Effect of Mo Content on Microstructure and Mechanical Properties of Cocrfeni Series High-Entropy Alloys

Abstract

In this paper, the microstructure and mechanical properties of CoCrFeNiMox (x=0, 0.1, 0.3, 0.5, 0.7, and 1.0) high-entropy alloys (HEAs) prepared with vacuum arc melting method are studied in detail. After Mo-doping, the strengthening mechanisms of HEAs mainly include the enrichment of components strengthening and the second-phase particles strengthening. The Cr and Mo elements are enriched at the grain boundary of HEAs, which leads to the formation of σ phase and strengthens the alloys. From the results of mechanical properties, the microhardness and strength increase with Mo contents, while the percentage elongation decreases gradually. Among which, the higher microhardness, yield strength, and ultimate tensile strength of CoCrFeNiMo0.3 alloy reach 205.96 HV, 333.43 MPa, and 671.02 MPa, respectively, compared with other alloys. More importantly, the percentage elongation of which remains 32%, and the microhardness distribution is uniform with an average value of 7.40 GPa and an elastic modulus of 263.6 GPa. The research findings presented in this paper can serve as a valuable theoretical basis and practical foundations for the strengthening efforts of face-centered cubic HEAs.

Keywords: High-entropy alloys (HEAs), Microstructure, Mechanical properties, second phase strengthening, nanoindentation hardness