Internal nitridation behavior during long-term creep in a nickel-base superalloy

Internal nitriding is analogous to internal oxidation and is governed by the same physical and diffusive processes. While internal oxidation has been studied extensively, fewer reports are available in the literature on internal nitriding. High-temperature strength in most nickel-base superalloys re...

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Bibliographic Details
Published in:Scripta materialia 2001-06, Vol.44 (11), p.2641-2646
Main Authors: Dong, J.X, Sawada, K, Yokokawa, K, Abe, F
Format: Article
Language:English
Subjects:
Applied sciences
Creep
Cross-disciplinary physics: materials science
rheology
Deformation, plasticity, and creep
Exact sciences and technology
Internal nitridation
Materials science
Metals. Metallurgy
Physics
Properties and phenomena
Superalloy
Treatment of materials and its effects on microstructure and properties
Udimet 500
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Summary:Internal nitriding is analogous to internal oxidation and is governed by the same physical and diffusive processes. While internal oxidation has been studied extensively, fewer reports are available in the literature on internal nitriding. High-temperature strength in most nickel-base superalloys results from the presence of a high volume traction of small precipitates of the cubic gamma '-phase (Ni sub 3 (Al,Ti)), while the resistance to high-temperature corrosion is based on the ability to form compact chromia and alumina scales. Recently, some studies reported that these protective oxide scales may fail by repeated spalling and cracking, where high mechanical and thermal stresses act or erosion takes place. A depletion of the scale-forming elements can then result. As a consequence, a transition from external to internal oxidation can occur, enabling nitrogen from the combustion gas to penetrate into the base metal and form thermodynamically stable nitrides, such as AlN and TiN. An applied stress should accelerate and promote this process. However, most of relevant works have concentrated on short term, high temperature and no-stress exposures. Little data are available in the literature regarding the internal nitridation of superalloys during long-term creep at intermediate temperatures. The present work addresses this regime by characterizing the internal nitridation behavior of Udimet 500 superalloy during long-term creep up to approx =20,000 hours at 800 and 900 deg C in air.
ISSN:1359-6462
1872-8456
DOI:10.1016/S1359-6462(01)00953-8