Mg2Si and primary Si particle hybrid reinforced Al matrix gradient composites tubes were fabricated by hot mould centrifugal casting

and the raw tubes were machined into the cylinder line with 2

3

mm particle reinforced layer in thickness in the inner wall.The microstructure of the cylinder liner was observed by SEM（scanning electron microscope）and OM（optical microscope）.The results indicate that volumetric fraction of hybrid particles makes 30%

3

8% in the inner reinforced layer

while absence of hybrid particles in outer layer can be observed.Hardness and abrasion testing show that the reinforced layer exhibits a higher hardness and desirable wear resistance.Primary Si is dominant in subjecting frictional loading

and the Mg2Si phase plays a key role in reinforcing wear resistance.