烧结气氛对表面无立方相硬质合金组织和性能的影响

Effect of Sintering Atmosphere on the Microstructure and Properties of Cemented Carbide with Cubic-phase Free Layer

分别在氩气和氮气烧结气氛下制备了表面无立方相硬质合金,借助电子背散射衍射(EBSD)分析了表面无立方相层(Cubic-phaseFreeLayer,CFL)及相邻含立方相侧的组织特征,并对比了两种合金的切削性能。结果表明:在氮气气氛中烧结时,合金的液相维持时间更长,WC晶粒较氩气气氛烧结更为粗大。同时,氮气气氛下立方相的溶解析出被抑制,形成的CFL厚度较薄,立方相晶粒的聚集程度低于氩气气氛烧结,分布更加均匀。氮气气氛烧结的合金刀片在切削过程中可长时间维持刀尖形状,不发生软化变形,切削性能优于氩气气氛烧结的刀片。

Cemented carbides without cubic phase on the surface were prepared in argon and nitrogen sintering atmospheres,respectively.The microstructure characteristics of the Cubic-phase Free Layer(CFL)and its adjacent cubic-phase-containing side were analyzed by electron backscattering diffraction(EBSD),and the cutting properties of the two alloys were compared.The results show that:when sintered in nitrogen atmosphere,the liquid phase of the alloy lasts longer and the WC grains are coarser than those sintered in argon atmosphere.At the same time,the dissolution and precipitation of cubic phase in nitrogen atmosphere are inhibited,and the CFL formed is thinner,and the aggregation degree of cubic phase grains is lower than that of argon atmosphere sintering,and the distribution is more uniform.The alloy blade sintered in nitrogen atmosphere can maintain the tip shape for a long time without softening and deformation,and its cutting performance is better than that sintered in argon atmosphere.