Abstract: An effective cyanide free solution and process for removing gold-nickel braze alloys from superalloy parts are described. The solution contains about 50% nitric acid with intentional additions of materials which ionize to provide chloride ions, sulfate ions, and metal ions in specific concentrations.

Abstract: An improved apparatus for feeding uniform controlled amounts of powder is provided. The apparatus includes a nozzle, a powder delivery tube which communicates the nozzle with the powder feed apparatus and a vibrator assembly. The vibrator assembly drives a drive rod located within the powder feed tube so that a constant powder flow rate is insured.

Abstract: Apparatus and methods for depositing a coating on a substrate are disclosed. Cathode sputtering techniques for rapidly depositing a relatively thick coating, of controllable and variable composition using multiple cathodes on a substrate having a complex geometry are developed. The apparatus employed includes a sputtering chamber formed between a center, post cathode, a hollow cylindrical cathode and supplemental cathode targets of a different composition.

Abstract: A method is described for increasing the impact properties of dense silicon nitride articles. The method includes the application of a slurry composed predominately of silicon powder to the surface of the dense silicon nitride article. The slurry coated article is then nitrided at an elevated temperature to partially convert the silicon powder to silicon nitride and to bond the particles together and to the substrate. About 15 to 45 volume percent of the silicon powder is not converted to silicon nitride but remains as elemental silicon.

Abstract: Composite ceramic shell molds for investment casting and subsequent directional solidification of nickel and cobalt base superalloys is described. The composite ceramic shell mold is composed of an inner component having an alumina content of at least 80 percent and an average thickness of about ten mils and an outer layer composed predominantly of zircon having a thickness of from 0.1 to 0.4 inches. The alumina component of the shell mold is wet by the superalloy material and this wetting action is believed to cause the substantial elimination of a surface defect problem known as chain porosity. The zircon component of the shell mold had desirable mechanical properties and may easily be removed from the solidified casting. The alumina and zircon components are bonded together in such a fashion that they will not separate during the casting process.

Abstract: A method is disclosed for the nondestructive examination of coated gas turbine components after service. An electrolytic polishing technique is used to uniformly remove the coating from a portion of the component. An electrolytic etching process is then used to preferentially remove a portion of the underlying substrate so as to leave the microstructure in relief. A metallographic examination may then be made to determine if the part is suitable for reuse. Apparatus for conducting the previously described method is also prevented.

Abstract: A series of superalloy compositions are described, which when processed according to a described processing sequence, produce homogeneous superalloy articles which contain an exceptionally high amount of the gamma prime phase. These alloys contain large amounts of aluminum and chromium and hence are quite oxidation resistant. The processing sequence includes rapid solidification to suppress the formation of the low melting eutectic phases which would otherwise occur.

Abstract: A specific composition range and process sequence are described for the production of single crystal superalloy articles which have an exceptional combination of high temperature mechanical properties and resistance to oxidation and hot corrosion. The nominal composition is 5.2% Cr, 5.4% Al, 1.1% Ti, 2.0% Mo, 4.9% W, 6.4% Ta, 3% Re, 0.4% V, balance nickel. Material of this composition is cast and solidified in single crystal form and heat treated to produce an optimum microstructure.

Abstract: A fushion welded surfacing process for use with crack prone substrates is described. The process involves the application of an intermediate layer of crack resistant alloy by fusion welding followed by the application of the desired final surfacing alloy by fusion welding. The intermediate layer is an age hardenable nickel superalloy to which intentional additions of manganese have been made. The final surfacing alloy may be of the hardfacing type or may be of a type which imparts corrosion and oxidation resistance to the underlying article.

Abstract: There are described MCrAlY type coating alloys having improved hot corrosion resistance, especially to sulfur and/or halide bearing compounds. In particular, improved hot corrosion resistance is achieved by the inclusion of about 1 to 12 weight percent titanium in the MCrAlY alloy composition.

Abstract: Silicon nitride coated carbon fibers and composite materials incorporating these fibers are disclosed. The silicon nitride coating provides electrical insulation and improved resistance to environmental degradation. The resultant coated fibers may be embedded in organic or metal matrices to form composite materials.

