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Effects of Long-Term Service on The Aging Behavior of A Water-Quenched U6Nb Alloy

Published online by Cambridge University Press:  26 February 2011

Jikou Zhou  and
Luke L. Hsiung
Jikou Zhou
Affiliation:
zhou5@llnl.gov, Lawrence Livermore National Laboratory, Chemistry, Materials and Life Sciences Directorate, Lawrence Livermore National Laboratory, P.O. Box. 808, L-367, Livermore, CA, 94551, United States
Luke L. Hsiung
Affiliation:
hsiung1@llnl.gov, Lawrence Livermore National Laboratory, Livermore, CA, 94551, United States
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Abstract

Microhardness testing and transmission electron microscopy are used to study the effects of long-term service on the aging behavior of a water-quenched U-6wt.% Nb alloy when subjected to isothermal aging at 200°XC. The original α''c phase in the WQ-U6Nb alloy is found to become partially ordered over 18 years of aging at ambient temperatures, i.e., natural aging, forming a microstructure that is featured by antiphase domain boundaries (APBs). When subsequently aged at 200 °C, an ordered phase U3Nb is precipitated through a nucleation-and-growth mechanism, suppressing spinodal decomposition that occurs when the water-quenched alloy is artificially aged at the same temperature. The different phase transformation paths lead to different microhardness changes during artificial aging: the naturally aged alloy is more slowly hardened, but to a greater microhardness peak value.

Keywords

Uhardnesstransmission electron microscopy (TEM)
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 986: Symposium OO – Actinides 2006 – Basic Science, Applications and Technology , 2006 , 0986-OO07-01
Copyright
Copyright © Materials Research Society 2007

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