Abstract: An apparatus for incorporating an elemental component in gaseous form into a molten metal is described. The apparatus comprises a container for holding the molten metal; means for cooling the container; heating means for maintaining the metal in the molten state; and a canopy which covers the top of the container. The apparatus also includes at least one aperture through which a desired gaseous material can be fed from a gas source. A related method for incorporating an elemental component in gaseous form into a molten metal is also described. The method includes the step of providing the metal in a container apparatus as described above, and feeding the gaseous elemental component from a gas source into the container, while maintaining the metal in the molten state. Articles prepared by such a method are also disclosed, as well as niobium base composites which comprise niobium, silicon, and nitrogen.

Abstract: A rare earth-based core for use in the casting of a reactive metal is described. The core contains a ceramic composition which includes at least about 10% by weight of monoclinic rare earth aluminate (RE4Al2O9), wherein RE represents at least one rare earth element; and at least about 10% by weight of at least one free rare earth oxide. The ceramic phase of the composition may include a microstructure which comprises a multitude of substantially spherical pores which are formed as a result of the removal of aluminum metal from the core composition during a heat treatment step. Additional embodiments relate to a method for the fabrication of a ceramic core, employing a rare earth oxide, aluminum metal, and a binder. Methods for removing cores from a cast part are also described.

Abstract: A coating suitable for use as protective oxide-forming coatings on Nb-based substrates, and particularly monolithic niobium-based alloys, exposed to high temperatures and oxidative environments. The coating contains aluminum, may further contain silicon, and optionally contains niobium, titanium, hafnium, and/or chromium, which in combination form one or more intermetallic phases that promote the formation of a slow-growing oxide scale. The intermetallic phases may be M(Al,Si)3, M5(Al,Si)3, and/or M3Si5Al2 where M is niobium, titanium, hafnium, and/or chromium.

Abstract: Nb—Si based alloy articles comprising a Nb—Si based alloy upon which is disposed an environmentally-resistant coating are described. They include a coating comprising at least one phase selected from the group consisting of M(Al,Si)3, M5(Al,Si)3, and M3Si5Al2, wherein M is one or more of Nb, Ti, Hf, Cr. Such coating can improve the environmental (e.g., in oxidation-promoting environments) resistance of a Nb—Si based alloy and alloy articles. Methods for preparing these articles are described as well.

Abstract: Methods for making a reinforced refractory crucible for melting titanium alloys including providing a form, applying a facecoat to the form, the facecoat having at least one facecoat layer, applying a backing about the facecoat, the backing having at least one backing layer, applying at least one reinforcing element to at least a portion of the facecoat layer, the backing layer, or a combination thereof where the reinforcing element includes at least one composition selected from ceramic compositions, metallic compositions, and combinations thereof.

Abstract: Methods for making refractory crucibles for melting titanium alloys including providing a form, applying a facecoat to the form, and applying a backing to the facecoat where the facecoat has at least one facecoat layer including an oxide selected from the group consisting of scandium oxide, yttrium oxide, hafnium oxide, a lanthanide series oxide, and combinations thereof and where the backing to the facecoat has a thickness ratio of from about 6.5:1 to about 20:1.

Abstract: Crucibles for melting titanium alloys having a facecoat including at least one facecoat layer containing an oxide selected from scandium oxide, yttrium oxide, hafnium oxide, a lanthanide series oxide, and combinations thereof, and a backing including at least one backing layer where the crucible has a backing to facecoat thickness ratio of from about 6.5:1 to about 20:1.

Abstract: Reinforced crucibles for melting titanium alloys having a facecoat including at least one facecoat layer, a backing including at least one backing layer, and at least one reinforcing element applied to at least a portion of one or more of the facecoat layer, the backing layer, or a combination thereof where the reinforcing element includes at least one composition selected from ceramic compositions, metallic compositions, and combinations thereof.

Abstract: A lamp comprising an arc envelope and a niobium end structure coupled to the arc envelope, and wherein the end structure is shielded from a dosing material disposed within the arc envelope.

