National Engineering Research Center of Near-net-shape Forming for Metallic Materials, South China University of Technology, Guangzhou, China
Department of Mechanical Engineering, Imperial College London, Exhibition Road, London SW7 2AZ, UK
Particulate-reinforced aluminum matrix composites produced by stirring casting method exhibit many advantages and are usually used in practical industries. The particulate flow and distribution during the stirring have significant effects on composite casting properties and performances. In this investigation, to study the effect of stirring parameters on particulate distribution, an experimental quenching apparatus was designed, and then A356/50μmSiCp prepared with different stirring speeds and positions were carried out. The particulate fractions at different locations of the prepared composites were quantitatively measured with micro-image analysis, and the charts of particulate distribution along axial directions were summarized and analyzed. Based on liquid-solid multiphase flow theory and multiple rotating reference frame models, a mathematical model of particulate-reinforced aluminum matrix composites stirring process established with consideration of relative flow between liquid and solid particle phases was applied to the experimental composite preparation. By comparing the simulation and experimental results, the effect of stirring condition on the composite slurry and particulate flow as well as the final particulate distribution were analyzed. The comparison shows that the simulated particle distribution exhibits well agreement with the experiment, indicating the validity and exactitude of the established model and method for actual composite stirring preparation. The study shows that low position of impeller would force more particles at the bottom region to flow with composite slurry, improving the particle distribution, and that high stirring speed can cause strong centrifugal force and radial flow of both composite slurry and particles, decreasing the particle uniformity in the composites.