Al-TiO2-C系XD合成铝基复合材料的反应机理及拉伸性能

The reaction mechanism of aluminum matrix composites fabricated by XD method in Al-TiO2-C reaction system was investigated. The thermal analysis indicates that the reactions in Al-TiO2-C system are spontaneous and exothermic. The Gibbs form free energy of the α-Al2O3 is the lowest and it is the steadiest among the possible reaction products. The TiC phase forms previously to the Al4C3 phase at the temperature of higher than 500K. The Al4C3phase can not occur in the combustion results. The experiment results show when the C/TiO2 mole ratio is zero, the reinforcements are composed of α-Al2O3 particulates and Al3Ti rods. The α-Al2O3 particulates are assemble at grain interface and the Al3Ti rods distribute uniformly in the matrix. With increasing of C/TiO2 mole ratio, the active Ti atoms which are produced from the reaction of Al and TiO2 would previous react with C atoms to form the TiC particulates and then the Al3Ti are restrained. When the C/TiO2 mole ratio is up to one, the Al3Ti rods almost disappear and the Al4C3 phase do not occur in the composites. At the same time, the ultimate tensile strength and elongation of the composites increase from 273.4MPa and 3% to 350.7MPa and 6% respectively.