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The Morphology of Widmanstatten Cementite Laths

Published online by Cambridge University Press:  02 July 2020

R. W. Fonda  and
M. V. Kral
R. W. Fonda
Affiliation:
Naval Research Laboratory, Code 6324, Washington, DC20375, USA
M. V. Kral
Affiliation:
University of Canterbury, Department of Mechanical Engineering, Christchurch, New Zealand
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Extract

The proeutectoid precipitation of Widmanstatten cementite has recently been shown to occur in two morphologies, either as broad monolithic plates or as aggregates of narrow laths, in a Fe-13 wt% Mn-1.3 wt% C steel, see Figure 1. Each of these morphologies correlates to a specific orientation of the cementite crystal within the austenite matrix; precipitates with a Pitsch orientation relationship adopt the monolithic plate morphology while precipitates with a Farooque-Edmonds orientation relationship develop as laths. In this paper, we examine the morphology and interfacial structure of these Widmanstatten cementite laths.

The typical three-dimensional morphology of Widmanstatten cementite laths can be revealed by etching with a 10% nitric acid solution in methanol. This procedure selectively etches the austenite matrix without affecting the cementite precipitates (see Figure 1). By similarly etching an electropolished thin foil TEM sample, the three-dimensional morphology and internal structure of entire electron transparent cementite precipitates can be examined.

Type
Phase Transformations
Information
Microscopy and Microanalysis , Volume 6 , Issue S2: Proceedings: Microscopy & Microanalysis 2000, Microscopy Society of America 58th Annual Meeting, Microbeam Analysis Society 34th Annual Meeting, Microscopical Society of Canada/Societe de Microscopie de Canada 27th Annual Meeting, Philadelphia, Pennsylvania August 13-17, 2000 , August 2000 , pp. 342 - 343
Copyright
Copyright © Microscopy Society of America

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References

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