Effect of Deformation on Positron Annihilation in Decomposing Copper Alloys |
| V.S. Mikhalenkov Institute of Metal Physics, Ukrainian Academy of Sciences, 262680 Kiev-142, Ukraine P. Hautojärvi and A. Vehanen Laboratory of Physics, Helsinki University of Technology, 02150 Εspaoo-15, Finland |
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| Positron lifetime spectra were measured in the quenched or slowly cooled Cu-3.93 at.% Ag alloy, subjected to subsequent cold rolling, as a function of isochronal annealing temperature. The results were compared with the formerly obtained data for quenched, but not deformed, Cu-Ag alloy and for deformed Cu-Ge solid solution. All lifetime spectra, after background and source corrections, are single exponential with the lifetimes which exceed those in well-annealed Cu solid solutions. This gives evidence to positron annihilation from a trapped state. One-component spectra may then testify to existence of a set of different traps with too weak distinction in the individual positron lifetime to be resolved as separate components. At low annealing temperatures the stage arisen from continuous decomposition is not revealed, being masked by the removal of deformation defects. The stages of discontinuous decomposition and of subsequent precipitates coagulation turn out to depend on the sample history. The role of deformation defects in the decomposition of supersaturated solid solutions is attempted to be accounted for in a wide range of annealing temperatures. |
| DOI: 10.12693/APhysPolA.88.199 PACS numbers: 61.66.Dk, 61.72.Ff, 78.70.Bj, 81.30.Mh |