Improvement of surface corrosion resistance for magnesium alloy by combining thermal spray and cast-infiltration

The present work focuses on a new method combining cast-infiltration with thermal spraying technology to improve the surface corrosion resistance of magnesium alloy. A zinc-based alloy layer was fabricated on the surface of AZ91D magnesium alloy. The microstructure of the layer was characterized by scanning electron microscopy equipped with an energy dispersive X-ray spectroscopy (EDS). The phase constituent of these alloys was identified by X-ray diffractometry (XRD). The analysis results reveal that a zinc-based alloy layer with a thickness of 700 μm can form on the surface of AZ91 alloy matrix. The layer is composed of Mg7Zn3, MgZn and a small amount of α-Mg solid solution. The results indicate that the corrosion-resistance of the specimen with a zinc-based alloy layer is much better than that of the specimen without the layer after being immersed in 5% NaCl solution for 240 h, and the layer is more protective for the AZ91 alloy.