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Unpublished Paper

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Wrought aluminum-based alloys exhibit superior physical and mechanical properties compared to conventional shape casting alloys. However, wrought alloys cannot be cast into near net shapes because they develop hot tears and hot cracks during solidification. For this reason, these alloys are typically cast into ingots and are subsequently brought to final shape by mechanical processes such as rolling, extrusion, drawing and forging. These processes significantly increase the cost of the manufactured component. Controlled Diffusion Solidification (CDS) is a novel process that allows casting of wrought alloys directly into final shapes that are free of hot tears; thus CDS eliminates the added cost of machining. The process follows a different route from conventional casting methods. In CDS two liquid alloys of predetermined composition and temperature are mixed together so that upon solidification the resultant alloy has a globular rather than a dendritic microstructure as shown in Figure 1. The hot tearing tendency of wrought alloys originates from the inadequate permeability of their dendritic network, which obstructs the flow of interdendritic liquid and hinders compensation for shrinkage. The nondendritic microstructure made possible by CDS minimizes hot-tearing thus enabling wrought alloys to be cast directly. The CDS has the potential to:

  • Reduce the cost of multiple component assemblies
  • Minimize several typical casting defects that are associated with solidification
  • Reduce the time required to fabricate assemblies
  • Reduce process variability by controlling the solidification
  • Increase casting applications



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