Analytical,numerical, and experimental analysis of inverse macrosegregation during upward unidirectional solidification of Al-Cu alloys |
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Authors: | Ivaldo L Ferreira Carlos A Santos Amauri Garcia Vaughan R Voller |
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Affiliation: | (1) the Department of Materials Engineering, State University of Campinas, UNICAMP, 13083-970 Campinas, SP, Brazil;(2) the Department of Civil Engineering, University of Minnesota, 55455-116 Minneapolis, MN |
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Abstract: | The present work focuses on the influence of alloy solute content, melt superheat, and metal/mold heat transfer on inverse
segregation during upward solidification of Al-Cu alloys. The experimental segregation profiles of Al 4.5 wt pct Cu, 6.2 wt
pct Cu, and 8.1 wt pct Cu alloys are compared with theoretical predictions furnished by analytical and numerical models, with
transient h
i profiles being determined in each experiment. The analytical model is based on an analytical heat-transfer model coupled
with the classical local solute redistribution equation proposed by Flemings and Nereo. The numerical model is that proposed
by Voller, with some changes introduced to take into account different thermophysical properties for the liquid and solid
phases, time variable metal/mold interface heat-transfer coefficient, and a variable space grid to assure the accuracy of
results without raising the number of nodes. It was observed that the numerical predictions generally conform with the experimental
segregation measurements and that the predicted analytical segregation, despite its simplicity, also compares favorably with
the experimental scatter except for high melt superheat. |
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Keywords: | |
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