Preparation and characterization of duplex PEO/MoC coatings on Mg-Li alloy

► The duplex PEO/MoC coating on the surface of Mg-Li alloy has been fabricated by using a combination of PEO and chemical conversion. ► The duplex PEO/MoC coating was composed of crystalline NaMgF3, Mg2SiO4, MoO3 and MgO. ► The formation mechanism of PEO/MoC coating was proposed.