The coupled solute drag effect during ferrite growth in Fe-C-Mn-Si alloys using controlled decarburization

The kinetics of ferrite growth in three Fe-C-Mn-Si quaternary alloys has been measured using controlled decarburization tests at four temperatures between 755 degrees C and 825 degrees C, and a critical, quantitative test of the existence of a coupled solute drag effect (CSDE) is performed. The Mn and Si binding energies and trans-interface diffusivities (critical inputs in solute drag modelling) are taken directly from analogous experiments recently reported for ternary Fe-C-Mn and Fe-C-Si systems. The net solute drag effect experimentally observed in the quaternary system is found to be significantly less than that predicted by modelling using binding energies and trans-interface diffusivities calibrated on the respective ternary systems, i.e. an anti-CSDE is observed. This surprising observation is discussed in the context of solute interactions within the migrating interface and a number of future directions requiring investigation are highlighted. (C) 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.