Mechanical behaviors of equiatomic and near-equiatomic face-centered-cubic phase high-entropy alloys probed using neutron diffraction

Wei, D.*; Gong, W.   ; Tsuru, Tomohito   ; Kawasaki, Takuro   ; Harjo, S.   ; Cai, B.*; Liaw, P. K.*; Kato, Hidemi*

In this study, we investigated the yielding and hardening behaviors of the Cantor alloy and FCC-phase Co-rich HEAs with different SFEs by in situ neutron diffraction combined with the first-principles method and electron-microscopy characterizations. The Co-rich HEAs exhibited a higher intrinsic yield strength than the Cantor alloy, mainly because of the larger shear modulus or modulus misfit, and grain refinement being more effective in improving the yield strength of low-SFE HEAs. Furthermore, higher flow stresses and better ductility of the Co-rich HEAs are attributed to the greater dislocation density and a larger number of stacking faults, which enhanced the strain-hardening rate during tensile deformation. The low SFE promoted mechanical twinning, and martensitic transformation contributed to higher strain-hardening rates.