Dislocation multiplication from the FrankRead 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 FrankRead source (even at the nanometer scale). This is expressed by the function L ¹1 ln L, which is obtained by a continuum model based on elasticity theory. The critical shear stresses for the FrankRead source are compared with those for grain boundary dislocation sources, as well as the ideal shear strength.

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