Abstract: A lamp is provided with an axially and radially graded structure to reduce the possibility of thermal stresses, cracks, and other defects in the lamp. In one embodiment, a system includes a ceramic lamp having a ceramic arc envelope and an end structure coupled to the ceramic arc envelope, wherein the end structure is graded both axially and radially into a plurality of regions. In another embodiment, a system includes a lamp having a layered end structure with a plurality of layers disposed one over another and that extend in both axial and radial directions relative to an axis of the lamp, wherein the plurality of layers include different materials having different coefficients of thermal expansion, Poisson's ratios, or elastic moduli, or a combination thereof,.

Abstract: A conductive element comprises a metal core and a coating, wherein the coating comprises at least one layer of aluminum, an aluminum alloy, an aluminide, silicon, a silicon alloy, a silicide, and combinations thereof, and wherein the at least one layer has a predetermined thickness. A method of making a conductive element comprises depositing a coating material on a metal core to form a coated metal core and heating the coated metal core to a predetermined temperature to form at least one layer of aluminum, an aluminum alloy, an aluminide, silicon, a silicon alloy, a silicide, and combinations thereof.

Abstract: Articles for use with highly reactive alloys that include a graphite crucible having an interior, and at least a first protective layer applied to the interior of the graphite crucible in which the graphite crucible having the first protective layer is used for melting highly reactive alloys.

Abstract: Methods for reducing carbon contamination when melting highly reactive alloys involving providing a graphite crucible having an interior, applying at least a first protective layer to the interior of the graphite crucible, placing a highly reactive alloy into the crucible having the first protective layer, and melting the highly reactive alloy to obtain a melted alloy having reduced carbon contamination.

Abstract: Niobium silicide articles are described. They include a surface region enriched with at least about 25 atom % germanium, which can enhance the properties of the article. Methods for preparing these articles are described as well. According to one method, an article is formed from a niobium silicide composite material which contains a selected amount of germanium. The article is then heat-treated under conditions sufficient to increase the level of germanium in the surface region to at least about 25 atom %, based on the total composition of the surface region. In another embodiment, a germanium-containing material is applied over a niobium-silicide article, and then diffused into the surface region of the article by way of a heat treatment.

Abstract: In accordance with certain embodiments, the present technique includes a system for sealing a lamp including a thermal shield and a thermally susceptible enclosure disposed adjacent the thermal shield. The thermal shield has a first receptacle adapted to receive a first portion of the lamp. The thermally susceptible enclosure comprises a wall about a second receptacle adapted to receive a second portion of the lamp. The wall has a varying thickness in a desired sealing region between the first and second portions of the lamp.

Abstract: A conductive element comprises a metal core and a coating, wherein the coating comprises at least one layer of aluminum, an aluminum alloy, an aluminide, silicon, a silicon alloy, a silicide, and combinations thereof, and wherein the at least one layer has a predetermined thickness. A method of making a conductive element comprises depositing a coating material on a metal core to form a coated metal core and heating the coated metal core to a predetermined temperature to form at least one layer of aluminum, an aluminum alloy, an aluminide, silicon, a silicon alloy, a silicide, and combinations thereof.

Abstract: A method of fabricating a core for a ceramic shell mold is disclosed. A porous core body is formed from at least about 50% by weight of at least one rare earth metal oxide. The core body is heated under heating conditions sufficient to provide the core with a density of about 35% to about 80% of its theoretical density. The core body is then infiltrated with a liquid colloid or solution of at least one metal oxide compound, e.g., rare earth metal oxides; silica, aluminum oxide, transition metal oxides, and combinations thereof. The infiltrated core body is then heated to sinter the particles without substantially changing the dimensions of the core body. Mold-core assemblies which include such a core body are also described. A description of processes for casting a turbine component, using the core, is also set forth herein.

Abstract: An apparatus for friction stir welding, a weld tool for friction stir welding, and a method for making a weld tool for friction stir welding are presented. The weld tool comprises doped tungsten. A method for manufacturing an article, where the method comprises providing the apparatus for friction stir welding, and the article produced by this method are also presented.

Abstract: An electrically conducting cermet comprises at least one transition metal element dispersed in a matrix of at least one refractory oxide selected from the group consisting of yttria, alumina, garnet, magnesium aluminum oxide, and combinations; wherein an amount of the at least one transition metal element is less than 15 volume percent of the total volume of the cermet. A device comprises the aforementioned electrically conducting cermet.

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.