Abstract
A numerical micromodel has been developed to simulate the evolution of equiaxed primary phase grains during the solidification of alloys in the systems Al–Cu, Al–Si, Al–Mg, and Al–Zn. The microstructures generated have then been used to model liquid permeability as a function of composition for each system, for a given solid fraction and cooling rate. In all systems a marked minimum occurred in the permeability curve at a value < ∼1 wt-% solute. The composition corresponding to the minimum permeability tended to increase with increasing equilibrium partition coefficient. It is argued, for each system, that the composition displaying minimum permeability would correspond to that composition exhibiting maximum susceptibility to hot tearing. Comparison of the permeability data with experimental hot tear test data for the same systems reveals the limitations of most hot tear tests.
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