Abstract
Corrosion behavior of sand-casted Mg-(0-5.3%)Al and Mg-5.3%Al-(0-2.7%) Zn alloys have been investigated by salt spraying test (SST). The corrosion resistance increased with an increase of Al content in Mg-Al alloys, and more than 1% content of Zn in Mg-5.3%Al-Zn alloys. These behavior were seemed to depend on the volume fraction of nodule structure. Cross-sectional microstructure after corrosion test showed that the matrix was preferentially attacked and the nodule structure was more resistant to corrosion. These dependence of corrosion resistance on the nodule content was discussed from the view point of galvanic effect between the nodule structure and the matrix, and barrier effect of the nodule structure.
