The measurement of compressive creep deformation and damage mechanisms in a single-phase alumina part II - Correlation of creep cavitation and grain boundary sliding
Cr. Blanchard et al., The measurement of compressive creep deformation and damage mechanisms in a single-phase alumina part II - Correlation of creep cavitation and grain boundary sliding, J MATER SCI, 33(20), 1998, pp. 5049-5058
It has been theorized that stochastic grain boundary sliding (GBS) is the p
rimary driving force for the nucleation., growth, and coalescence of caviti
es located on the grain boundaries of polycrystalline ceramics undergoing c
reep. This paper reports on the results of co-ordinated measurements of bot
h GBS and creep cavitation during the creep of a single-phase alumina. Cons
tant compressive stress creep experiments were performed at a temperature o
f 1600 degrees C, and stress levels of 70, 100, and 140 MPa. Small angle ne
utron scattering measurements (SANS) show that cavities nucleate continuous
ly due to creep at all three stress levels, and that since negligible cavit
y growth was measured, creep cavitation appears to be ruled by a nucleation
rather than a growth process. Also, at a constant creep temperature, the n
umber and volume of cavities measured was observed to decrease with a decre
ase in the applied stress. GBS displacements reported in Part 1 of this pap
er [1] are related to the number of cavities nucleated per unit volume and
shown to relate directly, thereby providing experimental evidence that GBS
may act as the driving force for creep cavitation. (C) 1998 Kluwer Academic
Publishers.