Effect of AlCoCrFeNiTi high entropy bonding phase with different content on properties and microstructure of WC cemented carbide

Abstract

This study systematically investigated the effects of AlCoCrFeNiTi high-entropy alloys with different contents (5–30 wt%) as binder phases on the microstructure and mechanical properties of WC cemented carbides. The results showed that the high-entropy binder phase significantly inhibited the growth of WC grains through the high-entropy effect. Among them, WC-10AlCoCrFeNiTi exhibited the optimal comprehensive performance, with an average grain size of 0.308 μm, which was 36.9 % smaller than that of traditional WC-10Co (0.488 μm). Its hardness reached 1889.5HV (1700HV for WC-10Co), and the fracture toughness was 12.69 MPa m^1/2 (8.9 MPa m^1/2 for WC-10Co). However, the insufficient wettability of the high-entropy binder phase led to lower relative density and bending strength of WC-5AlCoCrFeNiTi–WC-30AlCoCrFeNiTi alloys compared with WC-10Co. When the content of the high-entropy binder phase increased to 30 wt%, the grains abnormally grew to 0.473 μm, but the relative density of the alloy increased to 96 %, and the fracture toughness anomalously increased to 13.7 MPa m^1/2, which was attributed to the synergistic effect of the crack deflection effect of coarse grains and high density. The fracture morphology indicated that the increase in high-entropy content promoted the transformation of the fracture mechanism from brittle fracture to ductile fracture.