Room temperature dislocation loop dynamics in body-centered cubic refractory multi-principal element alloys

In this work, we study loop dynamics at room temperature across three refractory multi-principal element alloys (RMPEAs) using a phase field dislocation dynamics simulation method with Langevin dynamics. The analyses reveal two regimes in stress for all RMPEAs studied. In the low-stress regime, glide of the edge portions is smooth, and glide of the screw portions is jerky. In the high-stress regime, the edge to screw mobility ratio is approximately two and the edge mobility doubles from that in the low-stress regime. We also test a rapid density function theory-based method for generating energetic landscapes for large 3D crystals for simulation. As another key result, we find that dislocation mechanisms, velocities, and mobilities predicted between the two methods agree over a wide range of effective stresses, where the effective stress is the difference between the athermal lattice friction stress and the applied stress at 300 K. The second method is highly efficient, offering a way for performing dislocation dynamics quickly over a broad composition space.