含板状WC晶粒硬质合金的强韧化机制研究

通过加入2.5%板状WC晶种,制备含板状WC晶粒硬质合金,研究其强韧化机制。结果表明:WC晶粒的各向异性和形状改变诱导的Hall-Petch硬化是硬质合金硬度增加的主要原因。加入板状晶种后,裂纹在扩展过程中出现了明显的穿晶断裂和Co相桥接,增加了裂纹偏转,硬质合金的抗弯强度大大提高。不同Co含量和初始WC粉体粒度制备的含板状WC晶粒硬质合金,穿晶断裂、Co相桥接和裂纹偏转对抗弯强度增加的贡献不同。

Study on the Hardening and Toughening Mechnisms of WC-Co Cemented Carbides with Plate-like WC Grains

WC-Co cemented carbides with plate-like WC grains were prepared by adding 2.5% plate-like WC seeds, and the hardening and toughening mechnisms were studied. The results indicate that Hall–Petch hardening of WC crystals induced by the anisotropy and plate-like shape is the main reason for the increase of the hardness. When added with plate-like WC seeds, the transverse rupture strength (TRS) of cemented carbides with plate-like WC grains is imporoved greatly, which is attributed to transgranular fracture of WC crystals, crack bridging of Co phases and crack deflection during crack propogation. The contribution of transgranular fracture of WC crystals, crack bridging of Co phases and crack deflection to the increase of TRS is different for WC-Co cemented carbides sintered by different Co contents and WC initial particle size.