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Mechanical performance of structurally optimized AlSi7 aluminum foams – an experimental study
Author(s) -
Dirk Lehmhus,
Matthias Busse
Publication year - 2014
Publication title -
materialwissenschaft und werkstofftechnik
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.285
H-Index - 38
eISSN - 1521-4052
pISSN - 0933-5137
DOI - 10.1002/mawe.201400354
Subject(s) - liquidus , solidus , blowing agent , materials science , composite material , alloy , microstructure , aluminium , decomposition , compression (physics) , foaming agent , atmospheric temperature range , chemistry , thermodynamics , porosity , polyurethane , physics , organic chemistry
AlSi7 aluminum foams produced via the powder compact melting process suffer from deficiencies in the pore structure that are linked to the mismatch between the decomposition temperature range of the common blowing agent TiH 2 and the solidus and liquidus temperature of the matrix alloy. To alleviate these deficiencies, two main paths have been discussed in the past: One is the adaptation of the matrix alloy towards lower melting temperatures, the other the modification by heat treatment of the foaming agent itself, which leads to higher decomposition temperatures. The present paper compares the mechanical response of foams produced according to the second approach to that of the reference material, AlSi7 foamed using untreated TiH 2 as blowing agent. Mechanical performance is evaluated based on uniaxial, quasi‐static compression tests over a wide range of densities. In parallel, the pore and microstructure of the respective materials is characterized using metallographic sections and computed tomography for image acquisition, as well as image analysis to derive quantitative parameters. Foams based on thermally treated blowing agents show increased compressive strength at technically relevant density levels. The advantage is lost at very high porosities in excess of 85–90% only.