Initial stage of fracture of aluminum with ideal and defect lattice

Abstract

In this work, we investigate the initiation of fracture in an aluminum sample with the help of molecular dynamics simulations. The critical negative pressures in different simulated regions as a function of the system size and initial structure are obtained. Tension in regions with defect structures, such as initial voids or dislocations and vacancies, leads to a decrease in tensile strength. In case of initial voids, a decrease in the ratio of the void radius to the system size causes an increase in the system's tensile strength, while rising temperature causes a linear drop of tensile strength. We propose a continuum dislocation based model of nanovoids growth to describe the critical negative pressure in systems with a void. Nucleation of dislocations near a growing void is taken into account with the Arrhenius-type law for the nucleation rate.