GRAIN ROTATION IN THIN-FILMS OF GOLD

We present transmission electron microscope observations of microstruc tural development in thin, fine-grained, columnar, (111) textured film s of gold. In a sequential annealing experiment, we find that individu al grains constantly rotate about the film normal in apparently random , and randomly changing directions. This contributes to the rearrangem ent of grain boundaries by allowing their individual energies to vary, thus promoting triple-line motion. We perform an analysis of the kine tics of grain rotation: assuming that its rate is limited by grain bou ndary diffusion, we obtain very good agreement between the observed an d predicted rates and the rotation rate is predicted to be very sensit ive to the gain size. A simple computer model is developed to investig ate the structural consequences of grain rotation, which include reduc tion in the total grain boundary energy in a specimen, and changes in the populations of the various CSL-related boundaries. (C) 1998 Acta M etallurgica Inc.