Densification behavior of ultrafine WC-based composites with AlxCoCrCuFeNi high-entropy alloy binders

Ultrafine WC-based cemented carbides with 10 wt.%Al_xCoCrCuFeNi high-entropy alloy (HEA) binders were fabricated by spark plasma sintering, and the effects of HEA binders on the densification behavior of the WC-HEA cemented carbides were studied. The densification of the WC-HEA cemented carbide, as well as traditional WC-Co, can be divided into the slow densification stage, rapid densification stage, and final densification stage. The densification behavior of the WC-HEA cemented carbides largely depends on the performance of the HEA binder during the SPS process. The sluggish diffusion effect of HEA weakens the diffusion of W atom on the powder particle surface and inhibits the growth of WC grain. Consequently, the disappearance of pores in the sintered compact is hindered, which leads to a low relative density of the WC-HEA cemented carbide. With the increase of Al content, the inhibitory effect of the Al_xCoCrCuFeNi binder on the growth of WC grain is suppressed, and an Al-containing phase with a low melting point is more likely to form. Therefore, the relative density of the WC-10 wt.%Al_xCoCrCuFeNi cemented carbide raises linearly with increasing Al content of the HEA binder.