Abstract: A diffusion barrier coating includes, in an exemplary embodiment, a composition selected from the group consisting of a solid-solution alloy comprising rhenium and ruthenium wherein the ruthenium comprises about 50 atom % or less of the composition and where a total amount of rhenium and ruthenium is greater than 70 atom %; an intermetallic compound including at least one of Ru(TaAl) and Ru2TaAl, where Ru(TaAl) has a B2 structure and Ru2TaAl has a Heusler structure; and an oxide dispersed in a metallic matrix wherein greater than about 50 volume percent of the matrix comprises the oxide.

Abstract: A shell mold for casting molten material to form an article is described. The mold includes a shell for containing the molten material, formed from at least one of yttrium silicates, zirconium silicates, hafnium silicates, and rare earth silicates. The mold also includes a facecoat disposed on an inner surface of the shell that contacts the molten material. The facecoat can be made from the materials described above. A method of casting a niobium-silicide article is also described, using the shell mold described herein. A method of making the ceramic shell mold is described as well, along with a slurry composition used in the manufacture of the shell mold.

Abstract: A method for removing an oxide material from a crack in a substrate, the method includes: applying a slurry paste comprising a fluoride salt to the crack; heating the slurry paste and the crack to at least a melting point of the fluoride salt to form a reaction product; and removing the reaction product.

Abstract: The present invention provides a method for forming a refractory metal-intermetallic composite. The method includes providing a first powder comprising a refractory metal suitable for forming a metal phase; providing a second powder comprising a silicide precursor suitable for forming an intermetallic phase; blending the first powder and the second powder to form a powder blend; consolidating and mechanically deforming the powder blend at a first temperature; and reacting the powder blend at a second temperature to form the metal phase and the intermetallic phase of the refractory metal-intermetallic composite, wherein the second temperature is higher than the first temperature.

Abstract: Non-destructive systems and methods for temperature measurements are described so that the remaining operational life and accumulated damage of high temperature gas turbine components can be assessed. Alloy-based witness coupons and diffusion couple witness coupons are attached to, or directly applied onto, high temperature components so that they experience the same high temperature operation and shut down as the components themselves. The witness coupons are later removed from the components and analyzed, or are analyzed on the component, to determine the change to their microstructure, metallurgy, and/or diffusion characteristics. Since the time each component spends in operation is known, the operating temperatures of the components can be back-calculated from the microstructural, metallurgical, and/or diffusion characteristic changes of the witness coupons. Therefrom, the remaining operational life of the component can be assessed, as can the accumulated damage to the component.