Near-Net-Shape Fabrication of Thermoelectric Legs by Flash Sintering

Abstract

This study examines the near-net-shape fabrication, by flash sintering, of a sintered body for use in a thermoelectric module. Gas-atomized Fe2VAl powder was sintered with a current feed, for a duration on the order of seconds, using an apparatus specially devised for flash sintering. This produced sintered bodies in columnar form, with a diameter and height on the order of millimeters, which can be used for constructing thermoelectric modules without the need for a machining process, such as cutting or dicing. Although a slight reduction in density is observed, the crystal structure is unaffected by rapid heating and cooling. The magnitude of electrical and thermal conductivity is reduced, while the value of Seebeck coefficient is identical to that of a sample sintered by using conventional current sintering at 1373 K for 10 min. The significantly shorter sintering time can reduce energy consumption to less than 1 Wh, compared with the several hundred Wh required for conventional current sintering. Although it is still necessary to optimize the sintering conditions to overcome the reduction in density, the significant energy-conservation benefits of flash sintering have great practical appeal, especially for fabricating sintered bodies constituting thermoelectric power generation devices used for energy recovery.