ISIJ International
Online ISSN : 1347-5460
Print ISSN : 0915-1559
ISSN-L : 0915-1559
Atom-probe- and X-ray Diffraction Analysis of the Composition and Structure of Precipitates Formed on Tempering of Ternary Iron-Carbon-Nitrogen Martensites
A. BöttgerM. J. van GenderenS. J. SijbrandijE. J. MittemeijerG. D. W. Smith
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1996 Volume 36 Issue 7 Pages 764-767


X-ray diffraction analysis showed that both α''-type precipitates (as in Fe-N) and ε/η-type precipitates (as in Fe-C) develop in ternary Fe-C-N martensite upon tempering below 450 K. Atom-probe analysis was used to study the distribution of the interstitial atoms on a local scale. Most of the enriched regions formed after tempering contain both nitrogen and carbon atoms, but in an enriched region one type of interstitial is dominant. The carbon-rich regions contain a significantly larger amount of total interstitial atoms than the nitrogen-rich regions. The total interstitial amounts are close to that in ε/η for the carbon-rich regions and close of that in α'' for the nitrogen-rich regions. This suggests that upon tempering Fe-C-N martensite nitrogen atoms reside preferentially in an α''-type structure and carbon atoms reside preferentially in an ε/η-type structure, but that coprecipitation of nitrogen and carbon atoms occurs to a limited extent as well.

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© The Iron and Steel Institute of Japan
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