The Equilibrium Diagram of the Fe-Cr-Si System

Abstract

On the Heterogeneous Equilibria relating to liquid phase in the iron-corner. By thermal analysis and microscopic examination, the melting points and the structural constituents of iron rich Fe-Cr-Si alloys containing up to 33% Si and up to about 50% Cr were determined. These alloys used were made of electrolytic iron, low carbon ferro-chromium and refined silicon by means of 3KVA. high frequency induction furnace. In this composition range, there lie five primary crystallization surfaces, on which α, δ, η, ε and ∑ phases crystallize out. The phase ∑ is the ternary compound based on the super lattice of FeCr. Theδ. and η phases are all proportionally miscible solid solutions of FeSi-CrSi and Fe5Si3-Cr5Si3, respectively. The 17 phase in the Fe-Si system is formed during cooling in solid by the peritectoid reaction α+δ →η, while in the ternary system, Fe-Cr-Si, this phase crystallizes out primarily on cooling from liquid. The following three invariant reactions take place; and these invariant points are at 7.5% Cr 21.0 % Si, 25.5% Cr 17.0%Si and 30.5% Cr 15.5% Si, respectively. © 1941, The Japan Institute of Metals. All rights reserved.