Preparation and characterization of aluminum matrix composites based on Al-WO ₃ system

The (WAl ₁₂ + Al ₂O ₃)/Al composites were fabricated by powder metallurgy based on the in situ reaction between WO ₃ and Al powders in this paper. The microstructure and properties of the composite were investigated and the reaction mechanism was determined. The produced reinforcements including WAl ₁₂p and W precipitated Al ₂O ₃ clusters are distributed mainly by a network in the matrix, where the majority of reinforcements lied within the wall of network with a thickness of 5-10 μm, and while a small part of fine reinforcements in the interior of network. The results show that the WAl ₁₂ and Al ₂O ₃ clusters were formed by the reaction between WO ₃ and Al during the sintering process, and WAl ₁₂ has the orientation relationship with Al: [1 1 0] _Al[0 0 1] _WAl12, (1 -1 1) _Al(3 1 0) _WAl12, meanwhile, nanosized W precipitates was formed and embedded in Al ₂O ₃ particles. The mechanical properties of (WAl ₁₂ + Al ₂O ₃)/Al composites were improved as compared with Al matrix due to the introduction of reinforcement particles, which is due to Orowan strengthening mechanism of reinforcements. The WAl ₁₂ and Al ₂O ₃ containing nanosized W precipitates reinforcement phases possess an outstanding hybrid effect on the mechanical properties of the composite, including strength and plasticity.