Berlin 2005 – scientific programme

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M: Metallphysik

M 47: Mechanische Eigenschaften III

M 47.2: Talk

Tuesday, March 8, 2005, 15:00–15:15, TU H111

Control of the Porous Structure of Aluminium Foams — •B. Matijasevic-Lux¹, Th. Lonkai^2,3, S. Fiechter², N. Wanderka², P. Schuber-Bischoff², and J. Banhart^2,3 — ¹Institute of Materials Sciences and Technology, Technical University Berlin, Hardenbergstr. 36, 10623 Berlin, Germany — ²Hahn-Meitner-Institut Berlin, Glienicker Str. 100, 14109 Berlin, Germany — ³Institute for Applied Physics, University of Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany

A high rigidity combined with a low weight makes aluminium foams a very promising material for modern engineering. The quality of metal foams depends on the homogeneity of the porous structure. We succeeded in controlling the homogeneity of the porous structure of aluminium foams by heat treatment of the blowing agent TiH₂ under air. The TiH₂ powder was characterised by thermal analysis, mass spectrometry, X-ray and neutron diffractometry (XD,ND) and transmission electron microscopy (TEM). Mass spectrometry showed that hydrogen release from as-received TiH2 powder in argon shows two decomposition peaks while after pre-treatment in air the first decomposition stage is eliminated and the second shifted to higher temperatures depending on the nature of heat treatment. The elimination of the first decomposition improved the homogeneity of the porous structure of the metal foam significantly. The effect was attributed to oxide layers around the cores of TiH2 particles, observed by a combination of XD, ND and TEM experiments, which build up during pre-treatment and act as diffusion barriers to hydrogen. The oxide layers consists of two different titanium oxides, namely tetragonal TiO₂ and hexagonal Ti₃O of about 100 nm thickness.