Development of thermoelectric borides by powder metallurgy method using metal boride interphases

Boron-based composite thermoelectric materials for high-temperature applications were fabricated using a liquid-phase sintering based on the eutectic reaction between boride and metals.Metals such as Ni, Co, Fe and Mn, which form eutectic liquid phases with boron, were added to the raw powder mixture of boron-based materials. All samples were sintered by powder metallurgy method using SPS. Due to the introduction of the eutectic liquid phase, the reaction of the boride phase was accelerated, and the densification of the boron-based composite material was achieved.The electrical conductivity was improved while maintaining the Seebeck coefficient around 200 μV/K, depending on the metal additives. Furthermore, it was observed that the thermal conductivity can be reduced due to the microstructural differences caused by the formation of the eutectic liquid phase and the difference in the wettability between the liquid phase and boride phase.