Microstructure, Mechanical Properties and Corrosion Behavior of Zr-Containing AlSi5Cu2Mg Alloy

The aim of this paper was to analyze the impact of varying zirconium addition on selected properties of AlSi5Cu2Mg alloy. The results of this research showed that zirconium addition in the range of 0.05 to 0.20 wt. % caused a decrease in ultimate tensile strength and yield strength of the experimental alloys after T7 heat treatment, probably due to the formation of primary Al3Zr intermetallic phases. These phases were observed as an individual plates or as a formation of two crossed plate-like phases. Potentiodynamic polarization tests in 3.5% NaCl solution revealed that addition of Zr had a positive effect on thermodynamic corrosion stability of the AlSi5Cu2Mg alloy due to shift of the corrosion potential to a more positive values for all as-cast samples. Addition of Zr in the as-cast alloys improved corrosion kinetics by lowering of corrosion current density.