Four types of 7050 aluminum alloys with different scandium addition were prepared

and effects of scandium on the microstructure

mechanical properties and recrystallization behaviour of 7050 alloy were investigated.The results show that scandium has a remarkable refining effect on the microstructure of as-cast 7050 alloy

and the grains in the alloy are transformed to fine equiaxed grain from coarse dendrite with increasing in scandium content.The tensile properties of the alloy are obviously enhanced with absence of decreasing the plaseticity of the alloy by adding a small amount of scandium to7050 alloy

and the best tensile properties can be obtained with the scandium content of 0.26%.However

it has no obvious effect on the mechanical properties of the alloy by adding more scandium to 7050 alloy.Compared with that of the 7050 alloy without addition of scandium

the recrystallization temperature of the 7050 alloy with the scandium content of 0.26%rises

and the starting recrystallization temperature of the alloy is raised to above 480 ℃.