Abstract
The aging phenomena of Al-3.8%Cu-Be alloys having up to 0.093%Be and Al-3.8%Cu-0.09%Be-0.05%Cd alloy were investigated mainly as a function of aging temperature and Be content by means of electrical resistivity and hardness measurements, and transmission electron microscopy. Specimens were solution-treated at 520°C for 2hr, quenched and subsequently aged at temperatures ranging from 0 to 200°C.
(1) The aging retardation or acceleration at low or high temperature was found to occur in the ternary alloys with increasing Be contents, but the extent was very small compared with Sn (Cd) containing alloys.
(2) The aging acceleration resulted from the fact that θ' phases easily formed in the matrix of ternary alloys in the same way as in Sn (Cd) containing alloys. Be rich phases which would act as heterogeneous precipitation sites for θ' phases were never observed in contrast to Sn (Cd) containing alloys in which Sn (Cd) rich phases have so far been observed.
(3) The above aging phenomena in the ternary alloys were enhanced by the addition of Cd, showing that the effect of additional elements didn't offset each other.
(4) The mechanism for the aging phenomena of Al-Cu-Be alloy was considered to be quite different from that of Al-Cu-Sn (Cd) alloys.
