Ti-48Al-6Nb-xSi（x=0.5

1 and 2）TiAl alloy ingots with different silicon addition were prepared

and then heat treated at different temperature

respectively.The effects of heat treatment temperature on the structure and mechanical properties of the Ti-48Al-6Nb-xSi alloy ingots were analyzed.The results show that the structure of the as-cast ingots are refind after heat treatment and the equiaxed grain area inthe ingots is increased and the width of the column grains become smaller with the increasing of the heat treatment temperature.Meanwhile

the lamellar structure become thinner.The microstructure of the alloy is changed from column grain structure to equiaxed grain structure with increasing of heat treatment temperature.And the amount of Ti

5

Si

3

phase is reduced

while its distribution become more uniform.The microhardness of Ti-48Al-6Nb-xSi alloys is increased with silicon content increasing and decreased with increasing of the heat treatment temperature.