Preparation of molybdenum-sodium alloy by spark plasma sintering

The molybdenum-sodium (Mo-Na) alloy was prepared by spark plasma sintering (SPS), and the effects of sintering temperature, pressure, heating rate, and holding time on the relative density of the Mo-Na alloy were investigated. The relative density and microscopic morphology of the Mo-Na alloy were characterized by means of scanning electron microscopy (SEM), density testing equipment, and other detection methods. Meanwhile, the densification process of the molybdenum-sodium alloy prepared by spark plasma sintering was analyzed. The results show that the sintering temperature and pressure are the main factors affecting the relative density of the Mo-Na alloy. The densification process of the Mo-Na alloy consists of four stages, namely, activation and purification of Mo-Na alloy powder particles; occurrence and formation of sintering necks; connection of sintering necks and liquid-phase filling diffusion; spheroidization of grains and uniform filling of the liquid phase. The maximum relative density of the as-sintered Mo-Na alloy is 98.68%, and the average grain size is less than 10 μm.