Preparation of iron disilicide by sintering with Cu addition and their thermoelectric properties

The effects of Cu addition to /spl beta/-FeSi/sub 2/ on the pressureless sintering behavior and thermoelectric properties have been investigated. The transformation to the /spl beta/-phase from the /spl alpha/+/spl epsiv/ phase is significantly promoted by Cu addition because the supply of Si atoms for the /spl epsiv/-phase is enhanced through the Cu-Si liquid phase. Densification of the compacts is also remarkably promoted by the liquid phase sintering. The thermoelectric properties are compared to the conventionally hot-pressed samples. The Seebeck coefficient and resistivity are lower than those of the hot-pressed samples. Many small pores are detected in the pressureless sintered samples based on SEM observations, which effectively lowers the thermal conductivity. The figure of merit similar to the hot-pressed samples is obtained for the sample with a 4 wt.% Cu addition.