Formation and Healing of Voids at the Metal-Oxide Interface in NiAl Alloys
Artikel i vetenskaplig tidskrift, 2009

The present investigation concerns the formation and healing of voids at the metal-oxide interface in beta-NiAl alloys. It is shown that transient cavities form at the metal-oxide interface during the initial stage of isothermal oxidation at 1,050 A degrees C. These voids disappear after a few hours of oxidation, due to their filling with oxide. It is proposed that the filling of the transient voids occurs through cracks in the outer oxide scale. This allows for an oxygen transport into the cavities where a new oxide is created and grows outwards from the metal surface. Pt-containing beta-NiAl alloys that have better resistance to oxide spallation show suppressed formation of cavities and/or a faster filling of voids. This is explained by the enhanced diffusion of Al in these materials.

scales

interdiffusion

pore formation

adherence

Diffusion

growth

cyclic oxidation behavior

nickel-aluminides

Transmission electron microscopy

Cavities

sulfur segregation

Vacancy injection

alpha-al2o3

Oxidation

Nickel aluminides

cavity formation

Författare

Henrik Svensson

Chalmers

Pavleta Knutsson

Chalmers, Teknisk fysik, Mikroskopi och mikroanalys

Krystyna Marta Stiller

Chalmers, Teknisk fysik, Mikroskopi och mikroanalys

Oxidation of Metals

0030-770X (ISSN) 1573-4889 (eISSN)

Vol. 71 3-4 143-156

Ämneskategorier

Metallurgi och metalliska material

DOI

10.1007/s11085-008-9132-z