Insight into Grain Refinement Mechanisms of WC Cemented Carbide with AlCoCrFeNiTi Binder.

High-entropy alloys (HEA) as a kind of new binder for cemented carbide have garnered significant attention. In this work, WC/(17~25 wt.%)AlCoCrFeNiTi cemented carbides were prepared by hot pressing sintering (HPS), and the reactions between WC powder and AlCoCrFeNiTi powder during hot pressing sintering were elucidated. It found that different from traditional Co binder, the AlCoCrFeNiTi binder effectively inhibited WC grain growth. During HPS, the decomposed W and C atoms from WC diffused into the AlCoCrFeNiTi binder, reacted with the elements in the binder, and then formed the M(Co, Fe, Ni)WC phase. The back-diffusion of W and C atoms to WC grains was restricted by the AlCoCrFeNiTi 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.