FURTHER EXPERIMENTS ON THE BAMBOO BOUNDARY INTERNAL-FRICTION PEAKS IN HIGH-PURITY ALUMINUM

The bamboo boundary internal friction (BB) peak observed in high-purity aluminium was shown to be connected with the existence of dislocation substructures nearby the bamboo boundary. It is shown that the BE peak is reduced in specimens quenched from high temperatures and changes when the quenched specimen is aged at various temperatures, and disappears when aged at lower temperatures. TEM observation made after internal friction measurement shows that the configuration of the dislocation substructures changes after quenching and aging treatments. The configurations responsible for the BE peak and for the complementary peak appearing at a much higher temperature (HT peak) are determined by comparing the results of internal friction measurement and TEM observation. The condition of appearance of the BE peak predicted by the four-parameter mechanical model is confirmed.