Positron Annihilation Study of Precipitation in the 2219 Al-Cu Alloy

Abstract

A positron annihilation study of the 2219 Al‐Cu alloy shows the existence of at least three families of positron traps: a) vacancies in pure Al around GP1 zones, b) vacancies inside GP2 zones, c) dislocations in the misfit region around semicoherent and incoherent precipitates. The decomposition of the alloy, obtained by isothermal ageing, is observed by measuring the variations of the fraction of positrons trapped in each family. The analysis of the data gives quantitative information on the dissolution of GP1 zones and on the transformation of GP2 zones in semicoherent precipitates Θ′ (CuAl2).