results in the trapping of vacancies at clusters. Assuming that the escape of vacancies from existing clusters is the rate-limiting step for cluster growth, the number of solute atoms in clusters is predicted to increase linearly with the logarithm of time, in agreement with several electrical resistivity results.