Evolution of Microstructure and Mechanical Properties of the CoFeNiMnMox High-Entropy Alloys

In this study, the microstructure evolution and mechanical properties of CoFeNiMnMox high-entropy alloy after adding Mo were investigated. With the increase in Mo content, Mo atoms occupied lattice sites and the microstructure changed from hypoeutectic of primary FCC-phase to Laves phase particles of FCC-phase, and Vickers microhardness increased steadily from 193 to 357. The yield strength increased from 187 MPa when the Mo content was 0.25 to 537 MPa when the Mo content was 1.0. The microstructure formation can be explained by atomic size difference δ and parameter ΔχA. δ ≥ 3.87% and ΔχA ≥ 5.24% criterion is proposed to better predict the microstructure formation of the coexistence of (FCC + Laves) phases.