Abstract: A nickel-base gamma-sigma intermetallic matrix composite material suitable for forming gas turbine engine components and structural coatings for such components. The composite material contains, in weight percent, about 20 to 50 chromium, about 0 to 32 molybdenum, and about 0.5 to 7 silicon, with the balance being nickel and incidental impurities. In addition, the composite material may contain aluminum and titanium in amounts of up to about 7 and 3 weight percent, respectively. The resulting intermetallic matrix composite material is characterized by a sigma volume fraction of greater than 30 percent, preferably at least about 50 percent, and may have a dendritic, fibrous or lamellar microstructure. The composite material can be cast to form a component, or deposited by known techniques to form a structural coating on a component.

Abstract: Nb-base alloys that include Ti, Hf, Cr, Al and Si as alloy constituents have a microstructure that includes a metallic solid solution phase and a mixture of intermetallic silicide phases. The metal silicide phases include an M.sub.3 Si silicide, where M comprises Nb, Ti or Hf, and an M.sub.5 (Si, Al).sub.3 silicide, where M comprises Nb, Ti or Hf. These alloys have mechanical properties such as low temperature fracture toughness, high temperature fracture strength, high temperature stress rupture strength and high temperature creep resistance, that meet or exceed those of certain Ni-base superalloys.

Abstract: A method for repairing a blade tip of a turbine blade of a gas turbine engine. The method is particularly directed to replacing the squealer tip (14) of a directionally solidified (DS) or single crystal (SX) turbine blade (10), and can be carried out using a brazing or welding technique. The method generally entails the step of machining the tip (14) to remove any damaged, worn, oxidized or eroded portions thereof sustained by the blade (10) during engine operation. A DS or SX superalloy replacement tip (18) is then placed on the surface generated by the machining operation. If a brazing operation is used, a brazing alloy composition (16) is first applied to the blade tip or replacement tip (18) prior to placement of the replacement tip (18).

Abstract: Methods of making cylindrical structures with cooling channels, such as, for example, combustor/transition pieces for gas turbines having a double wall with a plurality of cooling channels, both axially and, in some cases, circumferential cross-flow passages positioned between the structure's inner member and the outer member to provide cooling air thereto, are disclosed. The cooling channels are formed in the area between the inner member of the structure and the outer member thereof. The passages preferably extend both axially and circumferentially with respect to the direction of flow through the structure. The axial passages extend completely from one end to the other and the circumferential passages extend around the circumference of the structure.

Abstract: A double wall hot gas path part for turbines, such as an airfoil, combustor, duct or shroud, comprises an outer skin and an inner support wall that are metallurgically bonded to one another. The double wall contains integral channels for passage of cooling air adjacent to the skin. The skin may be a metal alloy skin or a microlaminate structure, including microlaminate composite structures. Microlaminate composites typically have a lower density than that of the material used for the support wall, and a simplified internal geometry, which promote weight reductions in the parts and increases in engine operating efficiency.

Abstract: An extension is formed directly on the end of an article by dipping the end into a molten bath of an alloy, followed by withdrawal of the end at a rate sufficient to form the extension. Extensions formed have a microstructure that is continuous and compatible with that of the article. Such microstructures may include epitaxial growth of the extension onto the microstructure of the article. The method establishes a temperature gradient within the article that may be controlled by heating and/or cooling the article during the practice of the method.

Abstract: A method of forming a protective coating of a CrRuAl alloy is provided. The substrate to be coated is first plated with a combination of chromium and ruthenium. Next, the coated substrate is aluminized with fine aluminum powder in an aluminum oxide pack at about 1150.degree. C. The coating formed is resistant to atmospheric attack and protects the substrate.

Abstract: An extension is formed directly on an article by casting a compatible material into a ceramic mold that is attached on an end of the article, followed by cooling of the end under controlled conditions sufficient to cause an integral extension to solidify on the article. A ceramic mold is utilized over the end of the article, with a mold cavity that generally defines the shape of the extension to be formed. The mold may be formed in situ on the mandrel, or preformed and attached to the subject article over the mandrel. Extensions formed by the method of this invention have a microstructure that is continuous and compatible with that of the article. Such microstructures may include epitaxial growth of the extension from the microstructure of the article. The method establishes a temperature gradient within the article during solidification that may be further controlled by auxiliary heating and/or cooling of the article and/or extension during the practice of the method.

