Preparation Of Al₂O_3p/Al-Cu Matrix Semi-solid Billet

In-situ reactive Near-liquidus Technology is combined In-situ reactive and near-liquidus method. It is a new method to produce Semi-solid billet. The use of composite alloy phase diagram, Particles will be generated at the completion of alloy melt, then casting in the Near-liqudus temperature. to get the requirements of semi-solid billets of Thixoforming process. Its advantage lies in the surface of the particles in-situ non-polluting, uniformly distributed In the matrix, Dendritic structure is controlled at Near-liquidus casting temperature and some small rose-like organizations are formed,and process is simple, efficiency of the production is high, the multi-alloy of application is varieties.In this paper, in-situ reactive near liquidus casting method is used to prepared the Semi-solid billet of Al₂O₃P/Al-Cu matrix Al₂O₃P/Al-Cu-Si matrix. The influence of process parameters are studies, At the same time, the optical microscopy, transmission electron microscopy, X-ray diffraction is used to research the Semi-solid billet of Al₂O₃P/Al-Cu matrix microstructure. The conclusions can be received through experiments and theoretical analysis:Adiabatic temperature of reaction decreased from low volume, high pre-heating temperature side to the high diluent volume, low pre-heating temperature side; the use of magnesium ignition as the agents , with the reduction in the amount of magnesium, the reaction induction time Extended;When the particle content of in-situ Al₂O₃ come to 5.3wt%, melt temperature 850℃, the quality of block components Content of Al: CuO = 1:1 and then adding the total mass of the preform 1/1200( Mg powder )when the reaction was carried out smoothly and does'nt explode. The Semi-solid billets of Al₂O₃P/Al-Cu-Si reactant ratio for Al: CuO: SiO₂ = 2:3:2, initiator of adding Mg is 1/300 of preform, when the aluminum melt temperature reached 950℃, the reaction is exhaustive . The particle of in-situ Al₂O₃ is fine and diameter is less than 0.5μm, dispersing in the matrix and the interface is clean, pollution-free; the Al₂O₃ particles is increased with the in-situ reaction with the addition of materials to generate, but at the same time generate the alloy Elements of copper also increased significantly, with increased content, CuAl₂ was distributed like network around in the grain.