Simulation and examination of directional solidification characteristics of hyper-eutectic Al-38wt%Cu alloys

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Sawatzky, Trevor
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The present work deals with the solidification behavior of hyper-eutectic Al-38wt%Cu alloy. Various aspects of solidification in the Al-Cu system are studied. The formation of channel segregates or freckles during vertical solidification of Al-38wt%Cu alloy is simulated. The simulation is based on a mathematical model of dendritic solidification, in which the solid plus liquid zone is modeled as an anisotropic porous medium of variable porosity. The alloy solidifies from an initial melt and proceeds until the alloy is completely solidified. The final macrosegregation can be predicted. A three zone gradient-freeze QUESTS (Queen's University Experiment on the Shuttle T ansportation System) furnace was designed to carry out unidirectional solidification experiments. The experiments were carried out under different cooling conditions. The temperature gradients ranged from 1000 to 3500 (K/m) with a constant cooling rate of 3.5 (K/min), producing growth rates between 6-21 (cm/hr). The faceting behavior of primaryAl2Cu ([theta]) phase has been examined as a function of growth rate. The segregation phenomena in the hyper-eutectic Al-Cu alloy was examined for both simulation and experiment. (Abstract shortened by UMI.)