The influence of rare earth element Ce on fatigue properites and fracture toughness for Al-Li 2090 alloy was studied, and the mechanism of extrinsic toughening and intrinsic toughening from Ce was explored. A significant improvement in ductility, fatigue life and fracture toughness can be achieved by adding minor Ce into 2090 alloy, which is basically attributed to intrinsic toughening effect from Ce, i.e., the role of thinning and dispersing T-1 phase. On the other hand, due to the role of restraining recrystallization by adding Ce, the fraction of recrystallized grains is decreased and the unrecrystallized grains are thinned. It is responsible for enhancing extrinsic toughening effect.
