ANELASTICITY OF ULTRAFINE-GRAINED POLYCRYSTALLINE GOLD

The internal friction Q(-1) and resonant frequency f were measured on ultrafine-grained Au specimens prepared by the gas deposition method over the temperature range from 80 to 830 K using a vibrating reed technique (at about 10(2) Hz). The grain size of the specimens was about 30 nm. The modulus defect Delta M/M = Delta(f(2))/f(2) showed pronounced recovery during annealing at 450-810 K. This recovery can possibly be ascribed to the annealing of lattice dislocations. At higher temperatures three Q(-1) peaks at around 460, 550 and 750 K were observed. From the behaviours during annealing it is shown that the 460 K peak can tentatively be ascribed to the motion of dislocations with many irregularities, including jogs, and the other two peaks are the ordinary grain boundary peaks. At lower temperatures two Q(-1) peaks were observed and their possible origins are discussed.