Effective and back stresses evolution upon cycling a high-entropy alloy

Abstract

We report on the effective and back stresses evolution of a CoCrFeMnNi high-entropy alloy (HEA) by partitioning its cyclic hysteresis loops. It was found that the cyclic stress response of the HEA predominantly originates from the back stress evolution. Back stress also increases significantly with increasing strain amplitude and reducing grain size. However, the change of effective stress is rather insignificant with altering cycle number, strain amplitude and grain size. This indicates that the effective stress is determined mainly by the lattice friction. Further comparisons to an austenitic steel and a medium-entropy alloy identified the origins of their peculiar cyclic strength.

GRAPHICAL ABSTRACT

IMPACT STATEMENT

The effective stress and back stress upon cycling a HEA are assessed, both of which are higher than a conventional FCC steel, contributing to the HEA’s higher cyclic strength.

KEYWORDS:

• High-entropy alloy
• fatigue
• effective stress
• back stress

Acknowledgements

The authors acknowledge Prof. Dr. M. Heilmaier, Dr. A. Kauffmann, and Dr. A. S. Tirunilai for providing the CoCrFeMnNi, Prof. Dr. G. Laplanche and Dr. M. Schneider for providing the CoCrNi, as well as Prof. Dr. J. Freudenberger for performing rotary-swaging. K. L. thanks Dr. D. Litvinov and Dr. M. Walter for their kind guidance in using the TEM and the fatigue testing machine. We also acknowledge support by the KIT-Publication Fund of the Karlsruhe Institute of Technology.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Correction Statement

This article has been corrected with minor changes. These changes do not impact the academic content of the article.