On the grain boundary internal friction peak of α-brasses

A conventional Ke pendulum was used to investigate the temperature dependence of internal friction for thoroughly annealed samples of Cu-30% Zn. The relaxation peak observed at 330° C at a frequency of vibration 0.60 Hz was attributed to grain boundary diffusion. The energy activating the process amounted to 1.84 eV and characterized the activation energy for self diffusion in copper. The relaxation strength showed strain amplitude dependence, however, the activation energy and peak temperature did not show any amplitude dependence. The effect of solute atom concentration, cold work and vacancies was also tested.