Abstract: The AlCoTi amorphous coating was fabricated onto AZ91 magnesium alloy substrate by using high velocity arc spraying process. The microstructure, mechanical properties, wear and electrochemical corrosion behaviours of the coatings were studied. The coating shows a typical laminar morphology with compact structure and a good combination with the substrate. The porosity of the coating is about 1.63%. The microstructure of the coating consists of amorphous phase, α-Al and Al₃Ti nanocrystalline phases. The coating displays higher microhardness and better excellent wear resistance than AZ91 alloy. The microhardness of the coating is about 511.3 HV_0.1, which is much higher than the AZ91 magnesium alloy (62 HV_0.1). The relative wear resistance of the AlCoTi amorphous coating is about 3.9 times that of AZ91 magnesium alloy under the same wear circumstances. The main failure mechanism of the coating is brittle spalling. In 0.6 mol/L NaCl solution, the AlCoTi amorphous coating displays excellent corrosion resistance. The corrosion potential, current density and charge transfer resistance of the coating are －0.696 V, 0.741 8 μA/cm² and 33 660 Ω·cm², respectively, while that of the magnesium alloy is －1.392 V, 769.3 μA/cm² and 1 914 Ω·cm², respectively. This study provides a low-cost, high-quality and efficient remanufacturing protective coating for magnesium alloy by analyzing the electrochemical corrosion properties and microhardness compared with other coatings.

Key words: magnesium alloy, Al-based amorphous coating, corrosion resistance, friction and wear, remanufacturing