Abstract: A class of age hardenable nickel base alloys for use as filler wires in fusion welding superalloys is described. The alloys contain manganese in levels of from about 0.5 to 3 percent to greatly reduce the incidence of heat-affected zone cracking in the metal being welded. The weld filler alloys also contain significant amounts of aluminum, titanium, tantalum, and columbium, and therefore the resultant welds can be age hardened to relatively high strength levels.

Abstract: Photon absorbing surfaces which are effective over a broad band of photon energies are described. These surfaces consist of a two-phase material with a protruding second phase whose dimensions are on the order of microns. Photons are absorbed by multiple reflections within the region of the protruding phase. The surfaces are produced by directional solidification of eutectic compositions to produce aligned second phase microstructures within a metallic matrix. The matrix material is then selectively removed to expose the second phase material.

Abstract: Nickel base superalloy single crystal articles formed of a particular compositon and heat treated are described as is the process employed. The resultant articles are substantially free from the grain boundary strengtheners such as carbon, boron, and zirconium and contain only a limited amount of cobalt. As a result of the alloy composition, the alloys have a high incipient melting temperature. The heat treatment process homogenizes the micro-structure, and refines the gamma prime morphology.

Abstract: This invention concerns a method for controlling the microstructure of directionally solidified eutectic articles and the article produced thereby. The method is particularly appropriate for the production of articles such as turbine blades which require different mechanical properties in different areas of the article. The microstructure is controlled by varying the directional solidification conditions during the casting process.

Abstract: The method and apparatus of the present invention substantially reduce the incidence of cracking, flaking, bulging and other mold defects which originate during the drying step of the investment mold formation process. Drying is conducted under conditions which enhance uniformity of drying and which preclude harmful increases in pattern temperature resulting from changes in the moisture removal kinetics of the slurry layer. In particular, during the drying process, drying air of different quality is provided during the different stages of moisture removal from the slurry layer.

Abstract: A stabilization heat treatment for a class of wrought cobalt alloys is described. The heat treatment produces a useful combination of initial ductility, so as to permit fabrication of intricate parts, and adequate ductility even after long term exposure at elevated temperatures as, for example, that exposure encountered in gas turbine service. The heat treatment consists of a solution treatment performed at elevated temperatures followed by two aging steps at lower temperatures. The nominal alloy composition is 22.5% chromium, 4.25% aluminum, 15% (nickel+iron), 3% (tantalum+columbium), 10% (tungsten+molybdenum), 1.25% hafnium, 0.05% yttrium, 0.35% carbon, balance essentially cobalt.

Abstract: A nickel base superalloy having a composition which provides a desirable combination of good oxidation and corrosion resistance and hot hardness is described. The alloy contains 21-25% Cr, 4.5-7% Al, 4-10% W, 2.5-7% Ta, 0.5-0.15% Y and 0.1-0.3% C. This alloy is useful as a blade tip element in a composite gas turbine blade.

Abstract: A high ductility, high strength, moderate conductivity aluminum conductor article and process for making the article are described. The article is a conductor of elongated geometry containing a low volume fraction of intermetallic fibers which are aligned parallel with the major axis of the conductor. The surrounding matrix is aluminum of at least commercial purity to which from 0.5 to 1.5% copper has been added. The fabrication process involves the coupled solidification of eutectic and slightly proeutectic compositions to produce a fibrous microstructure, followed by mechanical working. The ductility of the finished article will exceed about 5%. The final properties may be varied by heat treatments. The broad composition is 1.0-2.0% Co, 0.5-1.5% Cu, balance aluminum.

Abstract: A method for producing a cooled sputtering target assembly is described. The resultant target is also described. The material to be sputtered is provided in the form of powder which is hot isostatically pressed in a toroidal metallic container under conditions which promote compaction and bonding of the powder particles to form a fully dense material. The container is then partially removed from the target material except for a remnant around the outer surface. A cooling jacket is then fabricated and attached to the remnant of the container.