The recovery behavior of quenched-in defects in TiAl and Ti3Al alloys has been studied by the positron annihilation technique. It is shown that in a fully annealed sample there exists a certain number of grain boundaries in TiA1 alloy

and during quenching from high temperature

quite a lot of secondary defects such as vacancy clusters and vacancy-impurity complexes are produced. Because of the decomposition and transportation of defect complexes

the vacancy clusters aggregate further in the range of 300 to 600℃