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Positron lifetime measurements were carried out at room temperatures before and after isochronous annealing of cylindrical, machined fatigue specimens and of round slabs of austenitic stainless steel AISI 316 L deformed in compression. Annealing experiments are evaluated in terms of vacancy migration and sinking to grain boundaries and dislocations. The model assumes spherical grains with a homogeneous initial distribution of vacancies. A vacancy migration enthalpy of H(M/V) = (0.9+/-0.15) eV was found. It is concluded that positron trapping at dislocation lines does not significantly contribute to positron lifetime measurements at room temperature and that single vacancies are the dominating positron traps. Positron annihilation depth profiling on cross-sectional areas prepared from machined specimens using a positron microprobe with a 10 micro-m spatial resolution shows that machining of cylindrical specimens creates vacancies up to 5 mm below the surface.

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Authors: HOLZWARTH U, JRC, Ispra (IT);BARBIERI A, JRC, Ispra (IT);HANSEN-ILZHÖFER S, JRC, Ispra (IT);SCHAAFF P, Max-Planck-Institut fur Metallforschung, Stuttgart (DE);HAAKS M, Institut fur Strahlen- und Kerphysik der Universitat Bonn (DE)
Bibliographic Reference: An article published in: Applied Physics A, Vol.73 (2001), pp.467-475
Record Number: 200114061 / Last updated on: 2001-11-23
Original language: en
Available languages: en