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Enhanced microstructural stability of gamma/gamma ' -strengthened Co-Ti-Mo-based alloys through Al additions

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Abstract
We studied the microstructural stability and high-temperature mechanical properties of gamma/gamma' Co-Ti-Mobased alloys of varying compositions (Co-12Ti-4Mo, Co-12Ti-4Mo-2Al, Co-12Ti-4Mo-4Al, Co-10Ti-4Mo2Al, and Co-8Ti-4Mo-4Al (at.%)) using electron microscopy and density functional theory. The Co-12Ti4Mo alloy underwent discontinuous precipitation into FCC (gamma) and D0(19) (chi) phases after aging at 800 degrees C for 500 h while the Co-12Ti-4Mo-4Al alloy maintained the gamma/gamma' microstructure. Al additions improved the stability of the gamma/gamma' microstructure by forming L2(1) (beta') precipitates along the grain boundaries, reducing the supersaturation of the gamma matrix and the FCC/L1(2) interface energy. The Co-1(2)Ti-4Mo-4Al alloy showed lower yield strength compared to the Al-free alloy, however, the difference in yield strength between these two alloys decreased with increasing temperature. This decrease is counterbalanced by a substantially enhanced specific yield strength at elevated temperatures as compared to other well-known Co-based alloys such as MarM302 and Co-9Al-9W. (C) 2021 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
Author(s)
고원석Hye Ji ImJae Bok SeolKenHee RyouPyuck-Pa ChoiTae Hyeok KangWon Seok Choi
Issued Date
2021
Type
Article
Keyword
Cobalt-based superalloysDensity functional theory calculationsInterface energyMechanical propertiesMicrostructural stability
DOI
10.1016/j.actamat.2021.117011
URI
https://oak.ulsan.ac.kr/handle/2021.oak/8979
https://ulsan-primo.hosted.exlibrisgroup.com/primo-explore/fulldisplay?docid=TN_cdi_crossref_primary_10_1016_j_actamat_2021_117011&context=PC&vid=ULSAN&lang=ko_KR&search_scope=default_scope&adaptor=primo_central_multiple_fe&tab=default_tab&query=any,contains,Enhanced%20microstructural%20stability%20of%20gamma%2Fgamma%20%27%20-strengthened%20Co-Ti-Mo-based%20alloys%20through%20Al%20additions&offset=0&pcAvailability=true
Publisher
ACTA MATERIALIA
Location
영국
Language
영어
ISSN
1359-6454
Citation Volume
214
Citation Number
1
Citation Start Page
117011
Citation End Page
117011
Appears in Collections:
Engineering > Material Engineering
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