Effects of yttrium on the microstructure and high temperature oxidation behavior of arc melted Ti-45 Al-6 Nb alloys were investigated. The results show that the obtained Ti-45 Al-6 Nb alloys with different yttrium are mainly composed of γ+α

2

lamellar

B

2

precipitate and a small amount of Y

2

O

3

. Addition of trace yttrium in the alloy can be ingored for influence on the phase composition of the alloys

however

it can significantly refine α

2

+γ lamellar structure. High temperature oxidation results show that addition of trace yttrium in Ti-45 Al-6 Nb alloys can significantly improve the oxidation resistance

especially for the alloy with yttrium concentration of 0.3%. The Ti-45 Al-6 Nb-0.3 Y alloy has an oxidation rate constant of 3.26×10

-2

mg

2

/（cm

4

·h） at 1 000 ℃ in air

which is account for 41.3% and 26.1% of the alloys with yttrium concentrations of 0.1% and 0.9%

respectively

and about 1 order of magnitude lower than that of the alloy without yttrium addition.