Nucleation and Growth of Voids in Quenched Aluminum

Abstract

The nucleation and growth process of voids in quenched aluminum has been studied by observing the changes in the stability of vacancy clusters with time and temperature. The nucleation is found to occur after quenching and to finish in a period very short as compared with the time required for the annihilation of quenched-in vacancies. The nucleation time is much shorter than that for dislocation loops. It is concluded that there exists a small definite size of the stable nucleus of a void. The cessation of the nucleation is performed by the retention of mobile vacancies in unstable vacancy clusters whose sizes are comparable to or larger than the void nucleus. The formation of dislocation loops and the escape of vacancies to pre-existing sinks are discussed in relation to the nucleation and growth of voids and dislocation loops. The annihilation process of vacancies during a slow quenching is interpreted in terms of the secondary defect formation.