Preparation Of In-situ TiC·Al₂O₃/7075Al Matrix Composites

For the issue that the Al-Ti-C system form long strip immediate products during in situ reaction,CuO was added in the Al-Ti-C reaction system to constitute Al-Ti-C-CuO complex system which process in situ reaction in 7075 alloy melt.The in situ TiC·Al2O3/7075 aluminum matrix composites are prepared by near-liquidus casting process.In order to obtain tiny and uniform particles,the ratio of reaction,preheating temperature and the content of diluent were adjusted to decrease or refine the intermediate products.By using OM(optical microscope),DSC(differential scanning calorimetry),XRD(X-Ray Diffraction),and SEM(scanning electron microscope) in situ reaction process of Al-Ti-C-CuO complex system was deeply analyzed and the suitable parameters of fabrication processes of TiC?Al2O3/7075 aluminum matrix composites was determined.The thermodynamic analysis indicated that after the addition of CuO in Al-Ti-C reaction system,the reaction heat of Al and CuO provide more heat for Al-Ti-C system which will lead to promote the completely process of reaction system of this paper and will contribute to resolvement of Al3 Ti and production of TiC particles.When the preheating temperature of melt is 1000℃,Al:Ti:C:CuO=4.8:1:1.2:1(molar ratio),the generation of Al3 Ti is more less and the distribution of TiC and Al2O3 particles in the matrix are more uniform and the isometric organizations are increased.The comparison of two kind of composites prepared by Al-Ti-C system and Al-Ti-C-CuO system showed that the generation of Al3 Ti in Al-Ti-C-CuO system was more less and the alloy’s microstructure refined much better and the average grain size are about 25 μm.