Temperature influence on deformation behavior of multi-principal element alloys (MPEAs) is a fundamental question yet to be well understood. In this work, we compare the low-cycle fatigue behavior of a CoCrFeMnNi MPEA at room-temperature (RT) and 550 °C [1-2].

The cyclic response of CoCrFeMnNi at 550 °C manifests minor cyclic softening, presence of serrated flow (with its magnitude decreasing with cycle number) and reduced fatigue life compared to that at RT. Microstructural investigations revealed that distinctly from the dominating wavy slip at RT, dislocations planar slip complements wavy slip at 550 °C, which explains well the temperature dependence of cyclic response. The unexpected planar slip at 550 °C is attributed to the increase of stacking fault width, likely due to Suzuki segregation.

This temperature dependence of CoCrFeMnNi’s behavior applies well to CoCrNi MPEA, albeit with much more pronounced planar slip, serrated flow and longer life of the latter [3]. Together, this work advances the understanding of temperature influence on LCF behavior of MPEAs.

References:

[1] K. Lu, A. Chauhan, D. Litvinov, J. Aktaa, Temperature-dependent cyclic deformation behavior of CoCrFeMnNi high-entropy alloy, International Journal of Fatigue 160 (2022) 106863.

[2] K. Lu, A. Chauhan, D. Litvinov, M. Walter, A.S. Tirunilai, J. Freudenberger, A. Kauffmann, M. Heilmaier, J. Aktaa, High-temperature low cycle fatigue behavior of an equiatomic CoCrFeMnNi high-entropy alloy, Materials Science and Engineering: A 791 (2020) 139781.

[3] K. Lu, F. Knöpfle, A. Chauhan, D. Litvinov, M. Schneider, G. Laplanche, J. Aktaa, Elevated-temperature cyclic deformation mechanisms of CoCrNi in comparison to CoCrFeMnNi, Scripta Materialia, 220 (2022) 114926.