纤维状WC晶粒硬质合金的制备

Fabrication of WC-Co alloy with fibrous WC grains

以高能球磨方法处理制备的纳米晶复合粉末为原料,通过真空烧结制备硬质合金块体,研究该纳米晶复合粉末的烧结致密化行为和显微结构特征。结果表明:该纳米晶粉末的烧结致密化可依烧结温度从低至高分为3个阶段,而在高于1 250℃的液相烧结阶段,将温度提高至1 375℃烧结30 min,可获得密度为14.46 g/cm3、烧结收缩率为27.2%的致密硬质合金。此时,WC晶粒呈纤维状,随机分布在烧结体中,其长度约为1.2μm,径向尺寸约为100 nm;采用高能球磨处理工艺可以获得原位生成的纤维状WC晶粒增强的硬质合金。

Nubbly WC-Co alloy was fabricated by using nano-grained W （Co, C） composite powders processed by high-energy ball milling as the raw materials, which was sintered in normal vacuum atmosphere. The sintering densification behavior of the nano-grained W （Co, C） composite powders and the characters of microstructure were investigated. As the results shown, three steps were appeared in the sintering process of nano-grained composite powder, in the third step i.e. the liquid phase sintering step, when sintered at 1 375 ℃ for 30 min the density and the ratio of sinter shrinkage of WC-Co alloy arrived 14.46 g/cm^3 and 27.2% respectively, and the fibrous WC grains about 100 nm in diameter and 1.2 μm in length were formed and distributed randomly in the sintered alloy, demonstrating the hard metal reinforced by fibrous WC grain would be achieved by high-energy ball milling process.