Yield strength anomalies (YSAs) in L1 2 intermetallics are commonly interpreted using the Paidar–Pope–Vitek (PPV) model, which attributes the anomaly to an elasticity-based description of the screw dislocation core structure during cross-slip. However, this picture remains incomplete, as predicted cross-slip driving forces and energy barriers do not consistently rationalise trends across chemistries. Here, we present a first-principles investigation of screw dislocation core structures in ten L1 2 compounds with varying temperature-dependent yield strengths. Ground-state and quasistatic finite-temperature γ -surfaces are incorporated into semi-discrete variational Peierls–Nabarro simulations to obtain core structures on the primary 111 glide plane prior to cross-slip. The local stabilities of the complex intrinsic stacking fault (CISF) and antiphase boundary (APB) govern both core structure and anomaly strength. Unstable CISFs and low APB stabilities yield compact, overlapping superpartial cores and strong anomalies, whereas stable faults promote fully dissociated fourfold cores and weaker anomalies. Temperature reduces planar fault energies and may facilitate cross-slip through core modification. Analysis of antisite energetics, charge redistribution, and magnetic effects indicates that unfavourable B–B bonding dominates CISF energetics, with secondary electronic and magnetic contributions. These results establish a direct link between γ -surface topology, dislocation core structure, and anomalous yielding in L1 2 intermetallics.
Zelin et al. (Fri,) studied this question.