Initial yield process around a spherical inclusion in single-crystalline aluminium

Abstract

The initial yield process and the subsequent formation of prismatic dislocation loops around a spherical inclusion embedded in a single-crystalline Al matrix are studied by atomistic simulations. In conjunction with linear elastic theory, it is confirmed that the maximum shear stress is created at the inclusion–matrix interface on the {1 1 1} plane intersecting the spherical inclusion at a height of (RP: radius of spherical inclusion). The critical pressure, shear stress and strain for dislocation nucleation are then quantitatively determined. Afterwards, prismatic dislocation loops, which are constructed by four pure edge dislocations with the same Burgers vector but not on the same slip planes, are formed by energetically unstable interactions around the inclusion. Consequently, analytical considerations and atomistic simulation provide a clear explanation of experimental observations and an instructive insight into the precipitation problem.