J. Phys. IV France 120 (2004) 61-68
The rate of solidification and the effects of local composition on the subsequent nucleation of Al20Cu2Mn3 dispersoid phase in Al-4Cu-0.3Fe-0.4Mn-0.2Si alloysT.L. Zoeller1 and T.H. Sanders Jr.2
1 Mechanical Engineering, 801 Ferst Drive ,Grad Box 230, Georgia Institute of Technology, Atlanta, GA 30332-0405,USA
2 Materials Science and Engineering, 771 Ferst Drive Georgia Institute of Technology, Atlanta, Georgia, 30332-0245, USA
Following solidification, an aluminum alloy microstructure is highly segregated. The microstructure consists of cored dendrites with various soluble and insoluble phases present in the inter-dendritic regions. The solidification rate has a marked effect on the amount of coring as well as grain dimensions and second phase particle size and spacing. Post-solidification cooling rates as well as subsequent heat treatments also affect the evolution of the microstructure. Understanding the effects of these thermal treatments is important in explaining differences in microstructures that are observed in alloys of identical compositions. The focus of this study is to determine the interaction between the coring of copper across dendrites during solidification and the precipitation of dispersoids during the homogenization treatments of an alloy. An aluminum alloy whose composition is in the range of Al-4Cu-0.3Fe-0.4Mn-0.2Si is ideally suited for this study for several reasons. First it is similar to a host of commercial aluminum copper alloys, and the presence of Mn, Fe, and Si affect the distribution of particles that control grain morphology in these alloys. Preliminary experimental results are discussed. Current numerical analysis techniques will be examined and possible methods to treat the problem will be presented.
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