Internal friction peak in cold-worked ''pure'' aluminum and aluminum alloys

Low frequency internal friction measurements have been made on ''pure'' aluminum and dilute aluminum alloys in heavily cold-worked states. A relaxation peak is observed at about 200 K (for 1Hz) even in specimens of nominally 4N or higher purity. This peak is considered to be the same as those previously reported by several researchers for dilute aluminum alloys of Cu, Mg or Ga. Among various elements so far examined (Cu, Si, Fe, Ge, Mg), Si has a dominant effect. The anomalous features of the peak, i.e. high activation energy and small preexponential factor for the relaxation time can be understood in terms of a model in which the anelastic elements exhibit strong interaction.