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Author Han, G. W. ♦ Lai, J. K. L.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword MATERIALS SCIENCE ♦ HYDROGEN EMBRITTLEMENT ♦ NICKEL BASE ALLOYS ♦ ALUMINIUM ALLOYS ♦ MATHEMATICAL MODELS ♦ FRACTURE MECHANICS ♦ TEMPERATURE DEPENDENCE ♦ DUCTILITY
Abstract It is well known that polycrystalline Ni{sub 3}Al suffers from severe intergranular brittleness at ambient temperatures, even though single crystals of Ni{sub 3}Al are quite ductile and extensive plasticity can be observed on the intergranular fracture surface. For many years the intergranular brittleness of polycrystalline Ni{sub 3}Al has been considered to be intrinsical due to the presence of crack-like microcavities along the grain boundaries. The formation of these microcavities has been attributed to the strong directional bonding between Ni and Al atoms to form highly ordered structure. On the other hand, many experiments have recently shown that environmental embrittlement is a major cause of the poor ductility of Ni{sub 3}Al in air. The purpose of this paper is to set up a mechanical model on the embrittlement of polycrystalline Ni{sub 3}Al by considering the fracture mechanics of the microcavities, as well as the diffusion of hydrogen atoms toward the grain boundaries and the subsequent hydrogen embrittlement. Based on the proposed mechanical model, effects of strain rate, deformation temperature, environment and alloying on the ductility of polycrystalline Ni{sub 3}Al are discussed.
ISSN 13596462
Educational Use Research
Learning Resource Type Article
Publisher Date 1998-01-13
Publisher Place United States
Journal Scripta Materialia
Volume Number 38
Issue Number 4


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