Influence of Microstructure on Creep Rupture
In this paper, the effect of microstructure on both the creep and creep rupture behavior of two commercial grades of vitreous bonded aluminum oxide was investigated. Deformation and fracture occurred within the ductile, intergranular phase of the material. The creep rate was relatively insensitive to the amount of intergranular phase, but was sensitive to structural details of that phase. The creep rate could be reduced by increasing both the degree of crystallization of the intergranular phase and the viscosity of residual glass within that phase. The time-to-rupture and the strain-at-rupture increased as the amount of intergranular phase within the material increased. In this regard, an increase in the amount of intergranular phase permitted greater accommodation of strain, and hence, blunting of cavities that nucleated during the creep process. The data fit a modified Monkman-Grant curve in which the Monkman-Grant coefficient was sensitive to both stress and the amount of intergranular phase. The Monkman-Grant coefficient was not sensitive, however, to the degree of crystallization of the intergranular phase.
KeywordsPorosity Crystallization Carbide Silicate Barium
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