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The solid solution strengthening and deformation mechanisms of HCP-MPEAs remain insufficiently understood due to the absence of alloys with stable single-phase HCP structures. In this study, single equiaxed HCP structures were successfully fabricated in Ti45Zr45Al10, Ti34Zr33Hf33, Ti35Zr30Hf30Al5, and Ti30Zr30Hf30Al10 alloys through the thermomechanical processing and subsequent heat treatment. The Ti45Zr45Al10, Ti30Zr30Hf30Al10, and Ti35Zr30Hf30Al5 alloys exhibit excellent 0.2 % proof strength from room temperature to 600 °C. The 0.2 % proof stress tends to increase with increasing mixing entropy and the average atomic radius misfit (δ), consistent with calculations showing that the solid solution strengthening effect increases with increasing the δ. Density functional theory (DFT) calculations further indicate that Al contributes significantly to this increase in solid solution strengthening. The deformation is dominated by (1010) prismatic slip. The low activation volume and high stress exponent of these alloys at 600 °C suggest minor obstacles such as cluster or short-range order inhibit the movement of dislocation and lead to significant solid-solution strengthening.

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• Creative Commons BY-NC Attribution-NonCommercial 4.0 International
  

Keyword: Hexagonal close-packed-multi-principal, Element alloys (HCP-MPEAs), Thermomechanical processing, Equiaxed HCP phase, High-temperature strength, Deformation mechanism

Date published: 2025-03-04

Publisher: Elsevier BV

Journal:

• Materials Science and Engineering: A (ISSN: 09215093) vol. 929 148143

Funding:

• Japan Society for the Promotion of Science 21H05198
• Light Metal Educational Foundation

Manuscript type: Author's version (Accepted manuscript)

MDR DOI: https://doi.org/10.48505/nims.5361

First published URL: https://doi.org/10.1016/j.msea.2025.148143

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Updated at: 2025-03-12 16:30:17 +0900

Published on MDR: 2025-03-12 16:30:19 +0900