THE LARGE-SCALE DEFORMATION OF POLYCRYSTALLINE AGGREGATES: COOPERATIVE GRAIN-BOUNDARY SLIDING

摘要

The mechanisms and processes of large-scale deformation of polycrystalline materials are exam- ined using model aggregates comprising circular or hexagonal bars. It is emphasized that cooperative grain- boundary sliding is essential to allow large-scale deformation, contradicting the conventional models for the superplastic deformation of polycrystalline materials which proceed with the sliding process via switching respective grains. Theoretical considerations of the effects of grain size and shape, grain-boundary phase, and of the dimension of test specimen on the cooperative grain-boundary sliding are made.