Abstract: The oxidation resistance of a superalloy casting such as an equiaxed, directionally solidified, or single crystal casting, is improved by melting, pouring, or casting the alloy so as to react with a magnesium or calcium-bearing ceramic material. Magnesium or calcium is introduced into the alloy through a controlled reaction between the alloy and the magnesium or calcium-bearing ceramic material.

Abstract: A method of making a composite casting wherein a casting mold is provided having a melt-receiving mold cavity and a preformed metallic or intermetallic insert located in a predetermined position in the mold cavity. A melt is introduced into the mold cavity about the insert and is solidified to provide a composite casting having one or more interfaces between the insert, or an insert positioning member, and cast/solidified metal about the insert. The interface is exposed on or communicates with an exterior surface of the composite casting. After separation from the mold, the composite casting is subjected to a sealing operation to gas-tight seal the interface(s) at the exterior casting surface. For example, the interface can be sealed by providing fused material at the interface.

Abstract: In a method of making a load-bearing article by spray casting a molten metal onto a metal substrate, the substrate surface receiving the spray cast deposit is treated by vacuum cleaning, boronizing and/or knurling to enhance the structural integrity of the diffusion bond joint subsequently formed between the spray cast deposit and the substrate in sustaining a load across the joint without premature joint failure.

Abstract: The method of making a composite article of different metal portions by spraying molten metal on the surface of a solid metal member that has been cleaned and preheated in a controlled atmosphere at low pressure. The molten metal is sprayed on the surface of the solid metal member, preferably by plasma jet spraying. It is rapidly solidified to be adherent to the surface of the solid metal member to form a composite preform. The composite preform is cooled at a rate sufficiently low to reduce residual stresses and then hot pressed to eliminate voids in the sprayed metal portion and metallurgically bonded to the surface of the solid member.

Abstract: A method of making a casting wherein a molten alloy is introduced into a mold cavity at an initial mold fill rate to partially fill the mold cavity while the mold cavity resides in a casting chamber. A solidification front is propagated through the molten alloy to provide a solidification rate. The remaining molten alloy is introduced into the mold at a second mold fill rate less than the first mold fill rate as the front propagates through the molten alloy. The second fill rate is controlled to correspond or be matched generally to the solidification rate of the molten alloy in the mold cavity.

Abstract: A high melting point and/or low ductility metal or alloy is investment cast in a refractory mold including a facecoat layer and a plurality of back-up layers wherein at least one back-up layer is a relatively weak, sacrificial layer. This latter layer is crushed as necessary as the casting cools below its ductile-to-brittle transition temperature to avoid hot tearing or cracking of the solidified metal or alloy during cooling in the mold.

Abstract: A method of making a casting having an internal passage involves the steps of forming a core having an external surface configured to form the passage in the casting and having a plurality of integrally formed protrusions extending from the external surface at stressed regions thereof (e.g., thermally stressed regions) prone to be distorted from a master core configuration, and positioning the core in a pattern molding cavity by engagement of the protrusions with rigid walls defining the molding cavity such that the core is conformed substantially to a predetermined and/or empirically determined relationship between the master core configuration and the molding cavity as if the core corresponded to the master core configuration. A fugitive pattern corresponding to the casting to be formed is then molded about the external surface of the core while the core is supported in the aforementioned relationship relative to the molding cavity, whereby the wall thickness of the pattern is controlled about the core.

Abstract: Titanium based and nickel based castings are made by casting a suitable melt having a relatively low melt superheat into a mold cavity defined by one or more low carbon steel or titanium mold members where the melt solidifies to form the desired casting. The melt super-heat is limited so as not to exceed about 150.degree. F. above the liquidus temperature of the particular melt being cast. For a steel mold, one or more titanium melt inlet-forming members are provided for cooperating with the steel mold members to form an melt ingate that communicates to the mold cavity for supplying the melt thereto in a manner to avoid harmful iron contamination of the melt during casting. The mold body-to-mold cavity volume ratio is controlled between 10:1 to 0.5:1 to minimize casting surface defects and mold wear/damage.

Abstract: A TiAl alloy base melt including at least one of Cr, C, Ga, Mo, Mn, Nb, Ni Si, Ta, V and W and at least about 0.5 volume % boride dispersoids is investment cast to form a crack-free, net or near-net shape article having a gamma TiAl intermetallic-containing matrix with a grain size of about 10 to about 250 microns as a result of the presence of the boride dispersoids in the melt. As hot isostatically pressed and heat treated to provide an equiaxed grain structure, the article exhibits improved strength.

Abstract: In making a dual alloy gas turbine rotor, a plurality of superalloy components are formed to include an airfoil having a directionally solidified columnar grain structure or a single crystal grain structure. A boron-bearing melting point depressant material is applied to the inner surface and a side surface of the components. The components are arranged side-by-side in an annular array with the first side surface of one component juxtaposed to the second side surface of an adjacent component and with the inner surfaces defining a spray-receiving surface. The airfoils extend in a radial axis or direction of the array while the spray-receiving surface extends in a circumferential direction of the article. A sealing member is positioned adjacent an axial end of the array of the components to close off that end and form a spray-receiving cavity. Boron-bearing melting point depressant material is provided between the sealing member and the end of the array.

Abstract: A method of joining metal materials by spraying molten metal into a cavity between the articles to be joined. Prior to deposition of the metal, the surface of the cavity is cleaned and the articles to be joined are preheated. Subsequent to deposition of the metal within the cavity, the joined articles are cooled at a rate that precludes damage due to thermal effects and the deposited metal is consolidated in the cavity by hot pressing.

