Microstructural evolution of a MCrAlY coating upon isothermal annealing

Journal Article · Mon Dec 15 04:00:00 EST 2008 · Materials Characterization

DOI:https://doi.org/10.1016/j.matchar.2008.03.011· OSTI ID:21192572

Nijdam, T J ^[1]

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1. Department of Materials Science and Engineering and Materials Innovation Institute M2i, Delft University of Technology, Mekelweg 2, 2628 CD Delft (Netherlands)

The microstructural evolution of a freestanding {gamma} + {beta} NiCoCrAlY coating, as deposited by electron beam physical vapor deposition, was studied following isothermal annealing at 1373 K. Electron backscatter diffraction (EBSD) was used to characterize the crystallographic texture, grain and phase boundary population and the size and distribution of the grains in the coating as a function of annealing time. The as-deposited coating consisted of small equiaxed grains near the bottom, and large columnar grains near the surface of the coating. A phase separation process inside the columnar grains resulted in a local microstructure consisting of a periodic arrangement of {gamma} and {beta} lamellae, linked to each other according to the Kurdjumov-Sachs orientation relationship. Upon annealing, equiaxed-shaped grains formed within the coating at the expense of the columnar grains. The formation of the equiaxed grains corresponded with an increase of the total interface length per unit area in the coating. Upon prolonged annealing, growth of the equiaxed grains occurred according to a power law with a time exponent n of 2.

• OSTI ID: 21192572
• Journal Information: Materials Characterization, Journal Name: Materials Characterization Journal Issue: 12 Vol. 59; ISSN 1044-5803; ISSN MACHEX
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM ALLOYS
ANNEALING
BACKSCATTERING
CHROMIUM ALLOYS
CRYSTALLOGRAPHY
ELECTRON BEAMS
ELECTRON DIFFRACTION
GRAIN GROWTH
MICROSTRUCTURE
NICKEL ALLOYS
PHYSICAL VAPOR DEPOSITION
TEMPERATURE RANGE 1000-4000 K
YTTRIUM ALLOYS