DISPERSOID AND SiC PARTICULATE STRENGTHENED Al COMPOSITES II. PROPERTIES AND FRACTURE BEHAVIOUR

The tenisle tests and fracture surface analyses on the Al_4C_3. Al_2O_3 dispersoids and SiC particulate strengthened aluminum composites fabricated by mechanical alloying were carried out, as well as elastic modulus and CTE of the composites were measured.It was indicated that the strength of SiC_p/ Al composites is obviously improved due to the formation of Al_4C_3 and Al_2O_3 dispersoids, and increases with increasing C content or oxidation time of aluminum powder. The elevated temperature strength of Al_4C_3 dispersoid and SiC particulate reinforced aluminum composite is superior to that of SiC whisker reinforced 2024Al composite. The elastic modulus of Al_4C_3/ Al composite is raised due to the addition of SiC particulates, and CTE is reduced further.The fracture surfaces of the composites display mixture type of large dimples and fine dimples. The amount of cracked SiC particulates on tensile fracture surfaces of the compsites increases with increasing the strength of compsite matrix.