Abstract: The synthesis of TiN and Al2O3 by in situ injection of reactive nitrogen gas into molten Al alloys has been evaluated over the temperature range from 1000 to 1600℃. It is shown that TiN and Al2O3 can be formed in melt with nitrogen and surplus oxygen (in vacuum room of the induction furnace) as the reactive gases over 1000℃. Up to 2.1 wt pct Al2O3 and 5.2 wt pct of TiN in situ phases in an Al alloy has been formed in a range of size from 0.8 to 5 μm. The formation mechanism of TiN and Al2O3 is discussed in this paper.