Ultra-fine grained (UFG) hexagonal-close-packed (HCP) hafnium (Hf) and Hf-5wt%Y₂O₃ were prepared by a combination of high-energy ball milling and spark plasma sintering (SPS), and both possess high relative density (95% - 99%), high hardness, and low electrical conductivity. The Hf-5wt%Y₂O₃ (HYO) sample shows superior hardness of 12.11 GPa, which is about 6-7 times of that of coarse-grained Hf, and electrical conductivity of 2×10⁵ S/m, which keeps constant and is almost independent of temperature. It is very possible for HYO with these good properties to become an excellent plasma torch cathode. The analysis of the microstructure under transmission electron microscope (TEM) and scanning electron microscope (SEM) shows that the superior hardness of the samples originates from grain boundary strengthening and the pinning effects of the Y₂O₃ particles, while its almost temperature-independent electrical conductivity originates from the combining effects of the dispersion of large electrical resistivity particles Y₂O₃ and the dense high-angle grain boundaries.

采用高能球磨和放电等离子烧结（SPS）相结合的方法制备了超细晶（UFG）六方密排（HCP）铪（Hf）和Hf-5wt%Y ₂ O ₃ ，均具有高相对密度（95% - 99%）、高硬度和低电导率。Hf-5wt%Y ₂ O ₃ (HYO)样品的硬度高达12.11  GPa，约为粗晶Hf的6-7倍，电导率为2×10 ⁵ S/m，保持恒定，几乎与温度无关。具有这些优良特性的HYO极有可能成为优秀的等离子炬阴极。透射电子显微镜 (TEM) 和扫描电子显微镜 (SEM) 的显微组织分析表明，样品优异的硬度源于晶界强化和 Y ₂ O ₃颗粒的钉扎效应，而其几乎与温度无关电导率源于大电阻率颗粒Y ₂ O ₃的分散和致密的大角晶界的共同作用。