Effects of liquid-solid mixing and mixing temperature of Al-25Si alloy on the microstructure and properties as well as the relationship between microstructure with thermal expansion coefficient and wear resistance of Al-18Si alloy which was prepared by CDS（controlled diffusion solidification）were investigated.The results show that during the CDS

the desirable microstructure with uniformly distributed round primary Si phase can be observed with mixed solid pure-Al at 630℃ with liquid Al-25Si at 850 ℃alloy

and wear resistance of the alloy exhibits desirable.The lower linear expansion coefficient（15. 51×10-6℃-1 from 30℃to 300℃）of the Al-18Si alloy can be achieved by the mixing of pure-Al at 630 ℃and liquid Al-25Si at 900℃.The wear resistance of Al-18 alloy Si is mainly dependent on the size

morphology and distribution of primary silicon.