Insight into Grain Refinement Mechanisms of WC Cemented Carbide with Al0.5CoCrFeNiTi0.5 Binder.

Abstract

High-entropy alloys (HEA) as a kind of new binder for cemented carbide have garnered significant attention. In this work, WC/(17~25 wt.%)Al0.5CoCrFeNiTi0.5 cemented carbides were prepared by hot pressing sintering (HPS), and the reactions between WC powder and Al0.5CoCrFeNiTi0.5 powder during hot pressing sintering were elucidated. It found that different from traditional Co binder, the Al0.5CoCrFeNiTi0.5 binder effectively inhibited WC grain growth. During HPS, the decomposed W and C atoms from WC diffused into the Al0.5CoCrFeNiTi0.5 binder, reacted with the elements in the binder, and then formed the M(Co, Fe, Ni)3W3C phase. The back-diffusion of W and C atoms to WC grains was restricted by the Al0.5CoCrFeNiTi0.5 alloy and inhibited them from re-precipitating onto the large undissolved WC grains. As a result, the average size of WC grains in the cemented carbides was less than 200 nm. This work bright new insight into the grain refinement mechanisms of WC cemented carbide with HEA binder and provide a guidance for designing performance-stable WC/HEA cemented carbide and promoting their application.