Abstract
The Al-4wt%Cu alloys containing various amounts of Sn up to 0.101wt% were solution-treated at 520°C, quenched into iced water, kept in liquid nitrogen, and subsequently reverted at 200°C for 0.530min. The changes in electrical resistivity due to reversion were studied in detail in relation to the reverted structure by using a high resolution electron microscope. The main results were as follows:
(1) The resistivity in the quenched state was the highest in binary alloy and decreased in ternary alloys with increasing Sn contents. The resistivity decrease due to short-time reversion became smaller, while the subsequent decrease with reversion time became larger, as Sn contents increased.
(2) It was confirmed in transmission electron micrographs that, even in the short-time reversion of about 1min θ" phase formed in the binary alloy; and Sn-rich phase, in ternary alloys. Therefore, it was made clear that the uniform solid-solution with none of quench clusters was hardly obtained by usual reversion treatment at 200°C.
(3) The relation between resistivity changes due to reversion and reverted structures was discussed.
