By adding different contents of Cu

Mg and rare earth element Ce to the 2D70aluminum alloys

microstructure of the alloy was analyzed by OM

SEM

EDS.The results reveal that with the increase of Cu content

the Al

9

FeNi phase in 2D70aluminum alloy is decreased gradually

resulting in the non-equilibrium eutectic reaction.The precipitated eutectic phasesθ-Al

2

Cu exhibits in the pattern of mesh or Chinese character.With the excessive content of Cu

Al

7

Cu4Ni phase and Al

7

Cu

2

Fe phase which are harmful to mechanical properties of the alloy are precipitated.After the addition of Mg element

excess Cu atoms are trapped to form a lamellar phase S-Al

2

CuMg

in which the Al

9

FeNi phase is affected slightly by Cu and hardly reduced.When rare earth element Ce is added

the solute redistribution of the Cu atom appears

so that it can be dissolved fully into the matrix.Thereby

the solid solubility of Cu in the aluminum alloy is increased

and a large amount of refractory phase are absent in the grain boundary

so that the microstructure of the alloy presents uniform with refinement of grain size.