A mechanical model for embrittlement of polycrystalline Ni{sub 3}Al

Journal Article · Tue Jan 13 04:00:00 EST 1998 · Scripta Materialia

DOI:https://doi.org/10.1016/S1359-6462(98)00523-5· OSTI ID:611569

Han, G W; Lee, C S; Lai, J K.L. ^[1]; Feng, D ^[2]

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1. City Univ. of Hong Kong, Kowloon (Hong Kong). Dept. of Physics and Materials Science
2. Central Iron and Steel Research Inst., Beijing (China)

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.

• OSTI ID: 611569
• Journal Information: Scripta Materialia, Journal Name: Scripta Materialia Journal Issue: 4 Vol. 38; ISSN 1359-6462; ISSN SCMAF7
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM ALLOYS
DUCTILITY
FRACTURE MECHANICS
HYDROGEN EMBRITTLEMENT
MATHEMATICAL MODELS
NICKEL BASE ALLOYS
TEMPERATURE DEPENDENCE