Anodic oxide coatings and methods for forming anodic oxide coatings on metal alloy substrates are disclosed. Methods involve post-anodizing processes that improve the appearance of the anodic oxide coating or increase the strength of the underlying metal alloy substrates. In some embodiments, a diffusion promoting process is used to promote diffusion of one or more types of alloying elements enriched at an interface between the anodic oxide coating and the metal alloy substrate away from the interface. The diffusion promoting process can increase an adhesion strength of the anodic oxide film to the metal alloy substrate and reduce an amount of discoloration due to the enriched alloying elements. In some embodiments, a post-anodizing age hardening process is used to increase the strength of the metal alloy substrate and to improve cosmetics of the anodic oxide coatings.