Aging phenomena of dilute Al-Cu and Al-Cu-Sn alloys

Abstract

The aging phenomena of A1-1 and 2% Cu alloys containing Sn up to 0.136% at aging temperatures from 0° to 100°C were studied by means of electric resistivity measurements and high-resolution transmission electron microscopy. The aging rate of ternary A1-2 % Cu-Sn alloys is retarded compared with that of Al-Cu binary alloy at aging temperatures 0° to 75°C. The ternary A1-1% Cu-Sn alloy has the faster aging rate at 50°-75°C than the binary A1-1%Cu alloy. These noticeable facts would be explained by considering secondary defects formed at the early stage of aging. The secondary defects are different in their characteristics between the binary and ternary alloys and seem to play different roles of sink or source for vacancies according to the aging temperature and copper content.