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Phase Stability and Mechanical Properties of C-22 Alloy Aged in the Temperature Range 590 to 760°C for 16,000 Hours

Published online by Cambridge University Press:  10 February 2011

Tammy S. Edgecumbe Summers
Affiliation:
Lawrence Livermore National Laboratory, 7000 East Ave, Livermore, CA 94550, [email protected]
Mark A. Wall
Affiliation:
Lawrence Livermore National Laboratory, 7000 East Ave, Livermore, CA 94550, [email protected]
Mukul Kumar
Affiliation:
Lawrence Livermore National Laboratory, 7000 East Ave, Livermore, CA 94550, [email protected]
Steven J. Matthews
Affiliation:
Haynes International, Inc., 1020 W. Park Ave., Kokomo, IN 46904
Raú B. Rebak
Affiliation:
Haynes International, Inc., 1020 W. Park Ave., Kokomo, IN 46904
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Abstract

The phase stability of C-22 alloy (UNS #N06022) was studied by aging samples at 593, 649, 704 and 760°C for 2000 h (2.7 mo) and 16,000 h (1.8 yr). The tensile properties and the Charpy impact toughness of these samples were measured in the mill annealed condition as well as after aging. The microstructures of samples aged 16,000 hours were examined using scanning and transmission electron microscopy (SEM and TEM). Preliminary TEM results suggest that μse forms at all temperatures investigated. Discrete carbide particles in addition to a film with very uniform thickness which appears to be μ phase formed on grain boundaries in the sample aged at 593°C. The ordered Ni2(Cr, Mo) phase was also seen in this sample. At the higher aging temperatures, mainly μ phase forms covering all the grain boundaries and also distributed throughout the bulk. Although strength increased somewhat with aging. the ductility decreased due to the formation of these grain boundary precipitates and brittle intermetallics.

Type
Research Article
Copyright
Copyright © Materials Research Society 1999

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References

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