Particle Reinforced Metals

A. Hauert, R. Müller, A. Miserez, C. San Marchi, M. Kouzeli, A. Rossoll, L. Weber, A. Mortensen

This was an extensive investigation of the processing, structure and mechanical behaviour of open-celled aluminium-based foams sponsored by the Swiss National Science Foundation. Project aims were to clarify relationships between microstructural parameters and mechanical and physical properties of particle reinforced metals. To this end, packed beds of ceramic particles were infiltrated with molten aluminum-based matrices to produce, after solidification, a composite material containing roughly equal amounts of metal and ceramic. The microstructural simplicity of these metal matrix composites was exploited to investigate, with minimal ambiguity, the link that exists between such microstructural parameters as metal matrix performance, ceramic particle nature, shape or size and composite properties. Focus was placed on two critical mechanical tests for these materials: tensile deformation and fracture toughness. Among the physical properties electrical conductivity was studied in detail. We have shown in particular that, despite their high ceramic content, these materials can be made remarkably strong and tough. We have adapted current micromechanical models to predict in relatively simple terms the non-linear flow curve of these materials, incorporating non-linear matrix deformation and internal damage. We have also explained, with a local load sharing model of damage in these materials, their brittle to ductile transition in tensile fracture.

 

Four-point bend bar of a composite combining roughly 50% alumina with 50% aluminum.Note the high level of plastic deformation that can be achieved in this material: combining metal and ceramic need not produce a brittle material, provided that the ingredients and the processing are of high quality.

 

A selection of scientific articles from this work:

 

M. Kouzeli and A. Mortensen, Size dependent strengthening in particle reinforced aluminium. Acta Materialia, 2002. 50(1): p. 39-51 and (corrigendum) Acta Materialia, 2003. 51(20): p. 6493-6496.