Patent ID: 8795845

Claim:
An integrated coating structure comprising: (a) a substrate alloy comprising metal elements; and (b) a coating integrated with a surface of the substrate alloy, the coating comprising: a first element that is a metal element of the substrate alloy, a second element characterized in that it is capable of reacting with the first element to form an intermetallic compound and a third element that is a metal or metalloid; wherein the coating has: (i) a corrosion resistant layer comprising a first intermetallic compound comprising the first and second elements, the first intermetallic compound having a defect structure comprising constitutional vacancies for atoms of the second element, wherein the constitutional vacancies allow for the enhanced diffusion of the atoms of the second element through the first intermetallic compound relative to their diffusion through a diffusion barrier layer; and (ii) the diffusion barrier underlying the corrosion resistant layer and integrated into the surface of the substrate alloy, the diffusion barrier comprising a second intermetallic compound comprising the first element and the third element, the second intermetallic compound having a structure comprising fewer constitutional vacancies for atoms of the second element than the defect structure of the first intermetallic compound, such that the diffusion barrier hinders the diffusion of the atoms of the second element through the diffusion barrier relative to their diffusion through the corrosion resistant layer.