Effects of Mass Ratio of WC to Mo on Microstructure and Properties of TiC-based Cermets
TiC-based cermets were prepared with WC and Mo total mass fraction of 8％and mass ratios of WC to Mo of 1∶4,2∶3,3∶2,4∶1,and the effects of mass ratio of WC to Mo on the microstructure and properties of the samples were studied.The results show that the hard phases in the samples with different mass ratio of WC to Mo all had a core-ring structure.The core phase was mainly TiC,and the ring phase were mainly(Ti,M)C(M=Mo,W,V).When the mass ratio of WC to Mo was greater than 1,(Ti,M)C nanoparticles were in-situ precipitated in the binder phase.With the increase of the mass ratio of WC to Mo,the bending strength,fracture toughness and hardness of the samples increased first and then decreased,and the density increased.When the mass ratio of WC to Mo was 3:2,the comprehensive performance of TiC-based ceramics was the best,and the density was high,and the hardness,bending strength and fracture toughness were the largest,which were 1 546 HV,1 200 MPa,6.61 MPa·m1/2,respectively.When the mass ratio of WC to Mo was less than 1,the hard phase of the sample transgranularly fractured to form a cleavage section,and the binder phase was torn and deformed to form a rough section during bending.When the mass ratio of WC to Mo was greater than 1,the nanoparticle was pulled out from the binder phase to form a dimple.The larger the mass ratio of WC to Mo,the smaller the proportion of dimples on the fracture.
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