Study of Energy Versus Misorientation for Grain Boundaries in Cold by Crystallite Rotation Method. 2. Tilt Boundaries and Mixed Boundaries

摘要

In Part I (Acta Met. 33, 1113 (1985)) small gold crystallites were welded to thin film single crystal gold substrates at different controlled misorientations to produce pure twist boundaries in the neck regions which could be observed directly by transmission electron microscopy. In the presnt work these experiments were extended to include pure tilt and also mixed (tilt/twist) boundaries. Upon annealing, the crystallites untilted and untwisted into several particular misorientations in order to reduce the boundary energy. The untilting and untwisting occurred by the observed climb of edge grain boundary dislocations (GBDs) and glide of screw GBDs respectively. The directions of the rotations were generally consistent with a boundary energy vs tiltwist ''surface'' constructed on the basis of the structural unit/GBD model for grain boundaries. Kinetic models for the untilting indicated that the climbing edge GBDs acted as efficient line sources/sinks and that the diffusional tranport was controlled by either lattice diffusion or edge GBD core diffusion for low-angle pure tilt boundaries and by grain boundary diffusion for high-angle mixed boundaries. (ERA citation 11:020270)