Coated article and method for repairing a coated surface

In a method for repairing a surface portion of an article that comprises a substrate of a Ni base superalloy, and a metallic environmental resistant coating including Al on the substrate, the coating including a coating outer portion bonded with the substrate through a coating diffusion zone that is integral with the substrate and that includes at least one undesirable feature that includes Al in an amount detrimental to repair of the surface portion, the steps of:

• removing the coating outer portion to expose a surface of the coating diffusion zone;
• heating the substrate and the diffusion zone in a non-oxidizing atmosphere at a temperature in the range of about 1900–2000° F. and for a time in the range of about 4–8 hours sufficient to result, at least in the exposed surface of the diffusion zone and in a portion of the diffusion zone beneath the exposed surface, at least in one of dissolution into the diffusion of at least a portion of at least one detrimental element of the undesirable feature away from the exposed surface and toward and into the substrate, to provide a replacement surface portion with a level or the at least one undesirable feature below the amount;
• and then,
• repairing the replacement surface portion including applying a metallic replacement coating outer portion that includes Al to the replacement surface portion;
• the application of the metallic replacement coating outer portion including heating to provide, in sequence from outwardly toward the substrate, a replacement coating outer portion including Al, an outer diffusion zone including Al and integral with the replacement coating outer portion, and an inner modified portion of the substrate integral with the outer diffusion zone and with the substrate.