采用市售的粒度为0.8μm的WC粉末和粒度为1.6 μm的Co粉制备了WC-10％Co超细硬质合金,通过金相显微镜、扫描电子显微镜观察了不同烧结温度下制备的试样WC晶粒形貌,对超细晶粒硬质合金非均匀长大现象及机理进行了研究.结果表明:粉末湿磨后的粗大颗粒在烧结过程中起晶核作用,是引起晶粒非均匀长大的关键因素.固相烧结时,烧结体中细小颗粒受到张力的作用发生旋转,当其取向与邻近的大颗粒取向一致时,形成共格界面,以粗大晶粒为核心以并合的方式非均匀长大；液相烧结时,细小晶粒溶解并优先地在大晶粒的某些低能量晶面如(0001)和(1010)面析出,引起晶粒异常长大.本研究中,当烧结温度达到1410℃时,WC晶粒可异常长大为接近20μm的粗大晶粒.%The WC-10%Co ultrafine cemented carbide was prepared by commercialized WC powder with particle size of 0.8 μm and Co powder with particle size of 1.6 (Jim. The WC morphologies in the samples sintered at different temperature were observed by metallurgical microscope and scanning election microscope. Furthermore the abnormal grain growth in the ultrafine cemented carbide and its mechanism were researched. The results indicate that the coarse particles formed in wet milling act as seeds during sintering, which is the key factor causing abnormal grain growth. During solid phase sintering, the fine particles in the sintered body are rotated due to the tension, when the particle orientation is consistent with that of adjacent coarse particles, the coherent interface is formed, the coarse grains nucleate and merge, and the abnormal growth takes place. During liquid phase sintering, the fine particles dissolve and precipitate on certain low energy crystal face of coarse grain, such as (0001) and (1010), which results in abnormal grain growth. When sintered at 1 410 ℃, the WC grain can grow up to coarse grain with grain size of about 20 μm.
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