超细硬质合金晶粒生长抑制剂VC、Cr_3C_2作用机理的研究

本文以液相复合-连续还原碳化方法制备的掺杂有VC和Cr3C2抑制剂的纳米复合WC-10Co粉末为原料,采用真空烧结+低压处理的工艺制备超细WC-10Co硬质合金,运用原子力显微镜(AFM)和场发射扫描电镜(FESEM)确定VC和Cr3C2抑制剂在硬质合金中的分布,讨论其抑制晶粒生长的机理。一部分VC、Cr3C2抑制剂吸附在WC晶粒表面形成30nm～50nm的沉淀物,降低WC晶粒的表面能;一部分VC、Cr3C2溶解在Co相中,降低WC在液相中的溶解度;其余VC、Cr3C2沉积在WC晶界,从而有效地抑制WC晶粒的长大。

Research on the Inhibiting Mechanism of VC, Cr3C2 Codoped Ultrafine Cemented Carbide

In this paper, nanocrystalline WC-10Co composite powder produced by spray pyrogenation-continuous reduction and carburization technology was used to prepare ultrafine WC-10Co cemented carbide materials by vacuum sintering plus sinterhip, and the microstructure of sintered WC-10Co composites doped with VC and Cr3C2 is investigated by atomic force microscopy & field emission scanning electron microscope in order to locate the distribution of codoped elements in the ultrafine WC-10Co cemented carbide and understand the WC grain growth inhibiting mechanism. Some of the grain growth inhibitors VC, Cr3C2 adsorb on the surface of WC grains to form 30~50 nm precipitates, then low the surface energy of WC grain; some of inhibitors are soluble in liquid phase to low the solubility of WC phase in liquid phase; others precipitate along WC interfaces, a think layer of inhibitors compounds is frequently observed in random WC grain boundaries.