Enhancing fatigue resistance of Cr-Mn-Fe-Co-Ni multi-principal element alloys by varying stacking fault energy and sigma (�)-phase assisted grain-size reduction

Sisodia, S and Laplanche, G and Rajkowski, M and Chauhan, A (2025) Enhancing fatigue resistance of Cr-Mn-Fe-Co-Ni multi-principal element alloys by varying stacking fault energy and sigma (�)-phase assisted grain-size reduction. In: International Journal of Fatigue, 191 .

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Abstract

This study investigates two key aspects of the low cycle fatigue (LCF) behavior of alloys from the Cr-Mn-Fe-Co-Ni system at room temperature: (1) the influence of stacking fault energy (SFE) in single-phase face-centered cubic (FCC) alloys and (2) a grain size reduction triggered by the precipitation of a small amount of �-phase. The first effect is investigated using model alloys (Cr26Mn20Fe20Co20Ni14 and Cr14Mn20Fe20Co20Ni26 in at., grain size: �60 µm), which have distinct SFEs at room temperature. A reduction in SFE from 69 to 23 mJ/m2 results in a 10 to 20 increase in tensile/compressive peak stresses, i.e., cyclic strength, across all examined strain amplitudes (±0.3 , ±0.5 , and ±0.7 ) while maintaining comparable fatigue lives. Despite its higher cyclic strength, the low-SFE alloy exhibits delayed, and less evolved dislocation substructures than the other alloy. In both single-phase alloys, fatigue cracks originated from the surface reliefs, surface-exposed coherent annealing twin boundaries, and occasionally from high-angle grain boundaries. However, the crack propagation rate was slower in the low-SFE alloy, contributing to its superior fatigue resistance. By aging the low-SFE Cr26Mn20Fe20Co20Ni14 alloy differently, we could induce the precipitation of �5 �-phase during recrystallization, which strongly reduced the FCC grain size to �5 µm. With this microstructure, the cyclic strength increased by 50�65 and remained more stable during fatigue testing while maintaining a comparable life. The �-precipitates were found to deflect and arrest fatigue cracks, while extensive deformation twinning around cracks complements slip activity and reduces crack propagation rate. Overall, the �-phase-assisted grain size reduction is 3 to 5 times more effective in improving cyclic strength than SFE reduction. © 2024 Elsevier Ltd

Item Type:	Journal Article
Publication:	International Journal of Fatigue
Publisher:	Elsevier Ltd
Additional Information:	The copyright for this article belongs to Elsevier Ltd.
Keywords:	Cadmium alloys; Cobalt alloys; Die castings; Dislocations (crystals); Fatigue crack; Fatigue crack propagation; Fatigue damage; Fatigue testing; Grain size and shape; Iron alloys; Low-cycle fatigue; Manganese alloys; Mercury amalgams; Nickel alloys; Stacking faults; Superplasticity; Tensile strength; Tensile testing, Damage mechanism; Deformation and damages; Deformation mechanism; Fault energy; High entropy alloys; High-entropy alloy; Low cycle fatigues; Low-cycle fatigue; Microstructure design; Stackings, Grain boundaries
Department/Centre:	Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited:	12 Dec 2024 16:57
Last Modified:	12 Dec 2024 16:57
URI:	http://eprints.iisc.ac.in/id/eprint/87006

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