AZ91 Mg metal matrix composites have been prepared by the squeezing-infiltration method

in which preform was fabricated with crystallized alumina silicate short fibers as reinforcement and aluminum phosphate as binder

and by combining dry method with green method. The casting defects and microstructure in Mg metal matrix composites have been described by means of OM （optical microscope） and SEM（scanning electron microscope）. The experimental results indicate that neural aluminum phosphate solution is one of the best binders for fabricating alumina silicate fibers （Al

2

O

3

-SiO

2

/AZ91） reinforced Mg metal matrix composites. The structural shrinkage porosity in the MMCs can be effectively reduced

or even be eliminated by complex squeezing-infiltration process.