Regensburg 2010 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 5: Diffusion and Point Defects I
MM 5.2: Vortrag
Montag, 22. März 2010, 10:30–10:45, H6
The influence of Au on the decomposition of Al-Cu — •Benedikt Klobes1, Osman Balarisi1, Meng Liu1, Karl Maier1, and Torsten Staab2 — 1Helmholtz-Institut für Strahlen- und Kernphysik, Nußallee 14-16, 53115 Bonn — 2Fraunhofer ISC, Neunerplatz 2, 97082 Würzburg
Al alloys based on the binary Al-Cu system are important structural materials since they combine light weight with high strength. Their favourable mechanical properties are induced by precipitates of nanometer size which are formed due to the vacancy driven transport of solute atoms. Usually, this precipitation process is significantly influenced by other microalloying elements, e.g. the addition of Mg accelerates and amplifies the hardness increase during ageing. In contrast, microalloying additions of Au inhibit the decomposition and age hardening of the alloy. By means of positron annihilation and x-ray absorption spectroscopy, with which the essential ingredients of age hardenable alloys, namely vacancies and solute atoms, can be probed, we show that Au atoms trap quenched-in vacancies. Since the vacancy mechanism of diffusion is surpressed this way, no age hardening can occur.