Search Results for aluminide alloy

This article reviews the bulk deformation processes for various aluminide and silicide intermetallic alloys with emphasis on the gamma titanium aluminide alloys. It summarizes the understanding of microstructure evolution and fracture behavior during thermomechanical processing of the gamma aluminides with particular reference to production scaleable techniques, including vacuum arc and cold-hearth melting, isothermal forging, conventional hot forging, and extrusion. The selection and design of manufacturing methods, in the context of processing-cost trade-offs for gamma titanium aluminide alloys, are also discussed.

Alloys based on ordered intermetallic compounds constitute a unique class of metallic material that form long-range ordered crystal structures below a critical temperature. Aluminides, a unique class of ordered intermetallic materials, possesses many attributes like low densities, high melting points, and good high-temperature strength that make them an attractive material for high-temperature structural application. This article discusses the properties, chemical composition, corrosion resistance, processing, fabrication, alloying effects and crystallographic data of nickel aluminides (Ni3Al and NiAl), iron aluminides (Fe3Al and FeAl) and titanium aluminides (alpha-2 alloys, orthorhombic alloys, and gamma alloys).

Ordered intermetallic compounds based on aluminides and silicides constitute a unique class of metallic materials that have promising physical and mechanical properties for structural applications at elevated temperatures. This article provides useful information on mechanical and metallurgical properties, material processing and fabrication, structural applications, mechanical behavior, environmental embrittlement, alloying effects, and crystal structure of aluminides of nickel, iron, titanium, and silicides. It describes the cleavage and intergranular fracture in trialuminides.

Titanium alloys are forged into a variety of shapes and types of forgings, with a broad range of final part forging design criteria based on the intended end-product application. This article begins with a discussion on the classes of titanium alloys, their forgeability, and factors affecting forgeability. It describes the forging techniques, equipment, and common processing elements associated with titanium alloy forging. The processing elements include the preparation of forging stock, preheating of the stock, die heating, lubrication, forging process, trimming and repair, cleaning, heat treatment, and inspection. The article presents a discussion on titanium alloy precision forgings and concludes with information on the forging of advanced titanium materials and titanium aluminides.

Metalworking is one of the three major technologies used to fabricate metal products. This article tabulates the classification of metal forming processes. It discusses different types of metalworking equipment, including rolling mills, ring-rolling machines, and thread-rolling and surface-rolling machines. The article outlines the significant characteristics of pressing-type machines: load and energy characteristics, time-related characteristics, and accuracy characteristics. It summarizes different specialized processes such as advanced roll-forming methods, equal-channel angular extrusion, incremental forging, and microforming. The article describes the thermomechanical processing of nickel- and titanium-base alloys and concludes with information on the advancements in process simulation.

Titanium and its alloys are used in various applications owing to its high strength, stiffness, good toughness, low density, and good corrosion resistance. This article discusses the applications of titanium and titanium alloys in gas turbine engine components, aerospace pressure vessels, optic-system support structures, prosthetic devices, and applications requiring corrosion resistance and high strength. It explains the effects of alloying elements in titanium alloys as they play an important role in controlling the microstructure and properties and describes the secondary phases and martensitic transformations formed in titanium alloy systems. Information on commercial and semicommercial grades and alloys of titanium is tabulated. The article also discusses the different grades of titanium alloys such as alpha, near-alpha alloys, alpha-beta alloys, beta alloys, and advanced titanium alloys (titanium-matrix composites and titanium aluminides).

This article reviews the corrosion behavior of intermetallics for the modeling of the corrosion processes and for devising a strategy to create corrosion protective systems through alloy and coating design. Thermodynamic principles in the context of high-temperature corrosion and information on oxidation; sulfidation; hot corrosion of NiAl-, FeAl-, and TiAl-based intermetallics; and silicides are included. The article explores the thermodynamic consideration, ordering influencing kinetics, stress-cracking corrosion, and hydrogen embrittlement of aqueous corrosion. It also explains the practical issues dealing with the corrosion problems.

This article focuses on the modeling and simulation of cavitation phenomena. It summarizes the experimental observations of cavitation and reviews the modeling of cavity nucleation and growth. The article discusses the modeling of the cavity growth based on mesoscale and microscale under uniaxial versus multiaxial tensile-stress conditions. Mesoscale models incorporate the influence of local microstructure and texture on cavitation. The article outlines the descriptions of cavity coalescence and shrinkage. It also describes the simulation of the tension test to predict tensile ductility and to construct failure-mechanism maps.

High temperature corrosion may occur in numerous environments and is affected by factors such as temperature, alloy or protective coating composition, time, and gas composition. This article explains a number of potential degradation processes, namely, oxidation, carburization and metal dusting, sulfidation, hot corrosion, chloridation, hydrogen interactions, molten metals, molten salts, and aging reactions including sensitization, stress-corrosion cracking, and corrosion fatigue. It concludes with a discussion on various protective coatings, such as aluminide coatings, overlay coatings, thermal barrier coatings, and ceramic coatings.