【摘要】 用真空热压法在 12 80～ 13 2 0℃温度范围内烧结制备了WC 0 .6VC 10Co超细硬质合金。微观组织结构和性能评价结果表明 :从国际市场上购买到的超细WC和Co粉 ,经过适当的粉末冶金工艺过程和 13 0 0℃以上压力辅助烧结可获得完全致密化的合金。致密化合金中的WC晶粒尚未明显生长 ,其平均晶粒间距为 169～ 179nm ,合金的维氏硬度值均超过了HV30 2 0 0 0 ;随烧结温度的升高 ,合金的Palmqvist断裂韧性增加 ,13 2 0℃热压样品的Palmqvist韧性值可达 5 17N·mm- 1 。在高分辨场发射扫描电镜下观察到的“WC晶粒团簇”现象 ,造成Co粘结相微观分布不均匀。对实验结果的分析和讨论有助于理解超细硬质合金烧结过程的机制和进一步优化其制备工艺过程。更多还原

【Abstract】 Ultrafine grained WC-0.6VC-10Co hard metals were made by mono-axial vacuum hot pressing (HP) between 1280～1320 ℃ which is around the eutectic temperature of the alloy. The results of evaluating the microstructure and the properties of the resulting hard metals show that fully densified alloys can be obtained when MVHP is carried out at temperatures≥1300 ℃ starting from commercially available ultrafine WC and cobalt powder. In the fully densified hard metals the grain size of WC is not increased. The average grain interception is between 169 and 179 nm and hardness values are over HV30 2000. The Palmqvist toughness (K c) of the hard metals increases with sintering temperature, and the highest value obtained is 517 N·mm -1 at 1320 ℃. The distribution of the Co binder is almost completely homogeneous at micro level but still inhomogeneous at submicron level. In order to improve further the toughness of the ultrafine WC-VC-10Co hard metals the optimization of the composition and the use of pressure-assisted liquid phase sintering, and optimization of the milling regime were discussed.更多还原