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本文采用EBSD、压痕法等测试手段,对放电等离子烧结(SPS)获得的(Φ45 mm×5 mm)大尺寸硬质合金试样不同部位的微观组织及其硬度分布进行了研究。结果表明,大尺寸试样内部存在显微组织和性能的差异,沿径向从试样中心到边缘,材料硬度明显增大;试样厚度方向(轴向)上,表面显微组织的均匀性明显优于心部的显微组织,且平均晶粒尺寸大于心部。主要原因是SPS烧结过程中试样内部从中心到边缘、从表面到心部存在由高到低的温度梯度,造成烧结试样显微组织的不均匀和径向硬度的梯度分布。
In this paper, the microstructure and hardness distribution of different parts of (Φ45 mm × 5 mm) large-size carbide samples obtained by spark plasma sintering (SPS) were studied by EBSD and indentation methods. The results show that there is difference of microstructure and properties inside the large-size specimen, and the hardness of the material increases obviously from the center of the specimen to the edge in the radial direction. The uniformity of the microstructure on the specimen in the thickness direction (axial direction) Obviously superior to the heart of the microstructure, and the average grain size is larger than the heart. The main reason is the temperature gradient from high temperature to low temperature inside the sample from the center to the edge during the SPS sintering process, which leads to the uneven microstructure and the gradient distribution of the radial hardness of the sintered sample.