Research On Microstructure And Properties Of Hybrid Particle Reinforced Aluminum Matrix Composites Prepared By Powder Metallurgy

Particle reinforced aluminum matrix composites have a series of excellent properties such as high stiffness, high wear resistance, excellent thermal stability, and get important applications in the automotive, aerospace, electronics and other fields.While micron/nano particle hybrid reinforced aluminum matrix composites have much better properties and have been the most important part of the research. In this study,micron/nano particle reinforced aluminum matrix composites were prepared by powder metallurgy. At the same time, the mixed powder pressing process and sintering process were analyzed and optimized. On this basis, Si C particle reinforced aluminum matrix composites, Ti B2 particles reinforced aluminum matrix composites, Si C(micron)-Ti B2(nanometer) two phase hybrid reinforced aluminum matrix composites were prepared,and the density and hardness analysis, XRD analysis, tensile test, SEM and other means were used to analyzed the microstructure and properties of particle reinforced aluminum matrix composites prepared.The relative density of the particulate reinforced aluminum matrix composites increased with the increase of cold pressure. When the cold pressure increased to750 MPa, the relative density of the 5%Si Cp/Al-Si composites reached 93.68%. To further increase the pressure cannot significantly improve the density. And the porosity of the composites decreased with the increase of sintering temperature. The optimum sintering process is sintered at 640 degrees Celsius for 40 min, and the relative density is above 92%.For both Si C or Ti B2 single phase reinforced aluminum matrix composites and dual particle hybrid reinforced aluminum matrix composites, the increase of volume fraction of reinforced particles result in the increase of the hardness, tensile strength and other properties of the composites. The best content of reinforcing particles for Si C, Ti B2, Si C-Ti B2 reinforced aluminum matrix composites is 5%, 1.5% and5%Si C-1.5%Ti B2, respectively.Compared to Si C, or Ti B2 single phase reinforced aluminum matrix composites,hybrid reinforced aluminum matrix composites had better properties, which mainly reflected in the hardness and the tensile strength. For 5%Si C-0.5%Ti B2 hybrid reinforced aluminum matrix composites, the hardness and tensile strength are 53.39 and 158 MPa, respectively.The analysis of the fracture morphology of particles reinforced aluminum matrix composites showed that the fracture mechanism as a mixed fracture mechanism.When the interface between the particles and matrix was in good condition, the main fracture mechanism of particle reinforced aluminum matrix composites was ductile fracture. However the interface was poor, the fracture mechanism of the matrix composites was matrix plastic fracture and the particle debonding from the matrix interface.