Influence of surface chemistry on the formation of crystalline hydroxide coatings on Mg alloys in liquid water and steam systems

• A steam treatment was employed to provide protective coatings to Mg-alloys.
• The steam treatment was conducted in stainless steel autoclaves at 150 °C for 3 h.
• The formation mechanism of the steam coatings on various Mg-alloys was explored.
• Steam is more favourable than liquid water regarding to coating properties.
• Alloying elements also influence coatings properties.