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In this study, the fatigue characteristics of additively-formed multi-principal element alloy (MPEA) of Co1.5CrFeNi1.5Ti0.5Mo0.1 (CoCrFeNiTiMo alloy) were systematically compared with conventional hot-rolled and additively-formed Alloy 718 nickel-based super alloy, which have comparable mechanical properties. Evaluated fatigue properties were the low- to high-cycle fatigue strengths of plane and notched specimens, and long / short fatigue crack growth (FCG) resistance. The results showed the fatigue strength of CoCrFeNiTiMo alloy to be comparable to that of Alloy 718 for smooth specimens, while the fatigue strength of notched specimens was 50% higher. Superior notch fatigue strength can be quantitatively explained in terms of outstanding long fatigue crack growth resistance. Regardless of load ratio, CoCrFeNiTiMo exhibits
superior FCG resistance that greatly surpasses that of conventional Fe and Ni alloys. In contrast, the short FCG resistance of CoCrFeNiTiMo was comparable to that of Alloy 718, which corresponds to the fatigue strength level of a smooth specimen. Investigation of fatigue fracture surface and microscopic slip deformation morphology around the fatigue crack indicates that CoCrFeNiTiMo alloy exhibits more planar slip
deformation than Alloy 718. Slip constraint stimulated by slip planarity appears to have an important role in short and long FCG resistance when cracks cross grain boundaries.

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• Creative Commons BY-NC-ND Attribution-NonCommercial-NoDerivs 4.0 International
  

  © 2023. This manuscript version is made available under the CC-BY-NC-ND 4.0 license https://creativecommons.org/licenses/by-nc-nd/4.0/.

Keyword: Fatigue, Additive manufacturing, High entropy alloy, Multi principal element alloy, Short fatigue crack

Date published: 2023-11-25

Publisher: Elsevier BV

Journal:

• MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING (ISSN: 18734936) vol. 891 p. 0-0

Funding:

Manuscript type: Author's version (Accepted manuscript)

MDR DOI: https://doi.org/10.48505/nims.4289

First published URL: https://doi.org/10.1016/j.msea.2023.145938

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Contact agent: Hideaki Nishikawa (National Institute of Materials Science (NIMS)) NISHIKAWA.Hideaki@nims.go.jp

Updated at: 2025-11-25 08:30:10 +0900

Published on MDR: 2025-11-25 08:21:41 +0900