Abstract Scope |
Refractory multi-principal element alloys (MPEAs) are promising candidates for structural applications demanding mechanical robustness at temperatures exceeding the capacity of state-of-the-art superalloys. While excellent high temperature strength has been demonstrated in many refractory MPEAs, a fundamental understanding of the nature of dislocation pathways in the BCC versions of these chemically complex alloys and their ability to enable macroscopic ductility is still in its infancy. We present a study of a ternary MPEA, MoNbTi, through a combination of in situ dislocation observations, microstructural investigations, and atomistic calculations. Our results highlight multi-planar, multi-character dislocation slip in MoNbTi at low homologous temperature, encouraged by the substantial dispersion in the glide resistance for dislocation due to the atomic-scale chemical fluctuations. The ability of dislocations to choose the easy gliding direction and plane enables an excellent combination of strength and homogeneous plasticity in this alloy, traits that are not simultaneously observed in conventional metallic alloys. |