WC-10％Co合金烧结过程中组织演变与矫顽磁力变化

摘要

利用矫顽磁力研究了两种不同WC粒度的WC-10％Co合金在烧结过程中组织演变.合金在1 200-1 450℃之间5个不同温度进行烧结,研究了不同温度下孔隙收缩、液相迁移、组织均匀化以及矫顽磁力变化.发现烧结过程中硬质合金组织分布经历了相对均匀到不均匀再到均匀的过程,与此同时合金的矫顽磁力经历了降低、升高再降低的过程,并且WC粒度越细的合金该现象越明显.实验结果表明合金组织越均匀其矫顽磁力越高.建立了优化的硬质合金矫顽磁力模型,模型表明硬质合金矫顽磁力由Co的磁畴以及WC/Co界面面积决定,而WC/Co界面面积受WC粒度和Co分布的影响.该模型可以很好的解释组织均匀性与矫顽磁力之间的联系.%The microstructure evolution during sintering of WC-10% Co alloy with two different WC particle average size was studied by coercive force test The alloy was sintered at five different temperatures from 1 200 to 1 450 X., then it was cooled down to room temperature. The shrinkage of pores, migration of liquid phase, homogenization of microstructure and coercive force under different sintering temperatures were studied. It is found that during sintering the microstructure of the cemented carbide undergoes a process from relatively homogeneous to unhomogeneous and then to homogeneous again, meanwhile the value of coercive force undergoes descent to ascent and then descent, which two phenomenons become more dramatic with the reduction of WC particle size. The results show that the more homogeneous the microstructure is the higher coercive force would be. An improved coercive force model is established, which can explain the relevance between coercive force and homogeneity of microstructure well. The model shows that the coercive force is determined by the original magnetic domain of cobalt and the area of WC/Co interface which is influenced by the WC particle size and the distribution of cobalLThis model can well explain the relationship between the microstructure homogeneity and coercive force.