Growth of Interstitial Type Dislocation Loops and Vacancy Mobility in Electron Irradiated Metals

Abstract

Interstitial type dislocation loops formed in Al, Au, Cu, Fe and Mo by electron irradiation in a high voltage electron microscope grow proportionally to a smaller power of the irradiation time than unity at lower temperatures under constant irradiation. They grow linearly with the irradiation time at higher temperatures at which vacancies are mobile. The balance of the product of the mobility and concentration between interstitials and vacancies explains the linear growth as well as the observed square root dependence of the growth speed on the irradiation intensity. The temperature dependence of the growth speed can be used to obtain the migration activation energy of vacancies. Temperature independent growth in a very thin specimen is understood as the surface dominant case as sinks. Sink efficiency of an edge dislocation to interstitials and vacancies is discussed.