Void Nucleation Sites in Creep of Metals

Abstract

FOR metals undergoing slow deformation at elevated temperatures, it has been shown that nucleation of voids by condensation of lattice vacancies requires either a very high concentration of excess vacancies (approximately 100 times the equilibrium value¹), or very high concentration of stress². It appears that such concentrations of vacancies are never approached even at high rates of deformation³, so that voids must form at points where sufficiently large stresses develop. It has been suggested that ledges on a sliding grain boundary may provide these sites for nucleation.