Temperature- and amplitude-dependence of internal friction in Cu-Zn-AI alloys

Internal friction of Cu-Zn-AI alloys,' which can transform into martensite either by cooling or by stressing, has been measured as a function of temperature and amplitude. The highest internal friction was observed around the transformation temperature. It was shown that the internal friction of the β-phase alloys is low compared with the internal friction of the martensite. By plotting the results in a Granato-Lücke plot, it could be shown that at high amplitude the movement of the martensite plate boundaries is responsible for the high damping and that at low amplitudes only the dislocations contribute to the damping.