An experimental quenching study was made of the effects of impurity atoms (H, C) and solute atoms (Cu, Mg, Si) upon the formation of vacancy clusters, voids and faulted loops. In order to investigate the effect of residual gas atoms which were dissolved in the Al before quenching, some specimens were melted so as to remove them. Voids were observed in pure Al which was melted in a graphite boat, but voids did not form at all in Al that was melted in an alumina boat. This suggested that C atoms played an important role in the nucleation of voids. In quenched pure Al that was heated in H, a large number of voids formed, while voids did not form in Al which was heated in He. In quenched pure Al which was residual-gas free, and also free from C, only faulted loops were observed. In quenched dilute Al-Cu alloys, only faulted loops formed and the formation of voids was appreciably suppressed. Both faulted loops and voids formed in quenched Al-0.04at%Si and Al-0.04at%Mg specimens; even when they were melted in alumina under high vacuum. The results suggested that both H and C atom were responsible for the formation of voids in quenched pure Al. The Cu atoms tended to suppress void nucleation, while Si and Mg atoms tended to nucleate voids in quenched dilute Al alloys. Solute Cu atoms increased the number density of faulted loops.

Formation of Voids and Faulted Loops in Quenched Pure Aluminum and Dilute Alloys. Q.Chen, I.Mukouda, Y.Shimomura: Bulletin of the Faculty of Engineering of Hiroshima University, 1998, 47[1], 1-11