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

热电材料的性能由方程Z=Q^2/rhokappa表示，其中Q为热电功率，rho为电阻率，kappa为导热系数。结果表明：1)机械合金化（MA）使epsilon相与ZrSi（金属相）或SiC（绝缘体）分散，提高了β - fesi_2的热电性能。结果表明，SiC颗粒的分散降低了β - fesi_2的晶粒尺寸和导热系数kappa，金属相的分散降低了β - fesi_2的电阻率rho。2)用硅、碳粒子对FeSi_2进行能谱分析，得到了分散在20 ~ 30nm SiC的β -FeSi_2。SiC细颗粒的分散在不改变热电功率Q和电阻率rho的情况下，通过降低导热系数kappa提高了β - fesi_2的性能。3) Zr的加入降低了β - fesi_2的电阻率，显著提高了其热电性能，尤其是在高温下。

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.