Abstract: A combustor/transition piece for a gas turbine including a double walled structure having a plurality of cooling channels, both axially and, in some cases, circumferential cross-flow passages positioned between the structure's inner member and the outer member to provide cooling air thereto, are formed in the area between the inner member of the combustor and the outer member thereof. The passages preferably extend both axially and circumferentially with respect to the direction of flow through the combustor/transition piece. The axial passages extend completely from one end to the other and the circumferential passages extend around the circumference of the combustor/transition piece. The addition of a circumferential cross-flow passage connecting axial flow coolant passages in double wall turbine components can prevent combustor/transition piece part failure due to axial passage inlet blockage without affecting normal, unblocked cooling.

Abstract: Si-Fe-Cr base coating alloys that significantly promote the oxidation resistance of niobium-base alloys and intermetallic materials when deposited and reaction bonded to the niobium-base material. The coating alloys are deposited and then reaction bonded to a niobium-base material to yield an oxidation-resistant coating comprising an interaction layer containing at least one oxidation-resistant Si-Fe-Nb-Cr intermetallic phase.

Abstract: An improved anode assembly for an x-ray tube is described herein. The assembly includes:(a) a target having a central cavity formed therein;(b) a tubular stem for connection to the target to form a target/stem assembly;(c) an insert within the central cavity, shaped to receive a portion of the stem, and comprising a niobium-based alloy; and(d) a rotor body assembly adapted for connection to the target/stem assembly and rotation therewith.X-ray tubes which incorporate such an anode assembly are also described, as are methods for bonding a target to a tubular stem for use in a rotating x-ray tube.

Abstract: An extension is formed directly on an article by dipping a portion or end of the article having an attached integral mandrel into a molten bath of a compatible alloy, followed by withdrawal of the end under controlled conditions sufficient to cause an integral extension to solidify on the article. A ceramic mold is utilized over the dipped end of the article and the integral mandrel with a mold cavity that generally defines the shape of the extension to be formed. The mold may be formed in situ on the mandrel, or preformed and attached to the subject article over the mandrel. The integral mandrel is melted within the mold by dipping the mandrel into the molten alloy. The mandrel acts as a buffer between the molten material and the article while permitting melting of the article end and solidification of the integral extension. Extensions formed by the method of this invention have a microstructure that is continuous and compatible with that of the article.

Abstract: An extension is formed directly on an article by melting a portion or end of the article having an attached integral mandrel within a ceramic mold, followed by cooling of the end under controlled conditions sufficient to cause an integral extension to solidify on the article. A ceramic mold is attached on the end of the article over the integral mandrel with a mold cavity that generally defines the shape of the extension to be formed. The mold may be formed in situ on the mandrel, or preformed and attached to the subject article over the mandrel. Extensions formed by the method of this invention have a microstructure that is continuous and compatible with that of the article. Such microstructures may include epitaxial growth of the extension from the microstructure of the article. The method establishes a temperature gradient within the article during solidification that may be further controlled by auxiliary heating and/or cooling of the article and/or extension during the practice of the method.

Abstract: An extension is formed directly on an article by melting a compatible alloy preform within a ceramic mold, followed by cooling of the end under controlled conditions sufficient to cause an integral extension to solidify on the article. A ceramic mold is attached on the end of the article with a mold cavity that generally defines the shape of the extension to be formed. The mold may be formed in situ on a removable mandrel, or preformed and attached to the subject article. Extensions formed by the method of this invention have a microstructure that is continuous and compatible with that of the article. Such microstructures may include epitaxial growth of the extension from the microstructure of the article. The method establishes a temperature gradient within the article during solidification that may be further controlled by auxiliary heating and/or cooling of the article and/or extension during the practice of the method.

Abstract: An improved high performance x-ray system having a rotating anode therein which includes an improved target/stem assembly comprising a metallic target and a large bore, thin-walled tubular metal stem which, when connected to a rotor body assembly, provides a rotating x-ray tube anode assembly is disclosed. An insert of an alloy, for example, tantalum alloy, is placed between the target layer and the large bore, thin-walled tubular niobium or niobium alloy stem and then bonded thereto to produce a composite x-ray tube target/stem assembly. The target/stem assembly is then connected to a rotor body assembly by fasteners, preferably threaded, to produce a rotating anode assembly having high bond strength that provides acceptable balance during x-ray tube operations.

Abstract: A method for making double-wall airfoil for applications such as the blades and vanes of gas turbine engines by depositing an airfoil skin over an inner support wall which is separately formed and contains channels filled by a channel filling means. The channel filling means is removed thereby forming integral channels within the double-wall for circulating a cooling gas adjacent to the airfoil skin. The airfoil skin deposited may be a metal alloy skin or a microlaminate structure, including microlaminate composite structures.