In situ synthesis of TiB2/Mg composite by self-propagating high-temperature synthesis reaction of the Al-Ti-B system in molten magnesium

The synthesis of in situ formed TiB2/Mg composite utilizing the self-propagating high-temperature synthesis (SHS) reaction that occurred between the molten magnesium and green preforms consisting of Al, Ti and B powders was investigated. The result shows that it is feasible that the smelting temperature of the magnesium matrix alloy is selected at 860degreesC, which is slightly higher than the exothermic reaction temperature of 852degreesC on the DTA curve, prepared for the SHS reaction in the Al-Ti-B system. An as-cast microstructure of the composite reveals a relatively uniform distribution of TiB2 particulates with hexagonal or rectangular size of similar to2.0 mum. Furthermore, an analysis of the powders extracted from the TiB2/Mg composite confirms that a small amount of blocky TiAl3 phase is also present in the composite. (C) 2004 Elsevier B.V. All rights reserved.