| Abstract Scope |
In this work, we study dislocation behavior in body-centered cubic (bcc) refractory multi-principal element alloys (r-MPEAs), specifically MoNbTaW and MoNbTi, using atomistic simulations. Dislocation mobility is examined through molecular dynamics under varied stress and temperature conditions, revealing that local chemical inhomogeneity promotes kink nucleation, cross-kink formation, and edge dislocation pinning. To quantify slip resistance, we employ the nudged elastic band (NEB) method to calculate energy barriers for screw and edge dislocations on the {110}, {112}, and {123} planes. The energy barriers show strong dependence on local composition, with several slip systems exhibiting reduced barriers, suggesting the activation of multiple slip modes. Notably, the screw-to-edge slip barrier ratio is reduced by nearly an order of magnitude, indicating that edge dislocations play a more prominent role in plasticity than in pure bcc metals. These findings highlight how chemical complexity strongly influences slip behavior and shapes the deformation mechanisms in r-MPEAs. |