VC and Cr₃C₂ grain growth inhibitors (GGIs) and WC ultrafine cemented carbides were synthesized in-situ by spark plasma sintering (SPS) with W, C, Co, V, and Cr as raw materials. The effects of sintering parameters and difference in the particle size (50/500 nm) of raw materials on the microstructure and performance of the alloys were evaluated. The hardness and toughness of the specimens prepared by sintering the raw material particles with equivalent spherical diameter of 500 nm and additive content of 1.2 wt.% at 1350°C and 35 MPa for 8 min were 1889.90 kgf/mm² and K_IC 9.98 MPa·m^1/2, respectively. The results showed that the specimen has high hardness and toughness (2059.10 kgf/mm², K_IC 14.06 MPa·m^1/2) prepared at 1400 ℃ for 8 min under a pressure of 35 MPa with the raw material particles having an equivalent spherical diameter of 50 nm, and an additive content of 0.8 wt.%. With similar sintering parameters, reducing the particle size of the raw powders (500 to 50 nm) could effectively enhance the mechanical properties of the specimens，the Vickers hardness and density increased by 8.96% and 4.37%, respectively, and the fracture toughness is significantly improved by 40.88%. Both large and small grains are present in the sample, the small-size grains provide the sample with better hardness and the large-size grains endow the sample with excellent toughness. The preparation of ultrafine cemented carbide by in-situ synthesis is feasible, but it is susceptible to uneven grain size distribution and more defects. This can be solved by reducing the raw particle size and optimizing the sintering process appropriately. This study provides a feasible way for the in-situ preparation of high strength and toughness cemented carbides.

中文翻译：

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放电等离子烧结的原位制备及其性能


以W、C、Co、V和Cr为原料，采用放电等离子烧结（SPS）原位合成了VC和Cr ₃ C ₂ 晶粒生长抑制剂（GGIs）和WC超细硬质合金。评价了烧结参数和原材料粒度差异 （50/500nm） 对合金微观组织和性能的影响。将等效球形直径为500nm、添加剂含量为1.2wt.%的原料颗粒在1350°C、35MPa下烧结8min制备的试样的硬度和韧性分别为1889.90kgf/mm ² 和K _IC 9.98MPa·m ^1/2 。结果表明，在1400 °C、35MPa压力下制备了8min的试样，原料颗粒等效球形直径为50nm，添加剂含量为0.8wt.m，制备了高硬度和韧性（2059.10kgf/mm，K ² _IC 14.06MPa·m ^1/2 ）。在相似的烧结参数下，减小原料粉末的粒径（500 至 50nm）可以有效提高试样的力学性能，维氏硬度和密度分别提高了 8.96% 和 4.37%，断裂韧性显著提高了 40.88%。样品中存在大晶粒和小晶粒，小晶粒为样品提供更好的硬度，而大粒径晶粒赋予样品优异的韧性。原位合成制备超细硬质合金是可行的，但易受晶粒尺寸分布不均匀和缺陷较多的影响。这可以通过减小原料粒径和适当优化烧结工艺来解决。 本研究为原位制备高强韧硬质合金提供了一种可行的途径。