Abstract: A method of making a composite casting wherein a casting mold is provided for receiving a melt and a preformed metallic or intermetallic insert is positioned in the mold cavity. The preformed insert includes a working portion for incorporation in the casting and gas seal-forming means located at a region of the insert at least outboard of the insert portion. A melt is introduced into the mold about the insert and is then solidified to provide a composite casting having the insert working portion disposed in the solidified melt and as-cast gas seal regions located outboard of the insert working portion in the casting. The casting is then subjected to elevated temperature and isostatic gas pressure conditions wherein the as-cast gas seal regions are effective to inhibit gas penetration between the insert working portion and the solidified melt therearound so as to permit formation of a sound, void-free metallurgical bond therebetween.

Abstract: A chemical vapor deposition (CVD) method utilizing an apparatus comprising a reactor having a coating chamber at elevated temperature, means for supporting substrates to be coated at different zones in the coating chamber, and means for supplying a gaseous reactant stream to the chamber for distribution to the coating zones in a manner that the stream is heated to substantially different temperatures at different coating zones. Reactivity-altering material is disposed at the coating zones for contact by the reactant stream supplied thereto before the reactant stream contacts a substrate at the zones. The reactivity-altering material includes a composition that differs between coating zones in dependence on the reactant stream temperatures at the coating zones as necessary to alter the reactivity of the reactant (i.e., activity of a particular chemical specie of the reactant stream) stream at the coating zones in a manner to provide substantially the same reactant reactivity at all coating zones.

Abstract: Chemical vapor deposition apparatus comprises a reactor having a chamber with a coating region for coating a substrate and an exhaust region communicating with the coating region. The coating region includes an inlet for introduction of a gaseous reactant stream to pass over the substrate to react therewith to form a coating thereon and a spent gas stream. The exhaust region includes an outlet for exhausting the spent gas stream from the coating region. The substrate is supported in the coating region and heated to an elevated reaction temperature by suitable support means and heating means. A condensing assembly is disposed in the exhaust region for condensing excess, unreacted gaseous reactant from the spent gas stream before entry into the outlet. The condensing assembly includes a high surface area, apertured structure disposed in the exhaust region where the temperature of the spent gas stream is sufficiently reduced to condense excess, unreacted gaseous reactant therefrom.

Abstract: A plastic model pattern indicative of the desired completed pattern having prescribed dimensional tolerances and surface finish characteristics is encased within a Type I material which may be a soluble wax or low melting point material, and subsequently leached from the Type I material to define a cavity corresponding to the dimensional characteristics of the plastic model pattern. A Type II material, such as an insoluble wax or high melting point material, may then be injected into the cavity to recreate the plastic model pattern without the use of any plastics materials, to avoid potentially mold deteriorating expansion of such plastics materials. The mold form of Type I material may then be removed by leaching, melting or the like to reveal the completed expendable pattern usable in a lost wax mold forming process. An injection apparatus and die structure is advantageously utilized in conjunction with the process to achieve high production quality and insure proper formation of the expendable pattern.

Abstract: A casting mold includes a melt-receiving mold cavity having a preformed metallic or intermetallic insert suspended therein by at least one elongated, slender suspension member fixed at one end to the insert and at another end to the mold. A melt of metallic or intermetallic material is introduced into the mold cavity about the suspended insert and the suspension member and is solidified to form a composite casting The casting is subjected to elevated temperature/elevated isostatic gas pressure conditions wherein the interface between the suspension member and the cast melt is effective to inhibit gas penetration between the insert and cast melt, thereby allowing a sound, void-free, contamination-free metallurgical bond to be produced between the insert and the cast melt.

Abstract: A casting mold includes a melt-receiving mold cavity having a preformed metallic or intermetallic insert suspended therein by one or more first elongated, slender suspension members fixed at one end to the insert and at another end to the mold to locate the insert in a first direction in the mold and by one or more second elongated, slender suspension members fixed at one end to the insert and abutting the mold at another end to locate the insert in a second direction in the mold. A melt of metallic or intermetallic material is introduced into the mold cavity about the suspended insert and the suspension members and is solidified to form a composite casting.

Abstract: In the melting of one or successive alloy charges including one or more volatile alloying elements, each alloy charge is melted in a melting vessel under an inert gas partial pressure effective to reduce volatilization, migration and condensation of the volatile alloying elements and build-up of condensate deposits of the volatile elements on cool regions of the melting vessel and melting chamber where the deposits constitute inclusion precursors that can eventually enter successive charges melted in the vessel. Wetting of the crucible by the melt is also reduced by the gas partial pressure. The incidence of inclusions found in castings produced from the successive melts is thereby reduced.

Abstract: A novel method of making a ceramic core for use in casting a metal component includes freezing a ceramic slurry comprising a ceramic powder filler, a freezable liquid and a gelling agent in a mold to form a frozen core shaped body. The frozen core shaped body is removed from the mold and thawed to room temperature. A high viscosity gel is provided in the core shaped body at room temperature that is strong enough to retain the core shape until the body can be fired to form a porous, sintered ceramic core. The gel present at room temperature may be formed as the ceramic slurry is cooled in the mold cavity to form the frozen article shaped body and/or as the frozen core shaped body is thawed to room temperature.

Abstract: A reinforced ceramic investment casting shell mold and method of making such mold. The ceramic investment casting shell mold includes alternate, repeating layers of a ceramic material and a ceramic stucco defining an overall thickness of the shell mold. A fibrous reinforcing material is disposed in the alternate, repeating layers at an intermediate thickness of the shell mold. The fibrous reinforcing material has high tensile strength at elevated temperature and a coefficient of thermal expansion that is less than the coefficient of thermal expansion of the ceramic material and the ceramic stucco. The fibrous reinforcing material is preferably woven into a twisted yarn and disposed in a generally spiral configuration.