A cylindrical sample of aluminum alloy gradient composites reinforced by self-crystallized Si particles and NiAl

3

particles was prepared by electromagnetic centrifugal casting with Al-14 Si-6 Ni alloy as blank.The outer layer of the composites prepared contains high volume fraction primary Si phase and NiAl

3

particles to form an enhanced layer.The inner layer contains a small amount of Si particles and a large number of pores and oxidized slag inclusion.The hardness and friction coefficient of the composites were further determined

including stratification observation of the microstructure of the composites with different process parameters

detection of the macroscopic hardness of each layer and the friction coefficient between the sample and Si

3

N

4

under the same load condition.The results reveal that as a result of existence of a large number of NiAl

3

and primary Si at the outer layer of the composites

the hardness of outer layer is greater than that of inner layer of the composites at different process parameters.In particular

by comparing micro-indentation

it is found that NiAl

3

can improve the macroscopic hardness of primary Si.At the same time

through the quantitative analysis of friction coefficient of each layer

it is found that the friction coefficient between aluminum alloy and Si

3

N

4

can be reduced by Si particles and NiAl

3

particles.