Influence of vanadium carbides and stacking fault energy on the low-cycle fatigue behavior of a face-centered cubic multi-principal element alloy

Multi-principal element alloys (MPEA) have gathered significant attention in the scientific community due to their versatility and design concepts. The Fe30Mn10Co10Cr (at.-%) MPEA system revealed outstanding mechanical properties, owing to the activation of multiple strengthening mechanisms. In this MPEA system, the formation of vanadium carbides was found to be efficient to enhance the strength and to provide further design flexibility. However, the low-cycle fatigue behavior has not yet been investigated. To address this, a fully recrystallized, single-phase face-centered cubic (fcc) structure and a recrystallized and aged state that was strengthened by a uniform distribution of 6.5 % nanosized vanadium carbides were evaluated. It was revealed that the aged samples exhibited a notable improvement in cyclic fatigue performance. The precipitation of vanadium carbides led to a reduction in solute carbon content in the fcc matrix, which in turn resulted in the transformation-induced plasticity effect becoming the dominant deformation mechanism in the aged samples. This was coupled with a decrease in plastic strain amplitude and an increase in slip reversibility. As a result, the number of cycles to failure in the low-cycle fatigue regime increased by 40.8 % to 62.1 %, facilitating the concurrent optimization of both tensile and fatigue properties.