Experimental determination of phase diagram involving silicides in the Fe-Si binary system

Abstract

The phase diagram of the Fe-Si binary system was precisely determined using FE-EPMA/WDS and thermal analysis of DSC. It was confirmed that the concentration ranges of the β-Fe2Si and ζα-FeSi2 phases are slightly narrower and shifted toward higher Fe concentrations compared with the literature, and the other iron-silicide phases have low but certain concentration ranges less than 1 at%. The A2/B2/D03 order-disorder transition and Curie temperatures in the BCC phases exhibited concentration dependences consistent with those temperatures reported by Meco and Napolitano, and the Curie temperatures of the α”-Fe3Si (D03) alloys deviated higher from the extrapolated values of the α-Fe (A2) phase with increasing Si content and bent at the stoichiometric composition of 25 at%Si. Invariant reaction temperatures were mostly coincident with those of the phase diagram in the literature, except for the peritectoid temperature of the η-Fe5Si3 phase, whereas a small discrepancy was revealed in the solidus and liquidus lines.