Partition of solute elements during solidification of iron-carbon-chromium alloys

Abstract

The partition coefficients of chromium between austenite and liquid iron,kCrA/L, were determined from the experiment of rapid cooling of iron-carbon hypo-eutectic alloys containing a small amount of chromium from coexisting solid—liquid states; the partition coefficients between eutectic and its liquid,k0,Cr, andk′0,Cr, for the stable and metastable eutectic solidifications were obtained from the zone-melting experiment of iron—carbon eutectic alloys containing a small amount of chromium. Chromium was rejected to liquid iron on the crystallization of primary austenite,kCrA/L 1. The relationship between effective and equilibrium partition coefficients given by Burtonet al. was observed for the results of the zone melting experiment and, from the relationship, the thickness of boundary layer in the liquid ahead of the solid—liquid interface was found to be 0.17 mm for the stable system and 0.11 mm for the metastable system. Thermodynamic calculation of the partition coefficients of chromium and carbon proved to represent the observed partition coefficients well.