Mobility of lattice vacancies in iron

Abstract

Abstract Three series of experiments to measure the mobility of vacancies in iron have been performed with a high-voltage electron microscope. The temperature dependence of the growth speed of interstitial-type dislocation loops during electron irradiation between 400°C and 860°C indicates an energy of 0·62 ±0·07 eV, and this is assigned to one half of the migration activation energy of a single vacancy, namely 1·24·0·14 eV. The annihilation of electron–radiation–induced vacancies U detected by the shrinkage and disappearance of interstitial clusters during post–irradiation annealing at temperatures between 270°C and 350°C. The temperature dependence of the process yields the energy of 1–47 ± 0·05 eV. The extent of the annihilation of deformation-induced vacancies is detected by the variation of interstitial cluster formation by electron irradiation. This annihilation process gives the same energy, 1·50 ±0·08 eV, and the same annealing half–time as those in the annihilation process of the radiation–induce...