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Microstructure and Oxidation of a MAX Phase/Superalloy Hybrid InterfaceCorrosion resistant, strain tolerant MAX phase coatings are of interest for turbine applications. Thin Cr2AlC MAX phase wafers were vacuum diffusion bonded to an advanced turbine disk alloy, LSHR, at 1100 C. The interface, examined by optical and scanning electron microscopy, revealed a primary diffusion zone consisting of ~ 10 micrometers of beta-Ni(Co)Al, decorated with various NiCoCrAl, MC and M3B2 precipitates. On the Cr2AlC side, an additional ~40 micrometers Al-depletion zone of Cr7C3 formed in an interconnected network with the beta-Ni(Co)Al. Oxidation of an exposed edge at 800 C for 100 h produced a fine-grained lenticular alumina scale over Cr2AlC and beta-Ni(Co)Al, with coarser chromia granules over the Cr7C3 regions. Subsequent growth of the diffusion layers was only ~ 5 micrometers in total. A residual stress of ~ 500 MPa was estimated for the MAX phase layer, but no interfacial damage was observed. Subsequent tests for 1000 h reveal similar results.
Document ID
20150000193
Acquisition Source
Glenn Research Center
Document Type
Technical Memorandum (TM)
Authors
Smialek, James L.
(NASA Glenn Research Center Cleveland, OH United States)
Garg, Anita
(Toledo Univ. Toledo, OH, United States)
Date Acquired
January 6, 2015
Publication Date
July 1, 2014
Subject Category
Metals And Metallic Materials
Report/Patent Number
E-18892
GRC-E-DAA-TN13600
NASA/TM-2014-216679
Funding Number(s)
CONTRACT_GRANT: NNC13BA10B
WBS: WBS 473452.02.03.05.04.01.01
Distribution Limits
Public
Copyright
Public Use Permitted.
Keywords
heat resistant alloys
oxidation
diffusion
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