In the present study a Ti-B2 containing metal matrix composite has been made by mixing of two molten master alloys, Al8%Ti and Al- 4%B. The weight ratio of Ti:B was selected in an appropriate portion to ensure the formation of TiB2 particles in aluminium matrix. The Al-8%Ti and Al4%B master alloys were made by K2TiF6 and KBF4 salts in an induction furnace. The mechanism of formation of the TiB2 particles was studied by an optical microscope equipped with a Hot Stage, providing direct observation of phase transformation by recording real images. The study of phase transformation of solidified specimen microstructures was made by a scanning electron microscope coupled with EDAX analyzer. The results obtained from Hot Stage studies indicated that the boron atoms migrate easily towards TiA13 particles to produce very fine TiB2 particles on the interface of TiAl3 particles and matrix alloy. Small atomic radius of boron and the ease of its diffusion may cause the readily access of boron on the interface and also formation of agglomerated TiB2 particles, as a result of exothermic reaction of TiB2 formation. The microstructural studies of the real-time observation showed that due to the high mobility of TiB2 particles and their easily separation from TiAl3 particles, the growth rate of these particles is high and penetration of boron into the TiA13 particles leads to the replacement of agglomerated TiB2 particles (in a ring shaped) with large TiAl3 particles.
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