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Nature of Environmentally Assisted Fractures in Polycrystals

Published online by Cambridge University Press:  03 September 2012

Leonardo GoluboviĆ  and
Anatoli Peredera
Leonardo GoluboviĆ
Affiliation:
Physics Department, West Virginia University, Morgantown, WV 26506
Anatoli Peredera
Affiliation:
Physics Department, West Virginia University, Morgantown, WV 26506
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Abstract

Environmentally assisted fracture is in practice one of the most important fracture modes. It is especially dramatic in polycrystalline super-alloys, which are believed to be embrittled by oxygen diffusing along their grain boundaries. We used a large scale atomistic Monte-Carlo simulation to study phenomena of the environmentally assisted fracture nucleation in solids with grain boundaries exposed to an oxygen atmosphere. We find nucleation of inter-granular microcavities in a region which is well in front of the oxidized zone of the sample, apparently due to inhomogeneous stresses induced by the presence of oxide particles. This effect increases with decreasing oxidation rate since then the oxidation front becomes fuzzier and inhomogeneous stresses stronger. These findings compare well with the experimental data on super-alloys which indicate that the environmental embrittlement effects are strong for slower oxidation rates, whereas at higher oxidation rates the embrittlement may be suppressed.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 367: Symposium P – Fractal Aspects of Materials , 1994 , 107
Copyright
Copyright © Materials Research Society 1995

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