Effects of Mo Element on Microstructure and Mechanical Properties of CoCrFeMnNi High Entropy Alloys

In order to improve the mechanical properties of CoCrFeMnNi high entropy alloy, CoCrFeMnNiMox high entropy alloy were prepared by adding different content of Mo to re-alloying. The microstructure and phase composition were analyzed by OM, SEM, EDS and XRD, and the mechanical properties were tested by tensile test. The effects of Mo content on the phase composition and microstructure of CoCrFeMnNi high entropy alloy were investigated, and the mechanism of its influence on mechanical properties was studied. The results showed that with the increase of Mo element content, the crystalline morphology of CoCrFeMnNiMox high entropy alloy is change from dendrite crystals to cellular crystal, and the yield strength of the alloy is not change significantly. In the case of Mo content is less than 7%, Mo as substitutional atom is dissolves in the crystal structure of CoCrFeMnNi high entropy alloy substrate, which has function as solid solution strengthening, so that the strength of the alloy increases slightly, but the plasticity are not change significantly. In the case of Mo content is more than 7%, the ζ (CrMo) phase is precipitates in the alloy substrate, which has plays effect of second phase strengthening, so that strength of the alloy is increase significantly, and the plasticity is decreases obviously.