GRAIN-BOUNDARY AND INTERPHASE BOUNDARY SLIDING IN POWER LAW CREEP

The self-consistent theory for polycrystals and composites can be extended readily to consider the effect of grain boundary sliding where the sliding boundaries are treated as disk-shaped viscous heterogeneities of a critical volume fraction to result in contiguously connected boundary paths through the material. The approach leads to particularly simple visualizable effects of strain rate enhancement in creeping polycrystals with sliding boundaries and to readily obtainable asymptotic limiting behavior for completely relaxed boundaries over a certain range of strain rate sensitivity of the grain matrix. Finally, this approach can also be combined with a self-consistent model for creep in a heterogeneous alloy to determine the behavior of creeping composite alloys with sliding grain boundaries and entrapped interphase boundaries. © 1979.