THERMODYNAMIC ANALYSIS AND MECHANICAL-PROPERTIES OF COST ALUMINUM-ALLOY A357 WITH CU, AG AND SM ADDITIONS

Computational thermodynamics has been conducted on the aluminum alloy A357 with additions of Cu, Ag and Sm. The analysis included the determ ination of isopleth sections and phase fractions as a function of temp erature, Scheil solidification diagrams were calculated showing the de velopment of microsegregation. Calculation of precipitation driving fo rce for the strengthening phases Mg2Si and theta (Al2Cu) were conducte d as a function of temperature and composition, These calculations est ablished the recommended ageing temperature of the alloys. The modifie d 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 lo wer temperature ageing treatment.