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Effect of initial gamma prime size on the elevated temperature creep properties of single crystal nickel base superalloysThe influence of initial gamma-prime size and shape on the high-temperature creep properties of two single-crystal Ni-base superalloys was investigated. The two alloys were chosen to represent different magnitudes of gamma/gamma-prime lattice mismatch. A range of initial microstructures was produced by various quenching and aging treatments. Creep-rupture testing at 1000 C was performed under stresses where gamma-prime directionally coarsens to form gamma/gamma-prime lamellae in the early portion of the creep life. Both alloys exhibited a peak in creep resistance as a function of initial gamma-prime size. The peak corresponded to an initial microstructure consisting of cuboidal precipitates aligned along 001 line directions. These aligned cuboidal gamma-prime particles directionally coarsened into a relatively perfect lamellar gamma/gamma-prime structure in the early stages of creep, whereas the more irregularly shaped and distributed gamma-prime particles in both under- and overaged material formed more irregular lamellae with more imperfections. The alloy with a lower magnitude of mismatch was less sensitive to initial gamma-prime size and shape.
Document ID
19880031657
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Nathal, M. V.
(NASA Lewis Research Center Cleveland, OH, United States)
Date Acquired
August 13, 2013
Publication Date
November 1, 1987
Publication Information
Publication: Metallurgical Transactions A - Physical Metallurgy and Materials Science
Volume: 18A
ISSN: 0360-2133
Subject Category
Metallic Materials
Accession Number
88A18884
Distribution Limits
Public
Copyright
Other

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