Some people may misunderstand what you mean by passivation, passivation refers to the metal in a certain atmosphere due to the production of a layer of dense oxide protective film on the surface, so that the metal is protected from continued corrosion, and this oxide film is the new substance produced in this change. So it's a chemical change. Common metals that cause passivation are aluminum and iron. Aluminum in passivation produces atomic crystal alumina film, this structure is relatively stable, does not react with sulfuric acid, hydrochloric acid and so on.
When iron is passivated, it is also an oxide film, but the oxide structure of iron is not clear to me.