### 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:

L. Weber, M. Kouzeli, C. San Marchi, and A. Mortensen, “On the Use of Considere’s Criterion in Tensile Testing of Materials which Accumulate Internal Damage”, *Scripta Materialia*, 41 (5) 549-551, 1999.

M. Kouzeli, L. Weber, C. San Marchi, and A. Mortensen, “Quantification of Microdamage Phenomena during Tensile Straining of High Volume Fraction Particle Reinforced Aluminium”, *Acta Materialia*, vol. 49 (3) pp. 497-505, 2001.

M. Kouzeli, L. Weber, C. San Marchi and A. Mortensen, “Influence of Damage on the Tensile Behavior of Pure Aluminium Reinforced with ≥ 40 vol. Pct Alumina Particles”, *Acta Materialia*, 49 (18), 3699-3709 (2001).

M. Kouzeli, C. San Marchi, A. Mortensen: Effect of reaction on the tensile behavior of infiltrated boron carbide-aluminum composites, * Mater. Sci. * ,

**337**(1-2), 2002, 264-273.

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.

C. San Marchi, Fahe Cao, M. Kouzeli, A. Mortensen: Quasistatic and Dynamic Compression of Aluminum-Oxide Particle Reinforced Pure Aluminum, * Mater. Sci. * ,

**337**(1-2), 2002, 202-211.

L. Weber, C. Fischer, A. Mortensen, “On the Influence of the Shape of Randomly-oriented, Non-conducting Inclusions in a Conducting Matrix on the Effective Electrical Conductivity”, *Acta Materialia*, vol. 51 (2), pp. 495-505 (2003).

A. Miserez, A. Rossoll and A. Mortensen, “Fracture of Aluminium Reinforced with Densely-Packed Ceramic Particles: Link between the Local and the Total Work of Fracture”, *Acta Materialia*, vol. 52(5), pp. 1337-1351 (2004).

A. Miserez, A. Rossoll, and A. Mortensen, “Investigation of Crack-tip Plasticity in High Volume Fraction Ceramic Particle Reinforced Metal Matrix Composites”, *Engineering Fracture Mechanics*, vol. 71, pp. 2385-2406 (2004).

A. Miserez and A. Mortensen, “Fracture of Aluminum Reinforced with Densely-Packed Ceramic Particles: Influence of Matrix Hardening”, *Acta Materialia*, vol 52 (18) pp. 5331-5345 (2004).

A. Miserez, R. Müller, and A. Mortensen, “Increasing the strength/toughness combination of high volume fraction particulate metal matrix composites using an Al-Ag matrix alloy”, *Advanced Engineering Materials, *vol. 8 (1-2), pp. 56-62 (2006).

R. Müller and A. Mortensen, “Simplified prediction of the monotonic uniaxial stress-strain curve of non-linear particulate composites”, *Acta Materialia*, vol. 54 (8) pp.2145-2155, 2006 .

R. Mueller, A. Rossoll, L. Weber, M.A.M. Bourke, D.C. Dunand and A. Mortensen, Tensile flow stress of ceramic particle reinforced metal in the presence of particle cracking, *Acta Materialia*, vol. 56 (16) pp. 4402-4416 (2008).

A. Hauert, A. Rossoll, and A. Mortensen, “Ductile-to-brittle transition in tensile failure of particle reinforced metals”, Journal of the Mechanics and Physics of Solids, vol. 57 pp. 473-499 (2009).

A. Hauert, Andreas Rossoll, Andreas Mortensen, “Young’s modulus of ceramic particle reinforced aluminium: measurement by the Impulse Excitation Technique and confrontation with analytical models”, Composites Part A, 40 (2009) 524–529 .

A. Hauert, A. Rossoll, and A. Mortensen, “Particle fracture in high volume fraction ceramic reinforced metals: governing parameters and implications for composite failure”, Journal of the Mechanics and Physics of Solids, vol. 57 (11), pp. 1781-1800 (2009).

A. Hauert, A. Rossoll, A. Mortensen, “Fracture of high volume fraction ceramic particle reinforced aluminium under multiaxial stress”, Acta Materialia, vol. 58 (6), pp. 3895-3907 (2010) .