Characterization of nanoscale NiAl-type precipitates in a ferritic steel by electron microscopy and atom probe tomography

Received 8 January 2010; received in revised form 2 March 2010; accepted 3 March 2010. published online 08 March 2010.

The microstructure of NiAl-type (β′) precipitates in an aged ferritic steel (Fe–12.7Al–9Ni–10.2Cr–1.9Mo, at.%) is characterized by transmission and analytical electron microscopy (AEM) and atom probe tomography (APT). The alloy shows a duplex precipitation of β′ particles: primary with an average diameter of 130nm and secondary with an average diameter of 3nm. Based on APT, the primary and secondary β′ have compositions of Ni41.2Al43.6Fe12.7Cr0.8Mo1.4 and Ni26.3Al41.6Fe26.9Cr3.3Mo1.7, respectively.

Keywords: Atom probe tomography, Analytical electron microscopy, Precipitation, Ferritic steel

a Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996, USA

b Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6136, USA

c Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208-3108, USA

d Department of Mechanical Engineering, Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong

e Materials Engineering, Auburn University, Auburn, AL 36849-5341, USA

Corresponding author. Tel.: +1 865 974 6356; fax: +1 865 974 4115.

PII: S1359-6462(10)00151-X

doi:10.1016/j.scriptamat.2010.03.013

Published by Elsevier Inc.

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