Low volume fraction of short mullite fibers reinforced aluminum/silicon （M124F） alloys were prepared by the squeezing-casting process.The hardness

thermal expansion coefficient and the tensile strength of the composites were investigated from room temperature to 400 ℃.It is found that the tensile strength of the composites at room temperature is somewhat inferior to that of the M124F alloy.However

mullite fibers exert a beneficial effect on improving the tensile strength of M124F alloy at higher temperatures by more than 15% compared with other fibre reinforced composites.The fracture morphology of the composites specimens is observed with SEM to show the failure mechanism of the composite

where micro-crack is propagated in the interface between reinforced fibre and the matrix.