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Figure 1
TTT Diagram of the eutectoid reaction of a-Fe2Si5 (a-Fe2Si5 -> b-FeSi2 + Si) [2].
Figure 2=
TTT Diagram of the eutectoid reaction of a-Fe2Si5 with 1.0 at.% Mn (a-Fe2Si5 -> b-FeSi2 + Si) [2].
Figure 3
Elements for the accelerating the eutectoid reaction of a-Fe2Si5 (a-Fe2Si5 -> b-FeSi2 + Si) [3].
Beta-FeSi2 with high thermoelectric properties cannot be directly obtained from the thermal melt. The extremely long annealing is necesary for obtaining b-FeSi2 phase. The b-FeSi2 phase formation can be accelerated by small amount of Cu addition, especially for the eutectoid reaction of a-Fe2Si5 (a-Fe2Si5 -> b-FeSi2+ Si) [1]. We firstly constructed TTT diagram of the eutectoid reaction (a-Fe2Si5 -> b-FeSi2+ Si) for the development of Fe-Si based thermoelectric materials [2]. The eutectoid reaction of a-Fe2Si5 (a-Fe2Si5 -> b-FeSi2+ Si) can be accelerated by the small amount of Cu, Pd and Au addition, while the phase transformation rate is not affected by Ag and Pt addition [3].
REFERENCES
[1] I. Yamauchi, A. Suganuma, T. Okamoto and I. Ohnaka: J. Mater. Sci. 32, (1997) 4603., http://dx.doi.org/10.1023/A:1004323930521
[2] I. Yamauchi, T. Nagase and I. Ohnaka: J. of alloys and compounds, 292, 181-190 (1999)., http://dx.doi.org/10.1016/S0925-8388(99)00155-3
[3] I. Yamauchi, T. Nagase and I. Ohnaka: J. of Mater. Sci. 37, 1429-1435 (2002)., http://dx.doi.org/10.1023/A:1014545302508
