Lateral heat flux and remelting during growth into the mushy-zone

In the context of dendritic rapid solidification, the goal of this work was to develop a model that describes growth of the stable phase in the presence of a preexisting metastable phase without requiring in-depth knowledge of the local geometry of the growing dendrite or the growth environment. Results facilitate predictive computational materials modeling of the transformation sequence, solidification path and microstructural evolution during industrial casting operations. The model was evaluated using mushy-zone growth velocity data from Fe-Co and Fe-Cr-Ni alloys. The Fe-Co alloys that were tested are hyper-peritectic compositions, while the Fe-Cr-Ni alloys were evaluated as pseudobinary hypoeutectic compositions. The results show that for a given heat flux there will be a minimum undercooling for which dendritic growth can be supported. The predicted growth velocity which corresponds to that minimum undercooling agrees reasonably well with the measured experimental growth velocity data suggesting that the growth of the stable phase into the mushy zone occurs under the minimum conditions required to support dendritic growth.

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