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Fatigue Crack Growth of Silicon Nitride at 1400°C: A Novel Fatigue‐Induced Crack‐Tip Bridging Phenomenon
Author(s) -
Liu ShihYu,
Chen IWei,
Tien TsengYing
Publication year - 1994
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.1151-2916.1994.tb06967.x
Subject(s) - materials science , equiaxed crystals , silicon nitride , annealing (glass) , paris' law , crack closure , composite material , cyclic stress , ceramic , silicon , fracture mechanics , metallurgy , microstructure
high‐strength Si 3 N 4 with elongated β‐Si 3 N 4 and equiaxed α‐sialon was tested in cyclic and static fatigue at 1400°C. At low stress intensity factors and high frequencies, the pullout process of the elongated grains was enhanced, which suppressed the crack growth. This provides a possible explanation for the increased lifetime under cyclic leading conditions reported for ceramics by several investigators. While crack‐healing by high‐temperature annealing was found to greatly reduce the subsequent static fatigue crack growth rate, it had only a modest effecf on cyclic fatigue and none at high frequencies.