Vacancy-type defects in amorphous and nanocrystalline Al alloys: Variation with preparation route and processing

Positron annihilation spectroscopy was performed in order to study the influence of preparation route and processing on atomic free volumes in amorphous and nanocrystalline aluminium alloys. In melt-spun amorphous Al88Y7Fe5, structural free volumes smaller than a lattice vacancy are predominant, whereas in amorphous Al92Sm8 prepared by repeated cold rolling larger free volumes occur. In the early stages of nanocrystallization of Al88Y7Fe5, an indication of Y enrichment at interfacial free volumes in the growth front of the Al nanocrystallites is found.