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Comparison of gamma-gamma Phase Coarsening Responses of Three Powder Metal Disk SuperalloysThe phase microstructures of several powder metal (PM) disk superalloys were quantitatively evaluated. Contents, chemistries, and lattice parameters of gamma and gamma strengthening phase were determined for conventionally heat treated Alloy 10, LSHR, and ME3 superalloys, after electrolytic phase extractions. Several of long term heat treatments were then performed, to allow quantification of the precipitation, content, and size distribution of gamma at a long time interval to approximate equilibrium conditions. Additional coarsening heat treatments were performed at multiple temperatures and shorter time intervals, to allow quantification of the precipitation, contents and size distributions of gamma at conditions diverging from equilibrium. Modest differences in gamma and gamma lattice parameters and their mismatch were observed among the alloys, which varied with heat treatment. Yet, gamma coarsening rates were very similar for all three alloys in the heat treatment conditions examined. Alloy 10 had higher gamma dissolution and formation temperatures than LSHR and ME3, but a lower lattice mismatch, which was slightly positive for all three alloys at room temperature. The gamma precipitates of Alloy 10 appeared to remain coherent at higher temperatures than for LSHR and ME3. Higher coarsening rates were observed for gamma precipitates residing along grain boundaries than for those within grains in all three alloys, during slow-moderate quenching from supersolvus solution heat treatments, and during aging at temperatures of 843 C and higher.


Document ID
20160001847
Acquisition Source
Glenn Research Center
Document Type
Technical Memorandum (TM)
Authors
Gabb, T. P.
(NASA Glenn Research Center Cleveland, OH United States)
Gayda, J.
(NASA Glenn Research Center Cleveland, OH, United States)
Johnson, D. F.
(NASA Glenn Research Center Cleveland, OH, United States)
MacKay, R. A.
(NASA Glenn Research Center Cleveland, OH, United States)
Rogers, R. B.
(NASA Glenn Research Center Cleveland, OH, United States)
Sudbrack, C. K.
(NASA Glenn Research Center Cleveland, OH, United States)
Garg, A.
(Toledo Univ. Toledo, OH, United States)
Locci, I. E.
(Toledo Univ. Toledo, OH, United States)
Semiatin, S. L.
(Air Force Research Lab. Wright-Patterson AFB, OH, United States)
Kang, E.
(Northwestern Univ. Evanston, IL, United States)
Date Acquired
February 16, 2016
Publication Date
February 1, 2016
Subject Category
Metals And Metallic Materials
Report/Patent Number
GRC-E-DAA-TN27598
E-19184
NASA/TM-2016-218936
Funding Number(s)
CONTRACT_GRANT: NNC13BA10B
WBS: WBS 081876.02.03.04.02.01
Distribution Limits
Public
Copyright
Public Use Permitted.
Keywords
Superalloys
Metallurgy
High Temperature
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