DIFFUSION ALONG [001] TILT BOUNDARIES IN THE AU/AG SYSTEM .1. EXPERIMENTAL RESULTS

The parameter, delta(b)D(b)Ag, for the chemical diffusion of Ag along the tilt axes of a series of [001] symmetric tilt boundaries in the Au/Ag system, was measured as a function of temperature and tilt angle at relatively low temperatures. (D(b)Ag = boundary diffusivity; delta(b) = boundary thickness.) Sixteen boundaries were studied using a newly developed surface accumulation method. Delta(b)D(b)Ag was found to vary quite smoothly with tilt angle (i.e. no sharp minima or cusps at low-SIGMA misorientations were observed) in a manner consistent with the structural unit model. The activation energies were found to be smooth functions of the tilt angle and to lie in the range 0.70-0.85 eV. The pre-exponential factors in the Arrhenius expression for delta(b)D(b) were approximately 3 orders of magnitude smaller than many of those reported in the literature for diffusion at higher temperatures.