THERMAL RELAXATION OF INITIALLY FRACTAL GRAIN-BOUNDARIES

The concept of fractal geometry is used to describe serrated and rugge d grain boundaries in the pure materials Zinc and Titanium after defor mation and heat treatment. The fractal dimension of the grain boundari es are determined by application of optical and scanning electron micr oscopy over a wide range of magnifications. Measurements of the coarse ning kinetics of the initially fractal-like grain boundaries during is ochronous as well as isothermal annealing are presented. The results o f the annealing experiments can be explained by an analytic fractal co arsening model yielding the observed dependency of the time law of gra in boundary smoothing on the initially fractal dimension of the grain boundaries. The results are supported by a Monte Carlo simulation of t he smoothing process of single initially fractal grains.