High-performance Al-1.5 wt% Si-Al2O3 composite by vortex-free high-speed stir casting

Abstract

Abstract Rapidly achieving uniform distribution of ceramic particles without air entrapment is a huge challenge for stir-cast Al matrix-ceramic composite. To overcome this challenge, vortex-free high-speed stir casting (VFHSC) of Al-1.5 wt% Si-Al2O3 (3 μm) composite is investigated. The microstructure and composition of ingot are examined by SEM, XRD, TEM and HRTEM. The porosity of composite can be reduced to about 0.036 vol% in vortex-free mode under 2200∼2700 r/min high-speed electromagnetic-mechanical stirring by removing air entrapment. The uniform distribution of Al2O3 particles in the Al-1.5 wt% Si slurry can be achieved rapidly with the help of tilt blades in crucible and can be maintained during casting in metal mold. Moreover, the VFHSC Al-1.5 wt% Si-Al2O3 (3 μm) composite has perfect performance. The ultimate tensile strength of Al-1.5 wt% Si matrix is improved 73.6 %, the hardness is increased from 60 to 81 BHN and the wear rate is decreased 92.6 % by 5 vol% Al2O3 particles. This work disposes of the long-existed problem of stir casting and presents a practical stir-casting mode for Al-Al2O3 composite.