Effect of powder particle size on gradient formation and grain growth in ultrafine crystalline gradient cemented carbide

•Ultrafine gradient cemented carbide was prepared by Sinter-HIP.•Effect of powder particle size on gradient formation in cemented carbide was studied.•Effect of powder particle size on grain growth in cemented carbide was studied.•The thickness of gradient layer increased with the decreasing of powder particle size.•EPMA was used to measure the distribution of elements in the gradient layer.

Sinter-HIP combining vacuum and pressure in one-step sintering process has been applied to prepare ultrafine crystalline cemented carbide with a surface gradient layer enriched in binder. The effect of powder particle size on gradient formation and grain growth has been examined. The results show that the gradient layer thickness increases with decreasing WC and Ti(C,N) powder particle size. The number of abnormal WC grains increases with decreasing WC powder particle size. The formational mechanism of the gradient cemented carbide with ultrafine grains is discussed through analyzing the decomposability of nanoscale Ti(C,N), atomic diffusion and grain growth during one-step Sinter-HIP process.