Combined nano-SIMS/AFM/EBSD analysis and atom probe tomography, of carbon distribution in austenite/epsilon-martensite high-Mn steels

Abstract

We introduce a new experimental approach for the identification of the atomistic position of interstitial carbon in a high-Mu binary alloy consisting of austenite and epsilon-martensite. Using combined nano-beam secondary ion mass spectroscopy, atomic force microscopy and electron backscatter diffraction analyses, we clearly observe carbon partitioning to austenite. Nano-beam secondary ion mass spectroscopy and atom probe tomography studies also reveal carbon trapping at crystal imperfections as identified by transmission electron microscopy. Three main trapping sites can be distinguished: phase boundaries between austenite and epsilon-martensite, stacking faults in austenite, and prior austenite grain boundaries. Our findings suggest that segregation and/or partitioning of carbon can contribute to the austenite-to-martensite transformation of the investigated alloy. Crown Copyright (C) 2013 Published by Elsevier B.V. All rights reserved