Preparation Of In-situ TiC·Al₂O₃/Aluminum Matrix Composites

In-situ TiC·Al₂O₃/aluminum matrix composites were prepared by Al-Ti-C-CuO reaction system and in-situ near liquidus casting method for the purpose of reducing mesophase Al₃ Ti which easily formed by process of in situ reaction of Al-Ti-C system.the thermodynamic feasibility of the reaction system were analyzed by the thermodynamic test and calculation.The morphology,phase and size of the in situ reaction products of Al-Ti-C-CuO system were analyzed by optical microscopy,X-ray diffraction,scanning electron microscopy and energy dispersive spectroscopy.The reaction process of Al-Ti-C-CuO system in aluminum alloy melt,strengthening mechanism of reaction product,the influence of preparation parameters on the reaction process of Al-Ti-C-CuO system and the influence on the microstructure of the prepared aluminum alloy composites was systematically analyzed to determind the optimized parameters for preparing in situ TiC·Al₂O₃/Al based composites under laboratory conditions.The results are as follows;In-situ reaction process of Al-Ti-C-CuO system: Al powder quickly melted and wrapped Ti,C and CuO powder and reacted with Ti to produce Al₃ Ti by releaseing heat,at the same time,Al₂O₃ particles formed by Al and CuO reaction and releaseed a large amount of heat which improve the temperature of the melt and the wetting of the C and aluminum melt and promote the dissolution of Al₃ Ti formed by self-propagating reaction,the reactin of Ti and C generate TiC particles.The TiC particles formed by in-situ reaction of Al-Ti-C-CuO system are about 1?m in diameter,mostly spherical,Al₂O₃ particles are regular spherical,about 1?m in diameter,and the size of Al₃ Ti is small.The strengthening mechanism of TiC·Al₂O₃/aluminum matrix composites is fine grain strengthening and dispersion strengthening.when 1000 ? for the preheating temperature,10 MPa for the reactant molding pressure,40% for diluent Al accounts,Al:Ti:C:CuO = 2.5:1:1.2:0.5 for reactant molar ratio,Add 0.6% La₂O₃ of prefabricated mass,The TiC and Al₂O₃ particles formed by in-situ reaction of Al-Ti-C-CuO system are well dispersed and Al₃ Ti is not obsevated.in-situ TiC·Al₂O₃/aluminum matrix composites are homogeneous and have a small grain size and 32.8HBW for its hardness?16.8HBW for 6063 aluminum alloy hardness?.