中国有色金属学报(英文版)
Transactions of Nonferrous Metals Society of China
| Vol. 17 No. 3 June 2007 |
（1. Department of Materials Science and Engineering,
Nanjing University of Science and Technology, Nanjing 210094, China;
2. Department of Materials Science and Engineering, Southeast University,
Nanjing 210096, China）
Abstract:The formation of aluminum matrix composites fabricated by exothermic dispersion reaction in Al-TiO2-B2O3 system was investigated. The thermal analysis results show that the reactions are spontaneous and exothermic. The Gibbs free energy of α-Al2O3 is the lowest among all the combustion products, followed by TiB2 and Al3Ti. It is noted that when the B2O3/TiO2 mole ratio is below 1, the reaction products are composed of particle-like α-Al2O3, TiB2 and rod-like Al3Ti. The α-Al2O3 crystallites, resulting from the reaction between Al and TiO2 or B2O3, are segregated at the grain boundaries due to a lower wettability with the matrix. SEM micrographs show that rod-like Al3Ti phase distributes uniformly in the matrix. When the B2O3/TiO2 mole ratio is around 1, the Al3Ti phase almost disappears in the composites, and the distribution of α-Al2O3 particulates is improved evidently.
Key words: aluminum matrix composite; reaction mechanism; mole ratio; exothermic dispersion reaction
