A Discretized Peierls-Nabarro Model: Its Application to Peierls Stresses of Dislocations in a Variety of Crystals

Abstract

We have computed Peierls stresses of dislocations in a variety of crystals by applying a new discretized Peierls-Nabarro model (D-PN model) of the dislocation using the calculated ab-initio γ-surface. In the D-PN model, the disregistry distribution of atomic-row pairs facing at the glide plane is determined by the balance between the restoring stress due to the disregistry and the internal stress by an array of small dislocations placed at every intermediate position of atomic-row pairs, instead of continuous distribution of infinitesimal dislocations in the original PN model. Peierls stresses have been obtained by applying the shear stress to the model under which the structure is allowed to relax. The calculated Peierls stresses are largely reduced compared with those previously obtained by the original PN model (Y. Kamimura et al., Acta Mater. 148 (2018) 355-362), although the dislocation widths of the two models are almost the same. They have a good correlation with those experimentally estimated by Y. Kamimura et al. (Acta Mater. 61 (2013) 294-306) except for some very soft crystals, though the calculated Peierls stresses are generally still larger than those of experiments by a few factor.