熔体旋甩工艺对Mg_(2)(Si_(0.4)Sn_(0.6))Sb_(0.015)固溶体微结构和热电性能的影响研究

Effect of Melt Spinning Process on Microstructure and Thermoelectric Properties of Mg_(2)(Si_(0.4)Sn_(0.6))Sb_(0.015)Solid Solution

Mg_(2)(Si,Sn)基材料是环境友好的热电材料,具有较好的应用前景。本工作采用熔体旋甩(MS)结合放电等离子烧结(SPS)技术(MS+SPS)制备了单相的Mg_(2)(Si_(0.4)Sn_(0.6))Sb0.015固溶体,通过将机械合金化(MA)与放电等离子烧结(SPS)技术(MA+SPS)结合制备的相同样品进行对比,研究MS工艺对样品微结构以及热电性能的影响。结果表明,MS得到的固溶体薄带主要由200~500 nm的小颗粒组成,将薄带研磨制粉经SPS烧结后得到的致密块体具有明显细化的晶粒和分布均匀的共格纳米析出相。与MA+SPS工艺制备的样品相比,MS+SPS制备的固溶体的迁移率明显降低,在一定温度范围内,电阻率略有升高,Seebeck系数显著增加,热导率和晶格热导率显著降低。MS+SPS制备的Mg_(2)(Si_(0.4)Sn_(0.6))Sb0.015固溶体热电性能明显提高,在643 K时其最大ZT值达到1.30。

Mg_(2)(Si,Sn)-based materials are a kind of environment-friendly thermoelectric materials with great application prospects.The single phase Mg_(2)(Si_(0.4)Sn_(0.6))Sb_(0.015)solid solution was prepared by melt spinning(MS)combined with spark plasma sintering(MS+SPS).By comparing with the same sample prepared by mechanical alloying(MA)combined with spark plasma sintering(MA+SPS),the effect of MS process on its microstructure and thermoelectric properties were studied.The results show that the solid solution thin belt obtained by MS is mainly composed of small particles of 200—500 nm.The obtained sinered dense buck material has obviously refined grains and uniformly distributed coherent nano precipitates.Compared with the samples prepared by MA+SPS process,the mobility of solid solution prepared by MS+SPS is significantly reduced,the resistivity increases slightly,the Seebeck coefficient increases significantly,and the thermal conductivity and lattice thermal conductivity decrease significantly.The thermoelectric properties of Mg_(2)(Si_(0.4)Sn_(0.6))Sb_(0.015)solid solution prepared by MS+SPS are significantly improved,and the maximum ZT value reached to 1.30 at 643 K.