The surface of AZ91 alloy engine cylinder was modified by surface plasma cladding.The microstructure and phase constituent of AZ91 alloy substrate

TiB

2

-Al

2

O

3

and varied Al∶（TiB

2

-Al

2

O

3

）compound modified layer were analyzed

and the hardness

wear resistance and corrosion resistance of the modified layer were investigated.The results show that with the increase of distance from the surface of the modified layer

the micro-hardness of the modified layer is decreased gradually

however

the microhardness of the modified layer is the higher than that of AZ91 alloy substrate.The micro-hardness of the modified layer is decreased gradually with the increase of Al content

while the micro-hardness of TiB

2

-Al

2

O

3

modified layer has the maximum value.With prolonging wear time

the wear weight loss of the substrate and modified layer are increased gradually

and the wear resistance modified layer with w（Al）∶w（TiB

2

-Al

2

O

3

）=1∶2exhibits desirable.The corrosion resistance of the modified layer is improved compared with AZ91 alloy substrate

and the modified layer with w（Al）∶w（TiB

2

-Al

2

O

3

）=1∶2has the satisfied corrosion resistance.