Abstract Scope |
Refractory high entropy alloys (RHEA) are promising candidates as high-temperature structural materials due to an outstanding combination of strength, fracture toughness and creep resistance. However, while certain RHEA have been seen to retain strengths of over 500 MPa well above 1000C, the fundamental causes behind this display of high-temperature strength are still under active investigation. Here we present a theoretical and computational model based on the presence of atomic-level defects as the controlling elements of the alloy plastic response. The model solves the elastic/kinetic problem using dislocation dynamics within a kinetic Monte Carlo time evolution scheme, and captures the role played by screw and edge dislocations. We focus on one of the most popular quaternary systems, the equiatomic Nb-Mo-Ta-W alloy, described by suitable atomistic potentials, and from which we obtain all model parameters. Using the fully-parameterized model, we show very good agreement between model predictions and experimental yield-strength measurements |