Untitled research work

The Al-4%Cu-Sn alloys having Sn up to 0.065% were solution-treated at 520560°C, quenched into iced water, up-quenched at 100400°C for 3min at maximum, quenched and finally aged at 50100°C. The aging rate of ternary alloys becomes greater in contrast to the usual understanding than that of binary alloy with increasing Sn contents, only when the specimen is up-quenched at temperatures from about 150 to 300°C. The fact is proved on the basis of the aged structures, in which, under the condition, G. P. zone size in ternary alloy is always larger than that in binary alloy. The special aging behavior of ternary alloy would be understood considering that the nature of clusters in ternary alloy should be different from that in binary alloy.