Positron lifetime measurements were performed at room temperature, before and after the isochronal annealing of cylindrical fatigue specimens and round slabs of AISI316L austenitic stainless steel which were deformed in compression. The annealing experiments were evaluated in terms of vacancy migration, and grain-boundary or dislocation sinks. The model assumed the existence of spherical grains having an homogeneous initial distribution of vacancies. A vacancy migration enthalpy of 0.9eV was estimated. It was concluded that positron trapping at dislocation lines did not significantly contribute to positron lifetime measurements at room temperature, and that single vacancies were the predominant positron traps. Positron annihilation depth-profiling of cross-sectional areas which were prepared from machined specimens, using a positron microprobe with 10µm spatial resolution, showed that the machining of cylindrical specimens created vacancies at up to 5mm below the surface.

Positron Annihilation Studies on the Migration of Deformation-Induced Vacancies in Stainless Steel AISI316L. U.Holzwarth, A.Barbieri, S.Hansen-Ilzhöfer, P.Schaaff, M.Haaks: Applied Physics A, 2001, 73[4], 467-75