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Effects of Tantalum on the Temporal Evolution of a Model Ni-Al-Cr Superalloy During Phase DecompositionThe effects of a 2.0 at.% addition of Ta to a model Ni-10.0Al-8.5Cr (at.%) superalloy aged at 1073 K are assessed using scanning electron microscopy and atom-probe tomography. The gamma'(Ll2)-precipitate morphology that develops as a result of gamma-(fcc)matrix phase decomposition is found to evolve from a bimodal distribution of spheroidal precipitates, to {001}-faceted cuboids and parallelepipeds aligned along the elastically soft {001}-type directions. The phase compositions and the widths of the gamma'-precipitate/gamma-matrix heterophase interfaces evolve temporally as the Ni-Al-Cr-Ta alloy undergoes quasi-stationary state coarsening after 1 h of aging. Tantalum is observed to partition preferentially to the gamma'-precipitate phase, and suppresses the mobility of Ni in the gamma-matrix sufficiently to cause an accumulation of Ni on the gamma-matrix side of the gamma'/gamma interface. Additionally, computational modeling, employing Thermo-Calc, Dictra and PrecipiCalc, is employed to elucidate the kinetic pathways that lead to phase decomposition in this concentrated Ni-Al-Cr-Ta alloy.
Document ID
20090007811
Acquisition Source
Glenn Research Center
Document Type
Reprint (Version printed in journal)
Authors
Booth, Morrison, Christopher
(Northwestern Univ. Chicago, IL, United States)
Seidman, David N.
(Northwestern Univ. Chicago, IL, United States)
Noebe, Ronald D.
(NASA Glenn Research Center Cleveland, OH, United States)
Date Acquired
August 24, 2013
Publication Date
February 1, 2009
Publication Information
Publication: Acta Materialia
Publisher: Elsevier Science Publishers Ltd.
Volume: 57
Issue: 3
Subject Category
Metals And Metallic Materials
Report/Patent Number
E-16900
Funding Number(s)
CONTRACT_GRANT: DMR-080461
CONTRACT_GRANT: N00014-0610539
CONTRACT_GRANT: N00014-0400798
Distribution Limits
Public
Copyright
Other

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