Influence of alloying elements and microstructure on the formation of hydrotalcite film on Mg alloys

•A hydrotalcite film has been formed on Al-free Mg alloys by in situ growth method.•The influence of alloying elements on the composition of the films is discussed.•The role of microstructure in the formation of hydrotalcite film is illustrated.

The influence of alloying elements and microstructure of Mg substrates on the formation of hydrotalcite film has been investigated. It is found that the two-step process is also available for the pure Mg and other alloys after modification. A small amount of Zn does not impact the composition of the hydrotalcite film much; whereas the highly active rare earth (RE) affects the constituents of the precursor film as well as the final film on WE54 alloy significantly. The microstructure impacts the initial nucleation and the film morphology depending on the size and chemical activity of the intermetallic particles.