Analysis of microstructure in AlSi7Mg0.3 cast alloy with different content of Fe.

Abstract

Abstract The use of recycled alloys brings potential energy savings, and generates less CO2 emission compared to primary aluminum production, but it is necessary to take into account their specifics properties. The properties of the secondary aluminum alloys are comparable to primary alloys, but important attention must be paid due to the higher iron content. Iron with the presence of other elements in the alloy creates intermetallic compounds which have negative influence especially on the mechanical properties. It is impossible to remove iron from melt by standard operations. Some elements eliminates iron by changing iron intermetallic phase morphology, decreasing its extent and by improving alloy properties. Therefore, the effects of different content of Iron (Fe) on the microstructure and the morphology of the intermetallic iron phases of AlSi7Mg0.3 alloy casted in to the sand molds were investigated. For influencing their morphology formation the heat treatment T6 (according standards) and addition of Manganese (Mn) were used in some bars. 2D and 3D metallographic and image analysis have been performed to measure the microstructural changes occurring at different Fe, Mn levels and heat treatment conditions. The study confirms that T6 have influence on to size of Fe-rich phases (especially in needles form), but the increasing length of Fe-needles intermetallic phases with increasing content of Fe did not by confirmed.