The influence of Ag and Si additions on the electrochemical behavior in extruded Mg-Zn alloys

Development of new wrought magnesium alloys for the automotive industry has increased in recent years, due to their high potential as structural materials for low density and high strength/weight ratio demands. However, the poor mechanical properties and low corrosion resistance of the magnesium alloys have led to a search for new kinds of magnesium alloys, for better strength, ductility, and high corrosion resistance. The main objective of this research is to investigate the corrosion behavior of new magnesium alloys: Mg-Zn-Ag (ZQ) and Mg-Zn-Si (ZS). The ZQ6X and ZS6X alloys were prepared using the hot extrusion method. AC and DC polarization tests were carried out on the extruded rods, which contain different amounts of silver or silicon. The microstructure was examined using optical and electron microscopy (SEM) and energy dispersive spectrometry (EDS). The results showed that the silver addition decreased corrosion resistance. The addition of silicon also affected corrosion behavior. These results can be explained by the effects of alloying elements on the microstructure of Mg-Zn alloys, such as grain size and precipitates caused by the change in precipitation, and by recrystallization behavior.