Local slip resistances in equal-molar MoNbTi multi-principal element alloy

SZ Xu and YQ Su and WR Jian and IJ Beyerlein, ACTA MATERIALIA, 202, 68-79 (2021).

DOI: 10.1016/j.actamat.2020.10.042

In this work, we calculate the local slip resistances (LSRs) in equal- molar MoNbTi multi-principal element alloy via molecular static simulations. We consider dislocations of either screw or edge character gliding on four types of slip planes, 110, 112, 123, and 134, in either forward or backward sense of the 111 slip direction. As references, we also compute the Peierls stresses of the same dislocations in two natural reference metals, Mo and Nb, and a synthetic one, the mean-field, A-atom potential-based MoNbTi. Further, we compare the LSRs with the corresponding ideal shear strengths that do not account for the lattice distortions induced by dislocation cores. We show that for neither dislocation character is the LSR on the 110 plane the lowest in MoNbTi, in contrast to Mo and Nb. For edge dislocations, slip on the 134 plane is the easiest, but for the screw dislocations, it is the hardest. For screw dislocations, the 112 glide plane is the most favored, while for edge dislocations, it is the least favored. We also find that the screw-to-edge ratio in the slip resistance is reduced by one order of magnitude in MoNbTi compared to that of any pure reference metal for the same type of slip plane. These results suggest that, in contrast to pure body-centered cubic (BCC) metals, BCC MPEAs could deform by a multiplicity of slip modes due to the lower screw-to-edge ratios and the lower LSRs for edge dislocations on the three higher order planes. (c) 2020 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Return to Publications page