| In this thesis, AZ91D magnesium matrix compsites reinforced with a low cost crystallized alumina silicate short fibers was fabricated with even microstructures and without casting defects by liquid squeeze casting. The Influences of fiber content on creep behaviors of Al2O3-SiO2/AZ91D composites were investigated.The experimental results indicate that the Al2O3-SiO2/AZ91D composites have better high temperature anti-creep capability than AZ91D magnesium alloy.For variable temperature and external load,the Al2O3-SiO2/AZ91D composites have analogical creep deformation principles.The Al2O3-SiO2/AZ91D composites shown more poor creep properties with the increase of temperature and stress,and higher creep properties with the increase of fiber contents. Temperature played the more important role on Al2O3-SiO2/AZ91D magnesium matrix composites.It is belived that the creep mechanism of Al2O3-SiO2/AZ91D composites is slippage of dislocations and grain boundary through analysis of creep exponent of Al2O3-SiO2/AZ91D composites. With the increase of fiber content, creep activation energy and creep threshold stress increase gradually. With the increase of temperature, creep threshold stress decreases gradually .Some fibers felling off from the matrix during creep. Most of fibers fractured while Al2O3-SiO2/AZ91D composites failured, but fibers were not found to be pulled out form Al2O3-SiO2/AZ91D composites. With increase of fiber content, creep resistance of Al2O3-SiO2/AZ91D composites composite increased,and the creep properties were improved greatly.
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