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Models of High‐Temperature, Environmentally Assisted Embrittlement in Ceramic‐Matrix Composites
Author(s) -
Evans Anthony G.,
Zok Frank W.,
McMeeking Robert M.,
Du Zheng Z.
Publication year - 1996
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1996.tb08982.x
Subject(s) - materials science , embrittlement , composite material , ceramic matrix composite , ceramic , stress (linguistics) , oxide , matrix (chemical analysis) , fiber , diffusion , cracking , environmental stress fracture , corrosion , stress corrosion cracking , metallurgy , philosophy , linguistics , physics , thermodynamics
The intermediate‐temperature oxidation embrittlement, or ‘pest,’ effect found in ceramic‐matrix composites (CMCs) is shown to have features analogous to stress corrosion cracking. The behavior involves crack growth upon oxidation of the fibers or the fiber coatings to form an oxide that weakens the fibers. It has reaction‐ and diffusion‐controlled regimes. The former occurs at low stresses. The latter occurs at higher stresses. It is controlled by oxygen ingress through the matrix cracks. There is also a crack growth threshold. Expressions for the crack velocity above the threshold are derived as well as the stress dependence of the rupture life.