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Deformation and fracture behavior of eutectic aluminum-silicon casting alloys Dowdle, Eric James


The effect of silicon particle size and morphology on the deformation and fracture behavior of a binary aluminum silicon casting alloy was studied. Castings of eutectic composition were solidified either slowly without modifiers, or quickly with strontium modification to produce two different as-cast microstructures. Solution treatment of the castings was performed for various lengths of time at 540°C to further differentiate the structures. Quantitative image analysis was used to describe the size and shape of the silicon particles. Samples were tested in both tension and compression. Particle sizes were in a region where, neither continuum plasticity nor dislocation based models can fully predict the effect of the silicon phase on the deformation behavior of the alloy. The deformation and fracture behavior were dependent on the size and shape of the silicon particles. Damage, in the form of particle cracking, degraded the strength of the alloy and reduced ductility. This was compared to a simple analytical model which describes the effect of damage on flow in a composite material.

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