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Lattice Defects Affecting Moisture-Induced Embrittlement of Ni-based L12 Ordered Intermetallics

Published online by Cambridge University Press:  15 February 2011

T. Takasugi
Affiliation:
Institute for Materials Research, Tohoku University, Katahira 2–1–1, Aoba-ku, Sendai, 98077, Japan
S. Hanada
Affiliation:
Institute for Materials Research, Tohoku University, Katahira 2–1–1, Aoba-ku, Sendai, 98077, Japan
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Abstract

Moisture-induced embrittlement of Ll2 alloys (such as Ni3(Si,Ti) and Ni3AI) is observed by tensile test and SEM fractography. A variety of microstructures were prepared by selecting pre-deformation and heat treatment conditions. It is shown that tensile ductility and the associated fractography depend on structure as well as test atmosphere. Well-annealed specimens are susceptible to moisture-induced embrittlement while pre-deformed specimens are resistive to moisture-induced embrittlement. Also, this embrittlement is generally sensitive to the heat treatment scheme preceded by the pre-deformation. Results indicate that the embrittlement occurs when hydrogen is enriched on grain boundaries. On the other hand, the embrittlement can be suppressed when hydrogen is trapped at lattice defects such as dislocations and vacancies. These results are discussed in association with the kinetics of hydrogen in the pre-deformed microstructure.

Type
Research Article
Copyright
Copyright © Materials Research Society 1997

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References

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