超细晶粒WC—Co硬质合金的收缩与晶粒长大

采用复合烧结工艺（真空烧结＋热等静压烧结）制备超细晶粒ＷＣ－Ｃｏ硬质合金，研究了烧结过程中的超细合金的收缩及晶粒长大行为。结果表明，在常规的固相烧结阶段，局部微区内的液相烧结使超细晶粒ＷＣ－Ｃｏ硬质合金的收缩及晶粒长大行为不同于普通晶粒硬质合金。在此阶段，ＷＣ晶粒出现较严重的早期晶粒长大现象，导致合金的收缩占总体收缩量的９０％以上。

Shrinkage and Grain Growth of Ultrafine Grained WC Co Cemented Carbides

The combined sintering process (vacuum sintering plus HIP sintering) was introduced for producing ultrafine grained WC Co cemented carbides. The shrinkage and densification of the compacts during the combined sintering were studied. The results show that, the high selfdiffusion activities of W and C atoms enable them to quickly dissolve into the cobalt phase, for which the local liquid sintering takes place beforehand. The local liquid sintering is intimately correlated with the rapid shrinkage of the compacts and the substantial WC grain growth during the vacuum sintering stage (i.e.solid state sintering stage).