Mohsen Ostad Shabani* and Ali Mazahery
Department of Materials Science, Lenjan Branch, Islamic Azad University, Isfahan, Iran
*e-mail: ostadshabany@iauln.ac.ir
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 micro-
structure 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.
Keywords: aluminum, SDAS, tensile, microstructure
DOI: 10.3103/S1067821214050150
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