ICAMS / Interdisciplinary Centre for Advanced Materials Simulation

Research Highlights

The role of silicon, vacancies, and strain in carbon distribution in low temperature bainite

S. Sampath, R. Rementeria, X. Huang, J. D. Poplawsky, C. Garcia-Mateo, F. G. Caballero, R. Janisch.

We investigated the phenomenon of carbon supersaturation and carbon clustering in bainitic ferrite with atom probe tomography (APT) and ab-initio density functional theory (DFT) calculations. The experimental results show a homogeneous distribution of silicon in the microstructure, which contains both ferrite and retained austenite. This distribution is mimicked well by the computational approach. In addition, an accumulation of C in certain regions of the bainitic ferrite with C concentrations up to 13 at % is observed. Based on the DFT results, these clusters are explained as strained, tetragonal regions in the ferritic bainite, in which the solution enthalpy of C can reach large, negative values. It seems that Si itself only has a minor influence on this phenomenon.

We compare the results of ab-initio calculations of carbon solubility with atom probe data to understand the influence of Si on the segregation of C in bainitic ferrite. Graphical abstract of Sampath et al.,Journal of Alloys and Compounds 673, 289-294, 2016, reprinted with permission from Elsevier.