Berlin 2018 – wissenschaftliches Programm
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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur
KFM 24: Spectroscopy and Microscopy II with Positrons
KFM 24.4: Vortrag
Donnerstag, 15. März 2018, 10:40–11:00, E 124
Thermal vacancies in highly diluted Al-In alloy — •Mohamed Elsayed1,2 and Reinhard Krause-Rehberg1 — 1Institut für Physik, Martin-Luther Universität, Halle — 2Physics Department, Minia University, Egypt
Positron annihilation lifetime spectroscopy (PALS) is applied to study the point defects generated in aluminum indium alloy upon quenching. Al alloy having 0.005-0.025 at % In is used in this study. The samples were homogenized for 2 h in the temperature range 320-620 °C, then rapidly quenched in ice water. They were immediately measured at room temperature (RT) by positron lifetime spectroscopy. The samples were isochronally annealed in the temperature range up to 327 °C in steps of 10 °C, they cooled down after each annealing step to RT and measured by PALS. It is found that the average positron lifetime increases to 240 ps with increasing quenching temperature up to 470 °C and it decreases slightly with further increase of the quenching temperature. A reference pure aluminum (99.9995) samples is quenched at different temperature to show the influence of the alloying element (In) on the vacancy formation. An average lifetime of 170, very close to the bulk value (158 ps), is obtained, indicating the role played by In on the vacancy formation. A defect-related lifetime of 247 ps is obtained in all quenched samples immediately after quenching. This lifetime corresponds mostly to vacancy-In complexes. The defect-related lifetime is found to decrease with increasing annealing temperature up to 127 °C reaching 225 ps, then it increases reaching 280 ps, corresponding to divacancy.