7075 aluminum alloys containing erbium（mass fraction 0.30%）were prepared by ingot metallurgy method.Effects of adding erbium and the retrogression and re-aging（RRA）treatment process on microstructure of the alloy were analyzed by optical microscopy

scanning electron microscopy and spectroscopy

and the mechanical properties were also examined to optimize the heat treatment.The results show that with 0.30% Er addition

the grain sizes of alloy are refined greatly.After T6aging treatment

the tensile strength and yield strength of the alloy reach 585 MPa and 528 MPa

respectively

with 8.5%of elongation and 724of the quality factor.Compared with those of alloy with Er free

the above properties are improved by 2.63%

2.33%

21.43% and by 3.87%

respectively.The tensile strength and yield strength of the 7075alloy with 0.3% Er after optimized retrogression and re-aging（RRA）treatment process at 120℃for 16hand at 180℃for 10min as well as at 120℃for 16h

reach645MPa and 603MPa

respectively

with 11%of elongation and 801of the quality factor.After RRA treatment

the mechanical properties are increased dramatically.Compared with the T6treatment

the above properties are improved by 10.26%

14.20%

29.41%and by 10.64%

respectively.