Akio Yamamoto1, Hidetoshi Miyazaki2, Yoichi Nishino2 and Tsunehiro Takeuchi1
1Materials Science and Engineering, Graduate School of Engineering, Toyota Technological Institute, Nagoya 468-8511
In this study, we intended to increase the dimensionless figure of merit, ZT, of Al-Mn-Si based C54-phase using the precipitation of a small amount of Al-Mn-Si based C40-phase that possesses slightly smaller magnitude of both electrical resistivity and Seebeck coefficient. By knowing that both C54-phase and C40-phase in Al-Mn-Si alloy system are line compounds that are stabilized in a very narrow composition range, we prepared a series of samples by simply mixing two alloys consisting solely of C54-phase or C40-phase at [Al37(Mn26Ru3Re3Fe1)Si30]100-x[Al27.5(Mn29W3Fe1)Si39.5]x (x=0, 1, 3, 5, and 100). These initial alloys contained small amount of heavy elements for the reduction of lattice thermal conductivity. We found that the magnitude of Seebeck coefficient was kept essentially unchanged at x<3, while the lattice thermal conductivity and electrical resistivity were effectively decreased. The magnitude of ZT observed was increased by 16% from 0.38 of the single C54-phase at Al37(Mn26Ru3Re3Fe1)Si30 to ZT=0.42 at [Al37(Mn26Ru3Re3Fe1)Si30]97[Al27.5(Mn29W3Fe1)Si39.5]3.
thermoelectric composite, thermoelectric properties, silicide, mean free path of electron
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