Automotive copper and magnesium containing cast aluminium alloys: Report on the correlation between Yttrium modified microstructure and mechanical properties

Abstract

An experimental investigation is carried out in order to measure and thus report the effect of SDAS values on the mechanical properties of the Yttrium modified casting Al alloys. Microstructural features and the alloy composition determine the mechanical properties of the as-cast Al alloys. The solidification rate plays the main role on the microstructural characteristics including primary and secondary dendrites arm spacing (DAS and SDAS), also the fraction, size and distribution of defects, eutectic silicon and intermetallic phases. In this study, Yttrium is used as a chemical modifier to the cast Al alloys in an attempt to transform the acicular shape of the Si to the fibrous morphology. The investigation of the samples show the presence of the pores and voids in the microstructure of the as-cast Y modified alloy. The typical cast microstructure shows dendritic Al accompanied with eutectic Si and Al2Cu, Al15(Fe, Mn)3Si2 and other complex multi-element intermetallic. Based on the findings of the tensile tests, strength of the Y modified alloy declines with increasing the SDAS values.