Effects of the Zr0.5Hf0.5FexCo1-xSb0.8Sn0.2/Fe3Sn2 half-Heusler composites on the ZT value

This study aims to evaluate the effect of a composite on the microstructures and the half-Heusler Zr0.5Hf0.5FexCo1 xSn0.2Sb0.8/Fe3Sn2 (x = 0.05, 0.1 and 0.2) on the ZT value. We demonstrate that the substitution of Fe for the Co site in Zr0.5Hf0.5FexCo1 xSn0.2Sb0.8 under the arc melting process is able to promote the occurrence of a second Fe3Sn2 phase. The in-situ formed Fe3Sn2 phase was evenly dispersed on the grain boundaries and increased with increasing amounts of Fe. Such structure morphology can be treated as Zr0.5Hf0.5FexCo1 xSn0.2Sb0.8/Fe3Sn2 (x = 0.05, 0.1 and 0.2) composites. The maximum substitution of the Co site by Fe is approximately 3.32 at.%. The effects of Fe doping on the Seebeck coefficient, electrical conductivity, and thermal conductivity of Zr0.5Hf0.5FexCo1 xSn0.2Sb0.8/Fe3Sn2 (x = 0.05, 0.1 and 0.2) composites have been investigated from 300 K to 900 K. The substitution of the Co site by Fe in Zr0.5Hf0.5FexCo1 xSn0.2Sb0.8 is effective in increasing the ZT value. The maximum ZT of Zr0.5Hf0.5Fe0.1Co0.9Sn0.8Sb0.2/Fe3Sn2 can reach 0.62 at 900 K after BM-SPS processing. (C) 2014 Elsevier B.V. All rights reserved.