Abstract Scope |
In this study, a series of (CoCrNi)100-x-yTixMoy medium entropy alloys (MEAs) was processed using arc melting to improve the mechanical properties of CoCrNi MEA. The results showed that the addition of Ti and/or Mo led to enhanced strength but lower ductility due to solid solution strengthening, grain boundary strengthening and precipitation strengthening. Additions of Ti and Mo in FCC CoCrNi matrix would prompt the formation of HCP Ni3Ti and σ Cr-Mo rich precipitates, respectively. The nanohardness of FCC matrix, HCP and σ precipitates were approximately 6, 9 and 12 GPa, respectively. However, compared to Mo addition, Ti addition showed a more prominent strength-ductility trade-off for CoCrNi-based MEAs. The optimum mechanical properties of yield strength, ultimate tensile strength, fracture elongation, and microhardness of 953.70 MPa, 1319.09 MPa, 22.09%, and 424 HV, respectively, were obtained in (CoCrNi)94Ti3Mo3 MEA compared to 417.74 MPa, 813.14 MPa, 63.13%, and 226.6 HV in CoCrNi MEA. |