Positron annihilation lifetime spectroscopy (PALS) is one of the nuclear techniques used in material science. (PALT) measurements are used to study the behaviour of the defect concentration in a set of AlSi10.9Mg0.17Sr0.06 alloys. It has been shown that positrons can become trapped at imperfect locations in solids, and that their mean lifetime can be influenced by changes in the concentration of such defects. No changes have been observed in the mean lifetime values following saturation of the defect concentration. The mean lifetime and trapping rates were studied for samples deformed up to 34.9 %. The concentrations of defects range vary from 5.194x1015 to 1.934x1018 cm-3 for thickness reductions of 2.2 to 34.9 %. The range of the dislocation density varies from 1.465x 108 to 5.454x1010 cm/cm3 over the same range of deformations.