Phase-partitioning and site-substitution patterns of molybdenum in a model Ni-Al-Mo superalloy: An atom-probe tomographic and first-principles study

Atom-probe tomography (APT) and first-principles calculations are employed to investigate the partitioning of Mo in the γ(f.c.c.)-and γ′(L12)-phases in a model Ni-6.5Al-9.9Mo at. % superalloy. Mo is experimentally observed to partition preferentially to the γ(f.c.c.)-matrix, which is consistent with...

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Bibliographic Details
Published in:Applied physics letters 2012-09, Vol.101 (12)
Main Authors: Tu, Yiyou, Mao, Zugang, Seidman, David N.
Format: Article
Language:English
Subjects:
Aluminum
Intermetallic compounds
Mathematical models
Molybdenum
Nickel base alloys
Partitioning
Radial distribution
Superalloys
Tomography
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Summary:Atom-probe tomography (APT) and first-principles calculations are employed to investigate the partitioning of Mo in the γ(f.c.c.)-and γ′(L12)-phases in a model Ni-6.5Al-9.9Mo at. % superalloy. Mo is experimentally observed to partition preferentially to the γ(f.c.c.)-matrix, which is consistent with the smaller value of the γ(f.c.c.)-matrix substitutional formation-energy, with a driving force of 0.707 eV for partitioning as determined by first-principles calculations. APT measurements of the γ′(L12)-precipitate-phase composition and Al-, Mo-centered partial radial distribution functions indicate that Mo occupies the Al sublattice sites of the Ni3Al(L12) phase. The preferential site-substitution of Mo at Al sublattice sites is confirmed by first-principles calculations.
ISSN:0003-6951
1077-3118
DOI:10.1063/1.4753929