In-situ primary Si and Al3Ni hybrid particles reinforced Al matrix composite tubes were fabricated by centrifugal casting.Microstructure and properties of the composites were investigated by OM（optical microscope）

XRD（X-ray diffraction）

SEM（scanning electron microscope） and Rockwell hardness tester.The results show that

the composite components produced possess microstructures accumulating lots of Al3Ni particles and a part of primary Si particles in the outer layer

and a little Al3Ni and lots of primary silicon particles in the inner layer

and no any primary particles in the middle layer.From outer layer to inner layer

the volume fraction of reinforcement particles are firstly decreased and then increased.The hardness of composites presents the same change rule as the volume fraction of particles.The movement rule of multiphase flow in the centrifugal field was analyzed.The distribution of reinforcement particles is relative to the density of primary Al3Ni and Si particles and collapse as well as adhesion each other under the high G parameter.