On the Effect of Tramp Elements on the Phase Assemblage of Aluminum Alloys Synthesized with Increased Recycled Content
摘要
AluminumAluminum alloys alloysAluminum alloys are relatively easy to recycle because of their low melting point compared to other metallic materials. More importantly, aluminum remelting is much less energy-intensive and CO \(_2\) -emitting than its primary extraction. Sorting is the best practice to avoid contamination. Unfortunately, this strategy is not perfect and leads to the presence of paints, organics, and other metals. The latter introduces tramp elements which affect the phase assemblage of aluminum alloysAluminum alloys as well as their physical/mechanical properties. Traditionally, cast alloys were targeted as recyclingRecycling vectors because of their tolerance to impurities. The higher demand for wrought alloys makes these materials ideal candidates to increase recyclingRecycling activities. This work reports a series of experiments on the controlled contamination of a commercial 6061 wrought alloy with various concentrations of Fe and V. It showed that in the presence of 1 wt.% of iron contamination (which is well above typical contamination concentrations), vanadium partially modifies the morphology of the AlFeSi- \(\alpha \) phase that forms upon casting without the precipitation of Al \(_3\) V intermetallics. This phenomenon appears to be induced by the substitution of iron with vanadium in this solid solution. Further vanadium addition to the Fe-contaminated 6061 promotes the formation of Al \(_{18}\) V \(_{2}\) Mg \(_{3}\) intermetallics which have polygonal shapes under as-cast conditions. Computational thermodynamic simulations performed with FactSage showed that a Scheil cooling solidification process leads to a precise description of the as-cast phase assemblage of the commercial 6061 alloy without additional impurities.