Al-Cu-Li-Sc-Zr alloys with different Mg contents were prepared by vacuum induction melting. The effects of Mg content on the microstructure and properties of the alloy were investigated by OM

XRD

SEM and EDS. The results indicate that after Mg addition

the acicular AlLi phase in the alloy is decreased gradually with forming a new Al

2

MgLi eutectic phase

and the grain size of the alloy is decreased continuously. However

when the Mg content is excessive

the coarse eutectic phase at the grain boundary is increased continuously

which is adverse to the mechanical properties of the alloy. With the increase of Mg content

the strength of alloy is increased firstly and then decreased. In addition

Mg has a certain effect on the fracture mode of the alloy

resulting in the decrease of the plasticity. The hardness and tensile strength of the alloy are further improved by solution treatment

which significantly enhance the plasticity

while the yield strength is decreased due to the dissolution of strengthening phase. When the addition of Mg is 1%

the Al-Li alloy in solid solution state exhibits desirable comprehensive mechanical properties

where the hardness

tensile strength

yield strength and elongation of the alloy reach up to 131.1 HV

432.7 MPa

267.4 MPa and 7.62%

respectively.