Small-Scale Insight into Uniform Deformability and Softening Resistance of Refractory High-Entropy Alloy

Owing to the outstanding softening resistance and thermal stability of BCC-structured refractory high-entropy alloys (HEAs), their unique deformation-induced defect structures merit investigation. Therefore, this study evaluated the mechanical properties and deformation behaviors of W-based low- to high-entropy alloys at various temperatures and orientations using nanoindentation and microcompression, complemented by post-mortem TEM and atomistic simulations to observe dislocation populations and their evolution. Results reveal that HEAs exhibit reduced elastic and plastic anisotropy while retaining high-temperature strength. With increasing compositional complexity, planar slip and abrupt stress drops were progressively replaced by homogeneous flow and smoother serrations. Severe lattice distortion promoted dislocation nucleation but impeded long-range glide, enabling cooperative edge and screw dislocation activity that sustained strength and work hardening across temperatures.