methods of reducing an initial cross - sectional area of a hole in a component to a predetermined cross - sectional area including preparing a composition comprising at least an aluminum alloy with a melting temperature higher than aluminum , applying the composition to an interior surface of the hole , and then heating the component to cause a metal within the component to diffuse from the component into the composition and react with the aluminum alloy in the composition to form a coating on the interior surface of the hole . the heating step is performed to selectively modify the initial cross - sectional area of the hole and thereby directly attain the predetermined cross - sectional area thereof .