Dislocation Multiplication from the Frank–Read Source in Atomic Models

Abstract

Dislocation multiplication from the Frank–Read source is investigated in aluminum by applying atomic models. To express the dislocation bow-out motion and dislocation loop formation, we introduce cylindrical holes as a strong pinning point to the dislocation-bowing segment. The critical configuration for dislocation bow-out in atomic models exhibits an oval shape, which agrees well with the results obtained by the line tension model. The critical shear stress for the dislocation bow-out in atomic models continuously increases with decreasing length L of the Frank–Read source (even at the nanometer scale). This is expressed by the function L⁻¹ ln L, which is obtained by a continuum model based on elasticity theory. The critical shear stresses for the Frank–Read source are compared with those for grain boundary dislocation sources, as well as the ideal shear strength.