Dislocation Multiplication from the Frank–Read Source in Atomic Models

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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 L11 lnL, 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. [doi:10.2320/matertrans.MA201319]