Recrystallization and grain growth of sintered aluminium powder alloys studied by using a nuclear non-destructive technique

Positron lifetimes have been measured for cold rolled (∼90%) sintered aluminium powder (SAP) alloys with different amounts of Al2O3 content and for similar samples annealed at temperatures ranging from 623 to 873 K (recrystallization region). The same measurements were performed on aluminium (99.5%) for comparison. In the present study, calculations of the average lifetime τav and τbulk and the trapping rate k were deduced from the lifetime parameters in the free and trapped states τ1, τ2 and their intensities I1, I2. The present lifetime parameters were used to explain the effect of amount of alumina on recrystallization and grain growth of SAP alloys. The trapping locations are suggested to be at grain boundaries since increasing of alumina increases the grain size and varies the interparticle spacing.