Spark plasma sintering (SPS) investigations were carried out on three sets of Co specimens: untreated, high energy mechanically (HEMT) pre-treated, and nanomodified powders. The microstructure, density, and mechanical properties of sintered pellets were investigated as a function of various pre-treatments and sintering temperatures (700–1000 °C). Fine-grained sinters were obtained for pre-treated Co powders; nano-additives tended to inhibit grain growth by reinforcing particles at grain boundaries and limiting grain-boundary movement. High degree of compaction was also achieved with relative densities of sintered Co pellets ranging between 95.2% and 99.6%. A direct co-relation was observed between the mechanical properties and densities of sintered Co pellets. For a comparable sinter quality, sintering temperatures for pre-treated powders were lower by 100 °C as compared to untreated powders. Highest values of bending strength (1997 MPa), microhardness (305 MPa), and relative density (99.6%) were observed for nanomodified HEMT and SPS processed Co pellets, sintered at 700 °C.

中文翻译：

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高能机械处理与纳米改性相结合的钴粉火花等离子体烧结

在三组Co样品上进行了火花等离子体烧结（SPS）研究：未处理，高能机械（HEMT）预处理和纳米改性粉末。根据各种预处理和烧结温度（700-1000°C）对烧结球团的微观结构，密度和机械性能进行了研究。对于预处理的Co粉，获得了细粒的烧结体。纳米添加剂倾向于通过在晶界处增强颗粒并限制晶界移动来抑制晶粒生长。烧结Co球团的相对密度在95.2％至99.6％之间，也实现了高压实度。观察到烧结Co颗粒的机械性能和密度之间存在直接的相互关系。为了获得可比的烧结矿质量，与未处理粉末相比，预处理粉末的烧结温度降低了100°C。在700℃下烧结的纳米改性HEMT和SPS处理的Co球团，观察到了最高的弯曲强度（1997 MPa），显微硬度（305 MPa）和相对密度（99.6％）。