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Effect of Crack‐Interface Bridging on Subcritical Crack Growth in Ferrites
Author(s) -
Beauchamp Edwin K.,
Monroe S. L.
Publication year - 1989
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.1151-2916.1989.tb09705.x
Subject(s) - intergranular corrosion , materials science , intergranular fracture , transgranular fracture , crystallite , ceramic , composite material , fracture mechanics , manganese , fracture (geology) , metallurgy , microstructure
A transition between transgranular fracture and intergranular fracture in polycrystalline manganese zinc ferrites has been investigated by measuring subcritical crack growth in double‐cantilever‐beam specimens. Log velocity vs K 1 plots are like those for other ceramic materials with three well‐defined regions of growth. Unlike other ceramics, however, the K 1 values at which crack growth became critical showed large variations with relative humidity. Crack velocities depended on prior history and, at K 1 > 1.1 MPa · m 1/2 in dry N 2 , crack growth was intermittent. All of these features were related to an increase in intergranular fracture with K 1 . A model is presented to explain the data in terms of the generation ad removal of crack‐interface bridges which were produced by intergranular fracture.