Microstructural evolution and mechanical properties of non-equiatomic (CoNi)CrFeC high-entropy alloy

(CoNi)CrFeC高エントロピー合金の微細組織変化と力学特性

Kim, Y. S.*; Chae, H.*; Huang, E.-W.*; Jain, J.*; Harjo, S.   ; 川崎 卓郎   ; Hong, S. I.*; Lee, S. Y.*

Kim, Y. S.*; Chae, H.*; Huang, E.-W.*; Jain, J.*; Harjo, S.; Kawasaki, Takuro; Hong, S. I.*; Lee, S. Y.*

In this study, we manufactured a non-equiatomic (CoNi)CrFeC high-entropy alloy (HEA) consisting of a single-phase face-centered-cubic structure. The non-equiatomic (CoNi)CrFeC HEA revealed a good combination of strength and ductility in mechanical properties compared to the equiatomic CoNiCrFe HEA, due to both stable solid solution and precipitation-strengthened effects. The non-equiatomic stoichiometry resulted in not only a lower electronegativity mismatch, indicating a more stable state of solid solution, but also a higher stacking fault energy (SFE, 50 mJ/m) due to the higher amount of Ni and the lower amount of Cr. This higher SFE led to a more active motion of dislocations relative to mechanical twinning, resulting in severe lattice distortion near the grain boundaries and dislocation entanglement near the twin boundaries.