The effects of single Sr or B content and Sr-B compound addition were analyzed on microstructure and thermal and electric conductivity of ADC12 alloy for LED radiator. The results reveal that with the addition of 0.04% B

the α-Al grains in ADC12 can be refined

thus improving the hardness of the alloy

however

its electrical and thermal conductivity can be weaken to some extent. With adding 0.04% Sr

the size of eutectic silicon and the secondary dendrite arm spacing in the ADC12 alloy are decreased to a certain extent

and its performances are enhanced compared with those of the original alloy. With compound addition of 0.04% Sr and 0.04% B

the modification effect of eutectic silicon in the ADC12 alloy can be improved and the secondary dendrite arm spacing reaches the smallest values. The eutectic silicon is converted from fine fiber shape to short rod shape and granular shape

which reduces the electron transport resistance and thus enhances the electrical conductivity and thermal conductivity of the alloy.