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

The bamboo boundary internal friction (BB) peak observed in high-purit y aluminium was shown to be connected with the existence of dislocatio n substructures nearby the bamboo boundary. It is shown that the BE pe ak is reduced in specimens quenched from high temperatures and changes when the quenched specimen is aged at various temperatures, and disap pears when aged at lower temperatures. TEM observation made after inte rnal friction measurement shows that the configuration of the dislocat ion substructures changes after quenching and aging treatments. The co nfigurations responsible for the BE peak and for the complementary pea k appearing at a much higher temperature (HT peak) are determined by c omparing the results of internal friction measurement and TEM observat ion. The condition of appearance of the BE peak predicted by the four- parameter mechanical model is confirmed.