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Creep Cavitation in Liquid‐Phase‐Sintered Alumina
Author(s) -
PAGE RICHARD A.,
LANKFORD JAMES,
CHAN K. S.,
HARDMANRHYNE KAY,
SPOONER S.
Publication year - 1987
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.1151-2916.1987.tb04948.x
Subject(s) - materials science , cavitation , creep , nucleation , equiaxed crystals , grain boundary , composite material , phase (matter) , grain boundary sliding , stress (linguistics) , growth rate , grain growth , grain size , metallurgy , thermodynamics , microstructure , chemistry , geometry , linguistics , physics , philosophy , organic chemistry , mathematics
The early stages of cavitation during compressive creep of a liquid‐phase‐sintered alumina have been characterized using small‐angle neutron scattering. Grain‐boundary cavities were found to nucleate throughout creep, although at a steadily decreasing rate. The cavities were located on two‐grain junctions as well as triple points and were spaced approximately 100 to 200 nm apart. The cavity spacing corresponded to the spacings observed for grain‐boundary ledges, suggesting that the ledges were the cavity nucleation sites. Cavity nucleation was also found to be relatively independent of the applied stress. This behavior has been rationalized based on the decreasing ratio of ɛ gbs /ɛ t , where ɛ gbs is the strain due to grain‐boundary sliding and ɛ t is the total strain, at increasing stresses. Cavity growth, on the other hand, was highly stress dependent. Above a certain “threshold” stress cavity growth was observed. In all cases, however, the observed growth was transient; i.e., the cavity growth rate decreased with time. Lowering the stress below the “threshold” resulted in a condition in which cavities nucleated but continued growth of the cavities did not occur. In all cases the cavities nucleated and grew, when growth did occur, with relatively equiaxed shapes.