Grain growth and Hall-Petch relationship in Ti37V15Nb22Hf23W3 refractory high-entropy alloys

摘要

Given the potential high-temperature applications of refractory high-entropy alloys (RHEAs), fully understanding the influence of heat treatment conditions on the microstructural evolution is very urgent. The effects of annealing on the mechanical characteristics of non-equiatomic Ti37V15Nb22Hf23W3 RHEAs that are 80% cold rolled are investigated in this study. Firstly, a single-phase body-centered cubic (BCC) solid solution is identified in both as cold-rolled and recrystallized states at 1000 degrees C, and the tensile strength decreases as the annealing time increases. Furthermore, the Hall-Petch relationship in the formula of sigma = 786 + 712D(-1/2) is shown to be effectively characterized the relationship between the grain size and yield strength. The friction stress of 786 MPa in Ti37V15Nb22Hf23W3 RHEAs is higher than that of most metals and alloys reported previously, indicating that the current BCC RHEA has a high intrinsic stress. The coefficient, 712 MPa mu m(0.5), is higher than that in the HfNbTaTiZr RHEA and lower than in the HfNbTiZr RHEA, indicating greater grain-boundary strengthening.

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