  We present the results of lifetime positron annihilation spectroscopy (PALS)
for the alloys Fe21Ga and Fe22.4Ga, whose defect structure is connected with
annealing from 20 to 1000C along the phase diagram of Fe21Ga and Fe22.4Ga, at
the L12-A2 transitions and in the sub-lattice of the D03 phase. In frames of
the standard trapping model, we estimate the positron annihilation parameters
for the bulk metal and for the different thermal vacancies herein. Also we
define concentrations of these vacancy defects, which may be helpful for
explanation of the physical properties of Ge-Ga alloys, including giant
softening and extremal $\lambda_{100}$ at the given inter-metallic composition.
