Corrosion Behavior of As-Casted and Semisolid Mg-Al-Zn Alloys in Salt Solution

The corrosion behaviors in salt solution immersion test of as-casted and semisolid Mg-Al-Zn alloys with different compositions were analyzed by optical microscopy,SEM and EDS.The results demonstrate that when the content of zinc element was less than 1wt%,the corrosion rate of as-casted specimens was higher than that of the corresponding semisolid specimens.When the content of zinc element was more than 3wt%,the corrosion rate of as-casted specimens was lower than that of the corresponding semisolid specimens,and the corrosion of as-casted specimens occurred on the surface.The corrosion rate was affected by zinc content and solid particle size and quantity.The higher the zinc content,the lower the corrosion rate of as-casted specimens.The more the solid particle number and the smaller the solid particle size,the higher the corrosion rate of semisolid specimens.