The effects of La on the microstructure and corrosion behavior of ADC12-xLa（x=0

0.3

0.6

0.9）alloy were investigated by optical microscope（OM）

scanning electron microscope（SEM）and energy disperse spectrometer（EDS）.The results show that when La content is increased from 0 to 0.6%

the morphology of primaryα-Al

eutectic Si and Al

8

SiFe

2

phases in the ADC12 alloy is refined gradually and the corrosion resistance is improved gradually.When rare earth La is less than 0.6%

it can be adsorbed at the surface of cathode phase during the modified process

thus forming a layer of rare earth oxidation film between the cathode and the anode.The rare earth oxidation film hinders the flow of corrosion electrons and improves the corrosion resistance of the ADC12 alloy.When the La content reaches 0.9%

a large amount of La-Al-Cu phases are generated in the alloy

which acts as a cathode phase in the alloy

resulting in the decrease of corrosion resistance of ADC12-0.9 La alloy.