Analysis of the Clustering Process of Supersaturated Lattice Vacancies

Abstract

A method to perform a computer simulation of the step-wise reactions among vacancies up to large vacancy clusters is contrived to analyze the clustering process in an exhausting system as quenched-in vacancies. The variations of the progress of vacancy clustering with aging temperature and with the size of stable nucleus are investigated. Initial transient decrease of mobile vacancies with a rapid increase of small vancancy complexes establishes mutual quasi-equilibrium. Stationary stage of small vacancy complexes following the initial transient corresponds to the nucleation period of vacancy clustered defects. Factors which determine the size distribution of final clusters are discussed. Existence of a definite stable nucleus for a dislocation loop in aluminum is denied. Agreement of the computed results with experiment is obtained when small binding energies of a vacancy to vacancy clusters are postulated, i.e. , less than 0.2 eV up to the cluster of forty vacancies.