Effects of Ce or La addition on microstructure and mechanical properties of the Al-8.5Mg-0.5Mn aluminum alloy were investigated by means of optical microscopy（OM）

tensile test

scanning electron microscope（SEM）and energy spectrum analysis（EDS）.The results indicate that microstructure of the alloy can be refined via adding Ce or La

which is changed from dendritic morphology and to indistinct dendritic morphology and to equiaxed grain structure.A little Al4 Ce with fish-bone shape can be generated in the alloy with Ce addition

while absence of coarse Al-La phase can′t be observed in phase and grain boundary of the alloy with La addition.The mechanical properties of high-magnesium aluminum alloy can be improved to some certain with the addition of Ce or La

however their trend is almost the same.There are two peak values as follows:the first tensile strength peak value of 180

1

90MPa with Ce or La addition of about 0.25%;the second peak value of 220

2

30MPa with Ce or La addition of 1.5%.The elongation of alloy with La is the higher than that of ones with Ce.