Drastic oscillation of peierls stress from peierls-nabarro model calculation and its remedy

Peierls stress (Tp) of face-centered-cubic (FCC) structures from the Peierls-Nabarro (PN) model calculation is extremely sensitive to the input parameters including the shear modulus (m), Poisson's ratio (n) and generalized stacking fault energy (GSFE), which makes the model not a very reliable tool for the prediction of Tp because uncertainties occur inevitably in the theoretical calculation or experimental measurements of these input parameters. In the present work, we scrutinized systematically the sensitivity of Tps of the FCC metals to the input parameters within the framework of semi-discrete variational PN (SVPN) model. We showed that Tp oscillates drastically with varying input parameters. The period of the oscillation is associated with the dependence of the distance between the two partials of the extended dislocation (D) on m, n and GSFE while the amplitude of the oscil-lation is modulated by the dependence of the half-width of the partial dislocation (z) on these input parameters. Based on the explored origin of the oscillation, a modified SVPN model is proposed to relieve the sensitivity of Tp on the input parameters. The Peierls stresses evaluated with the modified SVPN model are in general agreement with the available experimental values for all the FCC metals.(c) 2023 Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

The Peierls stress of FCC structures calculated using the PN model is highly sensitive to various input parameters, such as shear modulus, Poisson's ratio, and generalized stacking fault energy. This sensitivity leads to significant oscillations in the predicted Peierls stress. In this study, we propose a modified model that alleviates the sensitivity of the Peierls stress on the input parameters, resulting in better agreement with experimental values.