Abstract The effect of ultrafine WC on the macroscopic shrinkage behavior and microstructural evolution of coarse-grained WC-Co cemented carbides during sintering was studied. WC-Co composite powders containing mixture of ultrafine (300 nm) and coarse (6.0 μm) WC powders were prepared using a novel sol-gel process. The results indicate that ultrafine WC addition enhanced shrinkage in the composite powder compacts during solid state sintering, while its influence on densification process in liquid-phase sintering can be ignored. The microstructural evolution confirmed that ultrafine WC addition promote the spreading of cobalt binder and the formation of WC-Co agglomerate in initial state of sintering. And, ultrafine WC addition resulted in a more uniform densification in the solid state sintering. Mechanisms of the enhanced shrinkage include the accelerated spreading of Co due to shortened diffusion distances and the increased surface diffusion velocity, and the activated sintering of WC skeleton due to grain boundary sliding.

中文翻译：

---

超细WC对粗晶WC-5Co硬质合金致密化行为和组织演变的影响

摘要 研究了超细WC对粗晶WC-Co硬质合金烧结过程中宏观收缩行为和微观组织演变的影响。WC-Co 复合粉末包含超细 (300 nm) 和粗 (6.0 μm) WC 粉末的混合物，使用新型溶胶-凝胶工艺制备。结果表明，超细WC的加入增加了复合粉末压坯在固相烧结过程中的收缩率，而其对液相烧结致密化过程的影响可以忽略不计。微观结构演变证实，超细WC的添加促进了钴粘合剂的扩散和烧结初始状态下WC-Co团聚体的形成。并且，超细WC的添加导致固态烧结中更均匀的致密化。