CoSb_3纳米晶块体热电材料的制备研究

Preparation of Nanocrystalline CoSb_3 Bulk Thermoelectric Material by MA-SPS

采用机械合金化-放电等离子烧结工艺(MA-SPS), 在200℃～600℃之间制备了纳米晶CoSb3合金块体材料。采用XRD和TEM对材料的相组成和微观组织进行了测试分析。实验结果表明, 烧结前粉末为高能球磨得到的平均晶粒尺寸为20 nm～35 nm的纳米晶CoSb3粉末,SPS烧结后CoSb3合金块体的平均晶粒尺寸小于100 nm, 其致密度达到了91.3%～99.6%。CoSb3块体的晶粒尺寸随着烧结温度的降低而减小,而密度却随着烧结温度的升高而增加。CoSb3纳米晶块体热电材料的制备机理是MA使粉末晶粒细化到纳米级, 放电等离子烧结的快速、短时、低温和特殊烧结机理显著抑制了烧结时的晶粒长大。

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.