The effect of the process parameters of diffusion annealing for the ingots of alloy 2090 containing 0.12% ~0.15% Ce on the
distribution of alloying element inside the grains, mechanical properties of the alloy sheets and the
distribution or morphology of the dispersoids formed during hornogenizlng and the precipitates formed during ageing was studied. The results indicate that with the increase of first-stage or third-stage homogenization temperature the strength ot the as-aged sheets decreases, and rnedium first-stage or third-stage temperature can bring a certain benefit of fracture toughness and elongation to the sheets. Therefore, the sheets willdisplay a higher strength by the diffusion annealing of 350℃×10h＋500℃×16h or may show a higher fracture toughness and elongation by 450℃×10h＋500℃×10h＋520℃ ×6h to ingots. Higher first-stage temperature orlonger second-stage time of homogenization can make β' (Al3Zr) and T1 (Al2CuLi) compounds thicker and δ'(Al3Li)coats in the duplex δ'/β' precipitates split into granular shape. In the
microstructure of the sheets there are some finer and more dispersed duplex δ' /β' precipitates and non-uniform T1 phases in distribution and size under lower first-stage temperature. Higher third-stage temperature will cause the volume fraction of δ'particles to decreape and promote T1 phases to precipitate along grain boundaries with the addition of thick T1 phases inside grains.