Relationship Between Aluminum-Rich/Intermetallic Phases and Microhardness of a Horizontally Solidified AlSiMgFe Alloy

摘要

An experimental study with an A356-AlSiMgFe alloy was developed to evaluate the microhardness performance in the microstructure resulting of an unsteady-state horizontal solidification process. The Al-7wt%Si-0.3wt%Mg-0.15wt%Fe alloy was elaborated and directionally solidified in a water-cooled horizontal solidification device. In order to experimentally determine the cooling and growth rates (V L and T R , respectively), a thermal analysis was also conducted during solidification. Microstructural characterization by optical microscopy, SEM/EDS elemental mapping and microanalysis of the punctual EDS compositions allowed to observe the presence of an Al-rich dendritic phase (Al (α) ) with interdendritic phases second composed of an eutectic mixture: Al (α-eutectic) + Si + Al 8 Mg 3 FeSi 6(π) + Mg 2 Si (θ) . Furthermore, the dendritic microstructure was characterized by measuring the secondary dendritic spacings (λ 2 ) along the horizontally solidified ingot. Higher HV values were observed within the eutectic mixture.