Iron Phases in Model Al-Mg-Si-Cu Alloys

Abstract

Iron phases present in alloys from the 6xxx series affect the workability behaviour of these alloys. Iron in these alloys occurs in the form of intermetallic phases and AlFe, α-AlFeSi, β- AlFeSi eutectics. The homogenisation treatment is carried out to induce the transformation of  phase into phase The aim of the studies was EDX and EBSD analysis by scanning microscopy of iron phases present in model alloys based on 6061 system, characterised by the silicon-iron ratio Si/Fe=0,5 and 1, examined in as-cast condition and after homogenisation, followed by a comparison of the detected phases with phases present in industrial ingots. In 6061 alloy, copper in the amount of 0,4wt.% occurred in the solid solution of aluminium. The EDX analysis proved that copper atoms were embedded also in iron precipitates, and scarce phases of an AlxCuy type were being formed. Different content of magnesium in the examined alloys (0,8 and 1,2wt.%) affected not only the quantitative content of Mg2Si phases, but also the presence of AlFe phases in alloy with small content of Si (0,4wt.%) and high content of Mg (1,2wt.%).