Preparation of nanocrystalline CoSb3 bulk thermoelectric material by MA-SPS

Nanocrystalline CoSb3 bulk alloys with relative density of 91.3%-99.6% were successfully prepared by mechanical alloying and spark plasma sintering (MA-SPS) at 200degreesCsimilar to600degreesC. The grain sizes were measured by X-ray diffraction, and fracture appearance and crystal structure were observed by SEM and TEM. The experimental results show that the average crystal grain sizes of bulk CoSb3 samples sintered by SPS from the powder with 20nm-35nm crystal grain size milled by MA are less than 100nm. The cystal size of the bulk CoSb3 decreases with the sintering temperature, and the density increases with the sintering temperature. The mechanism of preparing nanocrystalline bulk is that mechanical alloying makes the powder size to be fine to nanometer and the special fast, short time and low temperature technology of spark plasma sintering restrains the crystal grain to grow up.