FIGURE 1: Optical micrograph of polished cross-section of syntactic foam, showing hollow silica-mullite microspheres within an aluminum matrix. Some defects (fragmented or infiltrated microspheres) are also visible.
Syntactic aluminum foams are produced by pressure infiltration of liquid aluminum into packed preforms of cenospheres (hollow silica-mullite ceramic spheres with about 50 microns diameter). The resulting material has the chararcteristics of a metal matrix composite, except that the reinforcement is hollow, resulting in a density of about 1.5 g/cm3. The mechanical properties at ambient temperature of these composite-foams were previously studied by Dorian Balch (a prior PhD student currently at LLNL, see list of references below). Olivier is now measuring the compressive creep properties of these syntactic foams and modeling these results using the finite-element method. It is expected that they will display high creep strength, as for composites, while maintaining their low density, as for foams.
Related References
- D.K. Balch, J.G. O’Dwyer, G.R. Davis, C.M. Cady, G.T. Gray, D.C. Dunand
“Plasticity and Damage in Aluminum Syntactic Foams Deformed under Dynamic and Quasi-Static Conditions”
Materials Science and Engineering, in print. - D.K. Balch, D.C. Dunand
“Load Partitioning in Aluminum Syntactic Foams Containing Ceramic Microspheres ”
Acta Materialia, submitted for publication - D. Balch, D.C. Dunand
“Mechanical Properties and in-situ Diffraction Strain Measurements in Aluminum-Mullite Microsphere Syntactic Foams Produced by Liquid Metal Infiltration”
Processing and Properties of Lightweight Cellular Metals and Structures
(edited by A. Ghosh, T. Sanders, D. Claar)
TMS, Warrendale, p. 251-260, (2002).
