Development and Application of High Performance Thermoelectric Materials by Powder Metallurgical Procedure Using Mechanical Alloying.

热电材料的热电性能可用方程Z=q^2/rokappa表示，其中Q为热电功率，Rho为电阻率，kappa为导热系数。研究结果表明：1)机械合金化(MA)使β-FeSi2相和金属相(金属相或绝缘体)弥散，改善了材料的热电性能。结果表明，碳化硅颗粒的弥散减小了β-FeSi2的晶粒度和导热系数kappa，金属相的弥散降低了材料的电阻率。(2)将FeSi2与硅、碳颗粒进行MA反应，得到了弥散分布在20~30 nm之间的细小颗粒--β-FeSi2。分散的碳化硅微粒降低了β-FeSi_2的热导率kappa值，而不改变热电势Q和电阻率Ro，从而提高了β-FeSi_2的热电性能。3)添加Zr显著提高了β-FeSi_2的热电性能，尤其是高温下的电阻率。

The performance of the thermoelectric materials is represented by the equation of Z=Q^2/rhokappa, where Q is thermoelectric power, rho is electrical resistivity, and kappa is thermal conductivity.The results obtained are as follows :1) Dispersion of epsilon-phase and ZrSi (metallic phase) or SiC (insulator) by mechanical alloying (MA) improved the thermoelectric properties of beta-FeSi_2. It was found that the dispersion of SiC particles decreased the grain size of beta-FeSi_2 and thermal conductivity, kappa, and the dispersion of metallic phases decreased the electrical resistivity, rho.2) beta-FeSi_2 with dispersion of fine SiC particles (20-30nm) was obtained by MA of FeSi_2 with Si and carbon particles. Dispersion of SiC fine particles increased the performance of beta-FeSi_2 by decreasing thermal conductivity kappa without changes in thermoelectric power Q and electrical resistivity rho.3) Addition of Zr significantly increased the themoelectrical performance of beta-FeSi_2 by decreasing the electrical resistivity especially at high temperatures.