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High‐Temperature Failure of Polycrystalline Alumina: II, Creep Crack Growth and Blunting
Author(s) -
BLUMENTHAL W.,
EVANS A. G.
Publication year - 1984
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.1151-2916.1984.tb19512.x
Subject(s) - creep , materials science , stress intensity factor , composite material , power law , crystallite , displacement (psychology) , crack closure , stress (linguistics) , ceramic , intensity (physics) , exponent , fracture mechanics , metallurgy , optics , psychology , linguistics , statistics , philosophy , mathematics , physics , psychotherapist
Creep crack growth in fine‐grain alumina is measured by using surface cracks. A narrow power‐law crack growth regime occurs at both 1300° and 1400°C, wherein the power‐law exponent and activation energy are comparable to steady‐state creep values. Asymptotic crack velocity behavior is exhibited near both the critical stress intensity factor, K C , and the crack growth threshold, K th . The threshold occurs near 0.4 K 1C at both 1300° and 1400°C and is associated with a transition in the size and distribution of damage. Displacement measurements indicate that crack tip damage exerts a strong influence on the displacement field, as predicted by recent theories. Furthermore, use of the stress intensity factor as a loading parameter does not produce adequate correlation with displacement measurements and is, therefore, not strictly suitable for nonlinear creeping ceramic poly crystals.