skip to main content


Title: Carbon concentration measurements by atom probe tomography in the ferritic phase of high-silicon steels

Current studies using atom probe tomography (APT) show that bainitic ferrite formed at low temperature contains more carbon than what is consistent with the paraequilibrium phase diagram. However, nanocrystalline bainitic ferrite exhibits a non-homogeneous distribution of carbon atoms in arrangements with specific compositions, i.e. Cottrell atmospheres, carbon clusters, and carbides, in most cases with a size of a few nanometers. The ferrite volume within a single platelet that is free of these carbon-enriched regions is extremely small. Proximity histograms can be compromised on the ferrite side, and a great deal of care should be taken to estimate the carbon content in regions of bainitic ferrite free from carbon agglomeration. For this purpose, APT measurements were first validated for the ferritic phase in a pearlitic sample and further performed for the bainitic ferrite matrix in high-silicon steels isothermally transformed between 200 °C and 350 °C. Additionally, results were compared with the carbon concentration values derived from X-ray diffraction (XRD) analyses considering a tetragonal lattice and previous APT studies. In conclusion, the present results reveal a strong disagreement between the carbon content values in the bainitic ferrite matrix as obtained by APT and those derived from XRD measurements. Those differences have beenmore » attributed to the development of carbon-clustered regions with an increased tetragonality in a carbon-depleted matrix.« less
 [1] ;  [2] ;  [1] ;  [2] ;  [1] ;  [1] ;  [1]
  1. Spanish National Research Council (CSIC), Madrid (Spain). Center for Metallurgical Research (CENIM), Dept. of Physical Metallurgy
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Science (CNMS)
Publication Date:
Grant/Contract Number:
AC05-00OR22725; RFSR-CT- 2014-00019
Accepted Manuscript
Journal Name:
Acta Materialia
Additional Journal Information:
Journal Volume: 125; Journal Issue: C; Journal ID: ISSN 1359-6454
Research Org:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences (CNMS)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
36 MATERIALS SCIENCE; Bainitic steel; Nanostructure; Tetragonal distortion; Atom probe tomography (APT); X-ray diffraction (XRD)
OSTI Identifier: