Replacing Cobalt With a CoCrFeNiAl 0.3 High‐Entropy Alloy Binder in WC Cermets: Toward Enhanced Wear Resistance

ABSTRACT This study investigates the replacement of cobalt with a CoCrFeNiAl 0 . 3 high‐entropy alloy (HEA) binder in WC cermets fabricated via spark plasma sintering (SPS). Both WC–Co and WC–HEA cermets achieved near‐full densification, with relative densities of 99.78% and 99.84%, respectively. The WC–HEA composite exhibited a significant increase in hardness (1751 HV vs. 1346 HV, ∼30% higher) and demonstrated superior wear resistance after a 1000 m sliding test, with a mass loss of only 0.0041 g compared to 0.0147 g for WC–Co (over 70% reduction). Additionally, the WC–HEA cermet showed a lower and more stable coefficient of friction (average 0.4998 vs. 0.5446, ∼8% lower) and generated less oxide‐rich debris, indicating enhanced oxidation resistance during sliding. However, a moderate decrease in fracture toughness was observed (10.34 MPa·m½ for WC–HEA vs. 11.53 MPa·m½ for WC–Co). Microstructural analyses revealed that the HEA binder formed a multiphase structure containing W‐rich solid solution and Cr–Fe carbides, contributing to hardness and wear improvements. These findings demonstrate that HEA binders provide a promising alternative to conventional monolithic cobalt binders, offering superior tribological and mechanical performance, albeit with a trade‐off in toughness.