Abstract
The behaviour of positron in grain boundaries, is characterized by their bulk diffusibility D, their bulk (free) lifetime tau sub f , and their trapped lifetime tau sub t ( tau sub t > tau sub f ). Al-Mg sub x samples (x=0-1.4 at%) have been homogenized at 573 K for 12 hours. The obtained mean lifetime results showed a good fitting with Sigmodel giving tau sub t = 180.664 ps and tau sub f = 163.9 ps. The mean lifetime was found to vary exponentially with degree of deformation. XRD study showed that preferred orientation occurred at degree of deformation > 32%, whereas the peak intensity then increases with sample deformation. Recrystallization is also followed by XRD. Peak intensities decrease with increasing annealing time which is attributed to recrystallization, but it does not completely reverse to the origin condition. For all cases, no peaks of Mg were revealed indicating the positron annihilation as a sensitive technique for detecting low concentrations in alloys.