Effect Of Powder Metallurgy Processes By High Energy Ball Milling On The Microstructure And Properties Of Aluminum Matrix Composites

The powder fabricating process for particle reinforced Aluminum matrix composites was optimized by orthogonal and single experiment. The results indicate that three procedure factors, velocity, time for milling and the amount of process control agent (PCA), are important for particle size and properties. The optimal process parameters have been proposed. They are 280rmp and 15h with 4 %( wt) PCA. Based on this, two key problems were investigated further in this paper.First, choosing cheaper industrial alumina(γ-Al₂O₃) as reinforcement,γ-Al₂O₃/Al composites was fabricated successfully by powder metallurgy. Thisγ-Al₂O₃/Al composites was treated by water-logging method. Experiment showed that its hardness was nearly 4.2 times higher than before water-logging treatment, reached to 103.8HB, and its wear resistance increased about twice. Mechanism analyses indicated that the properties, improvement was caused by several factors which worked together. There were densification, falling down of system energy, improvement of interface, and dispersion of reinforcement. At last, a new reinforce model, The Second Reinforce Model, was put forward.Second, SiCp/Al composites with vary rare earth oxide (CeO₂) was fabricated by means of powder metallurgy successfully. Its properties and microstructure were studied by equipments and the influence of RE content was analyzed. The results show that RE can improve the wearing performance and hardness of the composite. The optimal amount of RE is 0.4 %( wt), overmuch added will induce a bad result. Mechanism analyses show that the improvement was caused by the addition of CeO₂; it can restrain the interface reaction of SiCp/Al.