In-situ Mo nanoparticles strengthened CoCrNi medium entropy alloy

Abstract

In present work, the CoCrNi/Mo mixed powder was designed and fabricated by a novel coating method followed by the calcination and reduction processes. The results indicated that in-situ Mo particles distributed homogeneous among the CoCrNi gas atomized powder and no other drawbacks generated such as contamination and oxidation, the reduced Mo particles were nanoscale, and maximum size did not exceed 600 nm. The SPSed CoCrNi/Mo composite with significant amount of in-situ μ phases showed improved mechanical properties: the yield strength and hardness from 352 MPa to 159 HV to 815 MPa and 375 HV, compared with the pure CoCrNi MEA (medium entropy alloy). The improved properties are mainly attributed to synergistic effects of various strengthening mechanisms, including solid solution strengthening, load transfer effect, Orowan strengthening, grain refinement, especially thermal mismatch mechanism. In addition, this could give insights on the applications of other MEA or HEA-based composites fabricated by coating method.