Effects of high-entropy alloy binders on the microstructure and mechanical/ thermal properties of cemented carbides

The binder phase performs critically on the comprehensive properties of cemented carbides, especially the hardness and fracture toughness relationship. There are strong motivations in both research community and industry for developing alternative binders to Co in cemented carbide system, due to the reasons such as price instability, property degeneration and toxicity. Herein, six kinds of high entropy alloys (HEA) including CoCrFeNiMn, CoCrFeMnAl, CoCrFeNiAl, CoCrNiMnAl, CoFeNiMnAl and CrFeNiMnAl were employed as the alternative binder for the preparation of WC-HEA cemented carbides through mechanical alloying and two-step spark plasma sintering. The impacts of HEA on the microstructures, mechanical properties and thermal conductivity of WC-HEA hardmetals were determined and discussed. WC-HEA hardmetals exhibited both superior hardness and fracture toughness to WC-Metal or WC-Intermetallic cemented carbides, indicating that HEA alloys were not only harder but also tougher in comparison with traditional metal or intermetallic binders. The HEA bonded hardmetals yielded thermal conductivities much lower than that of traditional WC-Co cemented carbide. The excellent HV-KIC relationship of WC-HEA facilitated the potential engineering structural application of cemented carbides.