Positron annihilation measurements were made of the sub-surface zones in Al and Al-alloy which was subjected to indentation by a small steel ball or to blasting with SiC particles. Measurements of Doppler broadening of the annihilation line, and of positron lifetimes, permitted the depth-profiles of open-volume defects introduced by indentation or blasting to be obtained. Coincidence of the von Mises yield criterion, with the onset of an increase in the defect concentration at a certain depth, was detected. It was established that the defects which were created in pure Al and in Al-alloy, as detected by positrons, were different. However, the type of introduced defect did not change with depth. The positron lifetime measurements indicated the presence of vacancy clusters in samples which were exposed to blasting. The vacancy clusters which were created in the Al-alloy were larger than those in pure Al.

Defect Depth Profiling after Sphere Indentation and Blasting in Aluminum and Aluminum Alloy Detected by Positron Annihilation. E.Dryzek: Journal of Materials Science, 2003, 38[18], 3755-63