FORMATION MECHANISMS OF GP ZONES AND THETA'-PHASE IN AL-CU CRYSTALS

In the previous report, it was shown by high resolution electron microscopy that four types of G.P. Zones are formed in Al-1.6 at%Cu crystals by aging, and that only one of them changes to theta'-phase. In the present report, local contents of Cu-atoms in these G.P. Zones have been estimated from the results obtained by an in-situ experiment of electron irradiation induced diffusion. Based on these results, mechanisms on the diffusion of Cu-atoms, the formation of Cu-atom clusters, the formation of various types of G.P. Zones, and the transition from G.P.zones to theta'-phase are discussed in terms of Al-Cu atom pairs.