The creep properties of unmodified and modified Al-Cu alloy with different content of La at 180℃

200 ℃ and 220 ℃ were analyzed comparatively.The microstructure evolution of unmodified and La modified ZL205 Aalloy at different temperature and applied stress was observed

and the mechanism of high temperature creep of La modified ZL205 Aalloy was described.The results reveal that

under the same creep temperature and applied stress

the steady creep rate of La modified ZL205 Aalloy is the lower than that of the unmodified ZL205 Aalloy

and the steady creep rate of 0.3%La modified ZL205 Aalloy is the lower 3

4

times than that of the unmodified ZL205 Aalloy.The apparent stress exponent of La modified ZL205 Aalloy is the higher than that of unmodified ZL205 Aalloy under the same temperature

and the apparent stress exponent of 0.3%La modified ZL205 Aalloy exhibits the highest value.The creep control mechanism of ZL205 Aalloy with and without La modification is characterized by high temperature dislocation slip or climb.After the modification of ZL205 Aalloy by adding La element

the amount of nano phase in the alloy is increased

and the high temperature stability of the nano phase is improved.The morphology change of discontinuous granular Al11La3 phase at the grain boundaries of0.3% La modified ZL205 Aalloy can be ignored before and after creep

which can play a role in preventing the grain boundary movement during the high temperature creep.