Thermodynamic analysis and mechanical properties of cast aluminum alloy A357 with Cu, Ag and Sm additions

Abstract

Computational thermodynamics has been conducted on the aluminum alloy A357 with additions of Cu, Ag and Sm. The analysis included the determination of isopleth sections and phase fractions as a function of temperature. Scheil solidification diagrams were calculated showing the development of microsegregation. Calculation of precipitation driving force for the strengthening phases Mg2Si and θ (Al2Cu) were conducted as a function of temperature and composition. These calculations established the recommended ageing temperature of the alloys. The modified ageing treatment (relative to the conventional A357 alloy) resulted in improved combinations of strength and ductility. These improvements were attributed to the finer particle dispersions produced with the lower temperature ageing treatment.