Preparation of Al-based Amorphous/Nanocrystalline Composite Coating on Mg-based Alloys Precipitated by Arc Spraying Process

The Al-based amorphous and nanocrystalline composite coatings with the composition of Al-Ni-Y-Co and Al-Ni-Mm-Fe were prepared on AZ91 Mg-based alloys by high velocity arc spraying technique(HVAS).The structure character of the coatings indicates that coatings contain the mixture of amorphous phases and crystalline and there are both less than 2%porosity.The electrochemical tests of the coatings and the substrate were studied.The coatings show the passivation ability during polarization,but AZ91 Mg-based alloys show little passivation.The corrosion current density of the coatings is lower than that of AZ91 Mg-based alloys.The results show that the coatings have an excellent corrosion resistance for AZ91 Mg-based alloys in 5 wt%NaCl solution.