IN-SITU PREPARATION OF TIB2 REINFORCED AL BASE COMPOSITE

In situ formation of Al-TiB2 metal matrix composite has been successfu lly fabricated through an exothermic reaction process. The base alloy used in the present investigation was Al-4 wt% Cu. It was first melted at 850 degrees C. After that, two types of salts, namely, K2TiF6 and KBF4 were added into the molten Al alloy by stirring. An exothermic re action between the two salts and molten Al took place to form in situ TiB2 particulates in the molten Al alloy. The exothermic reaction peri od was varied from a minimum 5 min to a maximum 35 min to investigate the relationship between the degree of reaction, the growth behaviour and the microstructures of TiB2. After the reaction, the composite was cast into rods of 25 mm diameter. Both X-ray diffraction measurement and scanning electron microscope analysis revealed the formation of Ti B2. The amount of TiB2 particulates increased when the exothermic reac tion period was prolonged. Its microstructure was examined under optic al and scanning electron microscopes.