Regensburg 2010 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 14: Diffusion and Point Defects III

MM 14.3: Talk

Monday, March 22, 2010, 15:15–15:30, H6

Vacancies in aluminium and dilute Al alloys - an investigation by positron annihilation spectroscopy — •Meng Liu, Benedikt Klobes, and Karl Maier — Helmholtz-Institut für Strahlen- und Kernphysik, Rheinische Friedrich-Wilhelms-Universität Bonn, Nußallee 14-16, D-53115 Bonn

Aluminium and its alloys are widely applied in our daily lives as construction material, food packages and so on due to their unique properties, namely light weight and high strength. In case of age-hardenable Al alloys used e.g. in automotive and aviation industry they are greatly influenced by precipitates which are usually formed through vacancy driven diffusion. In Al alloys quenched-in vacancies will be trapped by solute atoms, but in pure aluminium they diffuse to the surface, grain boundaries, dislocations and disappear at room temperature. In this study HCl solution cooled to 203 K is used instead of water as quenching medium in order to optimize quenching rate, and to freeze vacancies at such temperature. Based on this quenching method a vacancy reference in pure aluminium is obtained by using positron annihilation techniques, which are especially suitable for the investigation of open volume defects, since positrons are highly sensitive to vacancies. The results are then compared to dilute Al alloys. In this way information about solute concentration around vacancies and/or their relaxation can be obtained.