Predicting Highly Anisotropic Dislocation Core Properties of B2 Alloys Using an Ab Initio-Informed Fully Discrete Peierls–Nabarro Model

An ab initio-informed fully discrete Peierls–Nabarro (FDPN) framework is employed to establish quantitative links among the generalized stacking fault energy (GSFE) landscape, dislocation core structure, and intrinsic lattice resistance in six B2 alloys (NiAl, FeAl, CoAl, RuAl, CoTi, and NiTi). Material-specific elastic constants and GSFE surfaces are used as direct inputs to the discrete dislocation model. The calculated core structures fall into compact and widely dissociated configurations, but the dissociation width is not uniquely determined by the antiphase-boundary (APB) energy, indicating that the full γ-surface topology and elastic anisotropy jointly regulate core spreading. The predicted Peierls stresses are 102.1 MPa for NiAl, compared with an experimental range of 20–30 MPa, and 1164.5 MPa for FeAl, approximately 9% lower than the reported value of 1281.74 MPa. The most pronounced anisotropy is found for CoTi: the predicted Peierls stress decreases from 2629.6 MPa for ⟨111⟩ slip to only 33.3 MPa for ⟨100⟩ slip. This nearly 80-fold contrast is consistent with the shallow ⟨100⟩ barrier (USF = 0.194 J/m2) and indicates that lattice resistance is governed by the complete direction-dependent GSFE landscape rather than by a single fault-energy descriptor. The results therefore establish a mechanistic route from γ-surface topology to core configuration and, ultimately, to anisotropic lattice resistance.