Corrosion of new wrought magnesium alloys

The development of new components with 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 limited mechanical properties of the magnesium alloys have led to search new kind of magnesium alloys for better strength and ductility. The main objective of this research is to investigate the mechanical properties and the corrosion behavior of new wrought magnesium alloys; Mg-Zn-Ag (ZQ) and Mg-Zn-Si (ZS) alloys. The ZQ6X and ZS6X samples were fabricated using hot extrusion method. Tensile tests and immersion tests were carried out on the specimens from the extruded rods, which contained different amounts of silver or silicon, in order to evaluate the mechanical properties and corrosion behavior. The microstructure was examined using optical and electron microscopy (TEM and SEM) and EDS. The results showed that the addition of silver improved the mechanical properties but decreased the corrosion resistance. The addition of silicon improved both mechanical properties and corrosion resistance. These results can be explained by the effects of alloying elements on the microstructures of the Mg-Zn alloys such as grain size and precipitates caused by the change in precipitation and recrystallization behavior.