Abstract:SiC particles reinforced aluminum matrix composites were prepared by hot isostatic?pressing?(HIP). Microstructures and mechanical properties of the composites were studied. The fracture morphology and mechanism were analyzed and the thermal expansion coefficient of composites was also measured. The results show that the SiC particles in the composites agglomerate and form a hard SiC?skeleton after hot isostatic pressing. The tensile strength of 20%SiCp/6061Al (volume percent) composites reaches 304 MPa, while the tensile strength of 20%SiCp/2024Al (volume percent) composites reaches 276 MPa. The tensile strength of both composites reaches or exceeds the level of other preparation methods. The fracture mechanism of composites is the ductile fracture of the matrix, the cleavage fracture of SiC particles and the interface stripping between SiC and matrix. The thermal expansion coefficients of composites are compared with Turner and Kerner theory values. It shows that the numerical value of Turner model is closer to the experimental value.