Tuning interfacial wettability in high-entropy cemented carbides for enhanced mechanical performance

Abstract

This study investigated three newly developed high-entropy cemented carbides (HECCs) with high-entropy carbides (HECs) as the hard phase and Co as the binder. Accordingly, the interfacial wettability between HECs and Co was tuned by the changes in relative concentrations of the different metal components (e.g., W, Ta, and Ti) and C. Results demonstrate that the wettability between HECs and Co is dominated by the dissolution of HECs in Co, which determines the sintering behavior and hence the structure and performance of the materials. More specifically, the (W₆Ta₄Nb₁₀Zr₁₀Ti₂₀)C₅₀-Co with lower W content has poorer interfacial wettability, leading to pores in the sintered HECC. The (W₁₀Ta₁₀Nb₁₀Zr₁₀Ti₁₀)C₅₀-Co shows good interfacial wettability and strong resistance against grain boundary infiltration, owing to the formation of several atomic-layer-thick Co films between HEC grain boundaries. Reducing the C content facilitates the dissolution of HECs in Co, which can improve the interfacial wettability, but promotes the formation of η-W₃Co₃C phase and embrittle the material. The (W₁₀Ta₁₀Nb₁₀Zr₁₀Ti₁₀)C₅₀-Co with decent interfacial wettability exhibits a good balance of hardness (HV30 ∼1485), compressive strength (3316 MPa), and fracture toughness (10.9 MPa·m^1/2). The work demonstrates a design strategy achieving optimized microstructure and mechanical performance in HECCs via tuning interfacial wettability.