Kinetics and mechanism of multilayer Mg-Al intermetallic compound coating formation of magnesium alloy by AlCl3-NaCl molten salt bath treatment

► A multilayered coating is fabricated on Mg alloy with molten salt surface treatment. ► The coating consists of δ, α solid-solution and γ, ε, β compound layers. ► A model describing the formation of a multilayered structure is exhibited.