Effect of Mixing Methods on Microstructure and Properties of Inhomogeneous Cemented Carbides
Inhomogeneous cemented carbides were prepared by using pre-sintered higher Co content fine-grained pellets(WC-12％Co)and lower Co content ultra-coarse-grained mixed powder(WC-8.5％Co)as raw materials with a mass ratio of 3∶7.The effects of different mixing methods on the microstructure and properties of the cemented carbides were studied by field emission scanning electron microscope,metallo-graphic microscope,coercive magnetometer,hardness tester,and electro-mechanical universal testing ma-chine.The results show that the cemented carbides mixed by dry mixing and dry milling exhibit an inho-mogeneous structure of coarse-grained WC surrounding aggregated fine-grained WC,while more Co pools are formed at the same time,deteriorating the properties of the cemented carbides.However,using high-strength wet milling method for mixing can reduce the probability of forming Co pools,promote the uni-form distribution of Co phase and WC grains,improve the density of cemented carbides,and achieve supe-rior comprehensive mechanical properties.In addition,the activity of WC grains in the pre-sintered fine-grained pellets is significantly reduced,which mitigates the effect of ball milling activation,slows down the growth rate of fine grains,and maintains the inhomogeneous structure of the wet-milled cemented car-bides.
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