Ultra-high toughness and ultra-high hardness WC-10Co-AlO cemented carbides were successfully prepared by vacuum liquid phase sintering (VS) and spark plasma sintering (SPS) using ultrafine WC and commercial Co powders as raw materials, respectively. The effects of nano-AlO content and sintering process on the relative density, average grain size, microstructure and mechanical properties of WC-10Co alloys were investigated. The results showed that the densification degree of the samples decreased with the increase of AlO content. In addition, the relative densities of the samples prepared by SPS were lower than those of the samples prepared by VS. For the samples prepared by VS, the average grain size increased first and then decreased as the AlO content increased from 3 wt% to 9 wt%, and the percentage of coarse grain showed the same trend. When the addition of AlO was 6 wt%, the average grain size reached the maximum value of 1.39 ± 1.03 μm. Meanwhile, the sample with 6 wt% AlO had a typical inhomogeneous dual-grain structure, and the percentages of fine grain (< 1 μm) and coarse grain (> 1 μm) were about 50%, which displayed the highest fracture toughness of 18.59 MPa·m. The dual-grain structure not only improved the toughness, but also compensated the loss of hardness. However, for the samples prepared by SPS, with the increase of AlO content, the average grain size of WC decreased, while both hardness and toughness were continuously improved. When the AlO content increased to 9 wt%, the grain size reached the minimum value of 0.25 ± 0.08 μm, and meanwhile, the hardness and toughness reached the maximum value of 19.69 GPa and 12.29 MPa·m, respectively. Moreover, as the AlO content increased, the transverse rupture strength (TRS) of the samples prepared by VS increased first and then decreased, and the TRS of sample with 3 wt% AlO reached the maximum value of 1410 MPa. However, the TRS of the sample prepared by SPS showed a decreasing trend.

中文翻译：

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烧结方法和Al2O3含量对WC-10Co硬质合金显微组织和力学性能的影响


以超细WC和商用Co粉为原料，分别采用真空液相烧结（VS）和放电等离子烧结（SPS）成功制备了超高韧性和超高硬度WC-10Co-Al2O硬质合金。研究了纳米Al2O含量和烧结工艺对WC-10Co合金相对密度、平均晶粒尺寸、显微组织和力学性能的影响。结果表明，随着Al2O含量的增加，样品的致密化程度降低。此外，SPS制备的样品的相对密度低于VS制备的样品。对于VS制备的样品，随着Al2O含量从3 wt%增加到9 wt%，平均晶粒尺寸先增大后减小，粗晶粒百分比也呈现出相同的趋势。当Al2O的添加量为6wt%时，平均晶粒尺寸达到最大值1.39±1.03μm。同时，Al2O含量为6 wt%的样品具有典型的不均匀双晶结构，细晶粒（< 1 μm）和粗晶粒（> 1 μm）的比例约为50%，表现出最高的断裂韧性18.59 MPa·m。双晶粒结构不仅提高了韧性，还补偿了硬度的损失。然而，对于SPS制备的样品，随着Al2O含量的增加，WC的平均晶粒尺寸减小，而硬度和韧性不断提高。当Al2O含量增加到9 wt%时，晶粒尺寸达到最小值0.25±0.08 μm，同时硬度和韧性分别达到最大值19.69 GPa和12.29 MPa·m。 此外，随着Al2O含量的增加，VS制备的样品的横向断裂强度（TRS）先增加后降低，其中Al2O含量为3 wt%的样品的TRS达到最大值1410 MPa。然而，SPS制备的样品的TRS却呈现下降趋势。