The β-FeSi2 Formation and Thermoelectric Power of the FeSi2+Co Base Alloys


Temperature dependence of thermoelectric power and resistivity was measured for the β-FeSi2 based cast alloys on which n-type Co doping was performed with or without Cu addition. The Cu-free alloy shows a homogeneous eutectic microstructure consisting of metallic phases α-FeSi2 and ε-FeSi, while the Cu-doped alloy has a quite heterogeneous microstructure dominated by coarse ε-FeSi dendrites in the α-FeSi2 matrix. Adequate heat treatment condition for the semiconductor β-FeSi2 phase formation has been evaluated as annealing at 923 K for less than 50 h, which is lower in temperature and shorter in duration than previously reported for alloys prepared by powder metallurgy. The resistivity measurement with the aid of microstructure observation has revealed that the β-FeSi2 formation takes place and almost finishes at very early stage of annealing process. Addition of Cu effectively promotes the β-FeSi2 formation rate of the present cast alloys.

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Authors are deeply grateful to Dr. Kazuhiro Hasezaki, Mitsubishi Heavy Industries Ltd., for his fruitful comments.

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Correspondence to Yoshisato Kimura.

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Kimura, Y., Shindo, K. & Mishima, Y. The β-FeSi2 Formation and Thermoelectric Power of the FeSi2+Co Base Alloys. MRS Online Proceedings Library 646, 389–394 (2000).

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