Abstract
The detailed microstructure of cast aluminum alloys based on Al-7 pct Si-0.3 pct Mg (A356) has been investigated as a function of Fe and Cr content and solidification rate. It was found that the coarse β phase (FeSiAl5) platelets, which form during solidification of alloys containing Fe, are replaced by “Chinese script” α(bcc) [(Cr, Fe)4Si4Al13] dendritic particles when Cr is added. Coarse π (FeMg3Si6Al8) phase and fine α(bcc) precipitates were found in all of the investigated alloys. Quantitative metallography showed that the length of β phase platelets and the arm length of α(bcc) dendrites increased with decreasing solidification rate and increased Fe content. The T6 heat treatment resulted in the dissolution of π phase and the uniform fine scale precipitation of β′(Mg2Si) in the aluminum rich phase.
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Formerly with Chalmers University of Technology, Göteborg, Sweden
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Gustafsson, G., Thorvaldsson, T. & Dunlop, G.L. The influence of Fe and Cr on the microstructure of cast Al-Si-Mg alloys. Metall Trans A 17, 45–52 (1986). https://doi.org/10.1007/BF02644441
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DOI: https://doi.org/10.1007/BF02644441