The passivation mechanism can be mainly explained by the Film Theory, that is, it is believed that the passivation is due to the interaction of the magnesium alloy with the oxidizing medium, a very thin, dense, and good-covering passivation film can be formed on the surface of the magnesium alloy. This film exists as a separate phase, and it is usually a compound of oxygen and magnesium alloy. It plays the role of completely separating the magnesium alloy from the corrosive medium, preventing the magnesium alloy from directly contacting the corrosive medium, so that the magnesium alloy basically stops dissolving and forming a passive state to achieve the effect of preventing corrosion.