The influence of Fe and Mn content and cooling rate on the microstructure and mechanical properties of A380-die casting alloys

Abstract

In the present investigation, the microstructure and tensile properties of aluminium die-cast alloys, based on A380, are studied in details as a function of the iron and manganese content and solidification rate. One set of experiments was designed to examine the ?solely? effect of Fe content, which varied from 0.1 up to 1.6 wt % and another set with manganese additions, Mn:Fe ~ 1:2. Three solidification rates corresponding to ~ 10, 25 and 60 ?m in secondary dendrite arm spacing, SDAS, respectively were employed by using the unique gradient solidification technique. Microstructure analysis reveals that at relatively high cooling rates and iron levels, the iron-rich precipitates are suppressed to some extent and the strength is maintained at high levels, but the ductility is gradually decreased. The amount of iron-rich intermetallics does not appear to influence the size and area fraction of porosity and consequently the result suggests that tensile properties have not been adversely affected by porosity level. These results offer additional insight into commonly discussed microstructure features and their role in the determination of the quality and soundness of Al-Si cast alloys.