Regensburg 2007 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 11: Interfaces III

MM 11.3: Vortrag

Montag, 26. März 2007, 15:15–15:30, H6

Al-Al Compound Casting — •Konrad Papis, Peter Uggowitzer, and Jörg Löffler — ETH Zurich, Laboratory of Metal Physics and Technology, Zurich, Switzerland

'Compound casting' is a process where a melt is cast onto or around a solid metallic 'insert'. It is the realization of a simple joining procedure for light metals aimed at weight-saving. Difficulties inherent in joining aluminium are its natural oxide layer and the formation of intermetallic phases. In this project, both the solid substrate and the melt used are aluminium alloys containing various alloying elements (Cu, Si, Zn in the melt, Mg in the substrate). Compounds with flawless interfaces (no contraction defects, no oxides) were successfully produced by replacing the oxide layer with a zinc layer. This was accomplished by pickling the substrate in a solution containing zincate ions, implying a redox reaction by which zinc is deposited in its metallic form. The composition and mechanical properties of the compounds' interfacial regions were investigated by SEM/EDX and microhardness measurements following the 'compound casting' process and successive heat treatments. DICTRA calculations were carried out to simulate the diffusion processes at the interface. The results from the mechanical characterization were compared to the simulations, the conclusion being that diffusion of alloying elements led to precipitation hardening of the compound.