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对接近CoSb3成分的Co-87.9wt.%Sb合金进行了Bridgman定向凝固和激光快速凝固实验。结果发现,定向凝固速率为2和5μm/s时,合金凝固组织只含有CoSb3和Sb相;而当凝固速率增大至20、100、500μm/s时,组织中含有CoSb、CoSb2、CoSb3和Sb四相,且随着凝固速率的增大,CoSb3相的含量逐渐减少。对于激光快速凝固,当扫描速率为5 mm/s时,合金凝固组织为典型的包晶组织,组织中有四相,分别为CoSb3、CoSb2、CoSb与Sb相;当扫描速率增大至10 mm/s时,CoSb2包晶相领先于CoSb初生相析出,组织中只含有CoSb3、CoSb2与Sb三相。因此,要获得含有大体积分数CoSb3相热电性能好的材料,需要在低的凝固速率下进行制备。
Bridgman directional solidification and laser rapid solidification experiments were performed on Co-87.9wt.% Sb alloy close to CoSb3. The results show that when the solidification rate is 2 and 5μm / s, the solidified microstructure of the alloy contains only CoSb3 and Sb phases. When the solidification rate increases to 20,100 and 500μm / s, the microstructure contains CoSb, CoSb2, CoSb3 and Sb Four phases, and with the increase of the solidification rate, the content of CoSb3 phase decreases gradually. For laser rapid solidification, the solidified microstructure of the alloy is a typical peritectic structure when the scanning rate is 5 mm / s. There are four phases in the microstructure, namely CoSb3, CoSb2, CoSb and Sb. When the scanning rate increases to 10 mm / s, the CoSb2 peritectic phase precipitates ahead of the CoSb primary phase, and the microstructure contains only CoSb3, CoSb2 and Sb phases. Therefore, to obtain a material containing a large volume fraction of CoSb3 phase thermoelectric properties, it is necessary to prepare at a low solidification rate.