| The ultrafine WC-14TiC-8Co powder doped VC,TaC or VC/TaC with an average particle size of 270nm was prepared by high-energy ball milling. The powder was cold isostatic pressed at 280MPa and vacuum sintered at 1380℃. The physical properties,transverse rupture strength(TRS),Rockwell hardness (HRA)and grain size of samples were detected.The results and inhibitory action mechanism were discussed.Finally,concluded as follows:1.The density,relative density,HRA and TRS of undoped alloy were 11.46g·cm-3,99.7%,91.8HRA,1220MPa respectively.With the increased of added quantity of VC,the density,TRS and Com of alloy decreased,while the HRA increased fist and then decreased.The Hc increased continually and increased quickly when added VC content between 0.6 wt.%and 1.0 wt.%.The optimum added quantity of VC was about 0.8 wt.%,the density,HRA,TRS and average grain size of alloy were 11.24 g·cm-3,91.8HRA,1220MPa,0.7μm respectively.2.With the increased of added quantity of TaC,the density and TRS of alloy decreased gently,while the HRA increased fist and then decreased.The TRS increased quickly when added TaC between 0 and 0.4wt.%and decreased gently when TaC content exceed 0.4wt.%.The Hc increased fist and then decreased which similar to the change of HRA,The Hc decreased quickly when added TaC between 0.6 wt.%and 0.8wt.%.The optimum added quantity of VC was about 0.6 wt.%,the density,HRA,TRS and average grain size of alloy were 11.43 g·cm-3,91.2HRA, 1390MPa,0.8μm respectively. 3.With the increased of added quantity of VC in the combined inhibitor,the HRA increased quickly fist and then decreased,and the maximal value reached 92.6 when added(0.4VC+0.4TaC)wt.%.The maximal value of TRS reached 1560MPa when added(0.3VC+0.5TaC)wt.%and decreased gently with the increased of added quantity of VC in the combined inhibitor.The Hc increased quickly fist and then decreased gently.The Com of samples which added VC/TaC were lower than undoped ones.The maximal value of Hc and Com reached 25.2kA·m-1,81.0%respectively when added(0.4VC+0.4TaC)wt.%.It indicated that carbon content and hard phase saturation ratio were normally.The optimum added quantity was(0.4VC+0.4TaC)wt.%,the density,HRA,TRS and average grain size of alloy were 11.26 g·cm-3,92.6HRA,1520MPa,0.6μm respectively.The density just decreased 0.2 g·cm-3,while the HRA heighten 2.4 and the TRS increased 280 MPa compared with undoped alloy.Alloy doped VC/TaC,the density decreased gently,but the HRA and TRS heighten evidently compared with that added VC or TaC individually.4.Used carbide of transition elements as inhibitor,whatever individual added or combined added would go against to densification process more or less,when added individually it would bad to TRS,while combined added the HRA and TRS would be improved because of grain refinement obviously.5.Grain size was controlled by inhibitor at different temperature ranges via dissimilar action mechanism;adsorption mechanism was the leading actor at solid sintering range;dissolution mechanism dominated at initial liquid sintering range; after that segregation mechanism controlled the process.The inhibitory action mechanism was an integration of adsorption mechanism,dissolution mechanism and segregation mechanism;combined added VC/TaC was an excellent association.
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