Abstract:

To understand deeply the influence of lithium on 7000 series aluminum alloys, to obtain the Li-containing high strength alloys with good performance, the 7000 series Li-containing alloys are studied. The phase transformation kinetietics of the 7000 series Li-containing alloys containing lithium is investigated in comparison with Li-free 7000 series alloys by small angel X-ray scattering (SAXS) experimental measurements. The parameters for precipitate mean size and volume fraction are obtained by SAXS theory, and the activation energy for three stages is further obtained on the basis of the above information, including nucleus, growing and coarsening. The results show that as compared with Li-free alloys, the precipitation process of growing and coarsening is slower and nucleus activation energy is smaller, but the activation energy of growing and coarsening is larger in Li-containing alloys. It suggests that nucleus formation is easier, but the precipitation coruse of growing and coarsening is more difficult in Li-containing alloys than in Li-free alloys.

Key words: SAXS,  , 7000 , series , aluminium , alloy,  , Li,  , kinetics,  , precipitate , size,  , precipitate , volume , fraction,  , activation , energy