Elimination of Negative Effect of Fe in Secondary Alloys AlSi6Cu4 (En Ac 45 000, A 319) by Nickel

Abstract

Abstract Submitted article deals with influence of iron based phases segregation by nickel, which is in literature known as iron based phases corrector. Iron is one of the most common impurities that can be found in Al-Si alloys. It is impossible to remove iron from melt by standard operations, but it is possible to eliminate iron negative effects by addition of other elements, that enables segregation of iron in form of intermetallics with less harmful effect. For melt treatment was selected an exact alloy with requested iron content - master alloy AlNi20. Influence of nickel was evaluated quantitatively by chemical analysis (solubility), thermal analysis and microstructure evaluation. Experimental results analysis shows a new view on solubility of iron based phases during melt preparation and treatment with higher iron content and also nickel effect as iron corrector of iron based phases. It can be concluded that nickel did not influenced iron based phases (β-phases), it does not change their type into more favorable form. As an initial impulse for starting this work was insufficient theoretical knowledge of usage secondary alloys Al-Si-Cu with higher iron content and its appropriate elimination in process of castings production for automotive industry. Increased iron content in alloys causes segregation of iron phases in various shapes and types during solidification, which subsequently affects quality, soundness and lifetime of castings. Because of increased demands for casting quality, final mechanical properties and effort to reduce costs, it is necessary to look for compromises in casting production from secondary alloys with occurrence of various impurities.