The influence of Cr content on the microstructure and mechanical properties of AlSi9Cu3(Fe) die-casting alloys

▶ Primary and proeutectic α-Alx(Fe,Mn,Cr)ySiz intermetallics show mainly polyhedral, star-like and blocky morphology in AlSi9Cu3(Fe) alloy. ▶ The area fraction of Fe-rich intermetallic compounds increases as the Cr content increases. ▶ The amount of sludge particles can be estimated from the sludge factor by a linear relationship. ▶ Sludge forms mainly in the shot sleeve before the melt entered the die cavity and segregates in the central region of the cross-section of specimens. ▶ The UTS and, mostly, the elongation to fracture decrease as the Cr level exceeds 0.12 wt.%, while the Cr addition do not affect the YS of the alloy.