Phase Transition and Thermoelectric Property of Ultra-Fine Structured β-FeSi₂ Compounds

Abstract:

FeSi2 compounds were fabricated by rapid solidification and hot pressing, which is considered to be a mass production technique for this alloy. Structural behavior of melt-spun ribbon during heat-treatment and Seebeck coefficient of the hot pressed bulk were systemically investigated and compared with conventionally fabricated alloys. The melt-spun ribbon consists of α-Fe2Si5 and ε-FeSi phase. With increasing annealing time, the phase transition to β-FeSi2 phase occurred more rapidly. 20 min of annealing is sufficient for a homogeneous formation of β-FeSi2 phase in melt-spun ribbon, while it is 100 h in as-cast alloy. In this research, the formation mechanism of β-FeSi2 phase during annealing is a transition of α+ε→β. The microstructure of sintered bulk generally consist of a randomly distributed β-FeSi2 phase with an average grain size of 0.9 μm. The increase of Seebeck coefficient in melt-spun and sintered specimen is due to fine grain size formed by rapid solidification.

• Periodical: Solid State Phenomena (Volume 118)
• Pages: 591-596
• DOI: https://doi.org/10.4028/www.scientific.net/SSP.118.591
• Online since: December 2006
• Authors: Soon Jik Hong, Chang Kyu Rhee, Byong Sun Chun
• Keywords: Fe Si Compounds, Heat Treatment, Rapid Solidification, Thermoelectric Material

References

[1] U. Birkholz, J. Schelm, Phys. Status Solidi. 27 (1968), p.413.

[2] T. Kojima, Phys. Status Solidi. A 111 (1989), p.233.

[3] W. S. Cho, S.W. Choi, K. S. Park, Mater. Sci. Eng. B68 (1999), p.116.

[4] H. Nagai, Mater. Trans., JIM 36 (1995), p.365.

[5] R. M. Ware, D. J. Mcneill, Proc. IEE. 111 (1964), p.178.

[6] I. Nishida, Phys. Re. B7 (1973), p.1710.

[7] U. Brikholz, 2 nd European Conference on Thermoelectric, Nancy, (1989).

[8] L. A. Salam, D. Richard, Matthews. H. Robertson, Materials & Design, 20 (1999).

[7] - 350 Tap Casting (p-type: Fe0. 95Mn0. 05Si2).

[7] - 250.