Influence of microstructure development on mechanical properties of alsi7mgcu alloy

Abstract

The design of materials through the selection of the chemical composition, thermodynamic modelling, melt treatment, correctly developed casting technology followed by adequate heat treatment could improve casting properties. A wide range of complex reactions and intermetallic phases occurs due to numerous alloying (Si, Mg, Cu) and trace elements (Fe, Mn) interaction. Determination of solidification sequence was performed by modeling of equilibrium phase diagram, simultaneous thermal analysis and metallographic investigations. Microstructure revealed needle-like Al5SiFe and Chinese script phase Al15(Fe,Mn,Cu)3Si2 enriched in copper. Copper addition resulted in formation of compact complex intermetallic phases Al5Cu2Mg8Si6 and Al8FeMg3Si6. Solidification ended with secondary eutectic phases Mg2Si and Al2Cu. Wide spectra of favourable intermetallic phases comprehend to the tensile mechanical properties development already in as-cast state. Comparison of yield and tensile strength with commonly used AlSi7Mg alloy indicates significant increase of investigated properties for innovative chemistry of AlSi7Mg(Cu) alloy in as-cast state.