Effect of loading conditions and geometric factors on plasticity in complex concentrated alloys with various deformation mechanisms

CrMnFeCoNi quinary complex concentrated alloys (CCAs) exhibit excellent mechanical properties due to the complexity of their atomic environment, attracting significant attention as potential structural materials. However, to effectively utilized CCAs in structural applications, a comprehensive understanding of their plasticity under various loading conditions is imperative for CCAs with various deformation mechanisms. In this study, quinary CCAs were systematically designed to exhibit constant yield strength by controlling the electronegativity difference and tailoring deformation mechanisms through the Gibbs energy difference between γ-austenite and ε-martensite. Uniaxial tensile tests and limit dome height tests were conducted to evaluate plasticity under both uniaxial and biaxial loading conditions. The normalized strain and displacement values revealed a significant reduction in plasticity for TRIP and TADP CCAs under biaxial loading. To elucidate this phenomenon, we compared the maximum Schmid factors of dislocation glide and martensitic transformation for random orientations. As a result, from a geometrical perspective, TRIP is not effectively activated under biaxial loading condition. These findings offer novel insights into the role of the Schmid factor in plasticity of CCAs, focusing on the critical impact of loading conditions on martensitic transformation. Consequently, our results establish effective guidelines for designing CCAs with enhanced plasticity under various stress states.