シリサイド系熱発電材料

Contents†

• Formation of beta-FeSi2 intermetallic compounds
• Fe-Si系熱発電材料の凝固組織

Formation of beta-FeSi2 intermetallic compounds†

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, I. Ohnaka: J. Mater. Sci. 32, (1997) 4603., http://dx.doi.org/10.1023/A:1004323930521
[2] I. Yamauchi, T. Nagase, 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, I. Ohnaka: J. of Mater. Sci. 37, 1429-1435 (2002)., http://dx.doi.org/10.1023/A:1014545302508

Fe-Si系熱発電材料の凝固組織†

REFERENCES
[1] T. Nagase, I. Yamauchi, I. Ohnaka, J. of alloys and compounds, 312, 295-301 (2000)., "Effect of rapid solidification on microstructure of various Fe29.5-xSi70.5+x(0≦x≦3.7) alloys", http://dx.doi.org/10.1016/S0925-8388(00)01142-7
[2] T. Nagase, I. Yamauchi and I. Ohnaka, J. of alloys and compounds, 316, 212-219 (2001)., "Eutectoid decomposition in rapidly solidified a-Fe2Si5-based thermoelectric alloys", http://dx.doi.org/10.1016/S0925-8388(00)01453-5