Search Results for titanium-aluminum-base alloys

This article describes the development of heat-resistant titanium-base alloys and their classification into several microstructure categories based on their strengthening mechanisms. It explains the phase transformation in titanium-aluminum-base alloys and two peritectic reactions that take place in the titanium-aluminum system. The article also describes two approaches for controlling the orientation of the high-temperature alpha phase to achieve the required lamellar orientation by directional solidification in order to improve the strength and ductility of titanium-aluminum alloys. One approach is by seeding the alpha phase in the alloys, and the other is without seeding, by controlling the solidification path of alloys through appropriate alloying. The article discusses the grain refinement technique used to improve the ductility of cast titanium-aluminum alloys to a level of above 1" at room temperature and reasonable room temperature ductility in the as-cast condition. Finally, it provides information on the microstructures produced through various near-net shape manufacturing processes.

Corrosion resistance can usually be maintained in the welded condition by balancing alloy compositions, shielding molten and hot metal surfaces, and choosing the proper welding parameters. This article describes some of the metallurgical factors that affect corrosion of weldments. It also reviews the considerations for selected nonferrous alloy systems such as aluminum, titanium, tantalum, and nickel.

Coextrusion welding (CEW) is a solid-state process that produces a weld by heating two or more workpieces to the welding temperature and forcing them through an extrusion die. This article describes cold and hot CEW for common metals such as low-carbon steel, aluminum, aluminum alloys, copper, and copper alloys. Additional applicable materials include nickel, nickel-base alloys, zirconium, titanium, tantalum, and niobium.

This article discusses the effects of brazing temperature and thermal treatment on structure and mechanical behavior of different classes of titanium base metals such as commercially pure (CP) titanium, alpha or near-alpha alloys, alpha-beta alloys, and beta alloys. The classification, properties, and potential heat treatment of titanium base alloys are presented in tables. The article provides information on brazed joints of titanium with carbon steels, as well as ceramics and graphite. It discusses the risks involved in titanium brazing, including erosion of base metal, brittle intermetallics, and low ductility. The article reviews induction and torch brazing, infrared brazing, diffusion brazing, and brazing by heating with ion bombardment. It concludes by describing the design criteria and limitations of brazing.

Nonferrous metals and alloys are widely used to resist corrosion. This article describes the corrosion behavior of the most widely used nonferrous metals, such as aluminum, copper, nickel, and titanium. It also provides information on several specialty nonferrous products that cannot easily be categorized by elemental base.

This article focuses on the physical metallurgy and weldability of four families of titanium-base alloys, namely, near-alpha alloy, alpha-beta alloy, near-beta, or metastable-beta alloy, and titanium based intermetallics that include alpha-2, gamma, and orthorhombic systems.

Metallic matrices are essential constituents for the fabrication of metal-matrix composites (MMCs). This article describes three different classes of aluminum alloys, namely, commercial aluminum alloys, low-density and high-modulus alloys, and high temperature alloys. It presents typical tensile properties and fracture toughness of the selected heat treatable aluminum alloys in a table. Titanium alloys are very attractive for MMC applications, due to their higher strength and temperature capability compared to aluminum alloys. The article tabulates the effect of heat treatment on room-temperature properties and tensile properties of Ti-25Al-17Nb alloy sheet.

The term shape memory alloys (SMAs) refers to the group of metallic materials that demonstrate the ability to return to some previously defined shape or size when subjected to the appropriate thermal procedure. Materials that exhibit shape memory only upon heating are referred to as having a one-way shape memory. Some materials also undergo a change in shape upon recooling. These materials have a two-way shape memory. This article discusses the general characteristics of SMAs by using typical transformation versus temperature curve. It describes the processing, applications and properties (mechanical and physical) of commercial SMA alloys, namely nickel-titanium alloys and copper-base alloys.

This article describes the factors considered in the analysis of brazeability and solderability of engineering materials. These are the wetting and spreading behavior, joint mechanical properties, corrosion resistance, metallurgical considerations, and residual stress levels. It discusses the application of brazed and soldered joints in sophisticated mechanical assemblies, such as aerospace equipment, chemical reactors, electronic packaging, nuclear applications, and heat exchangers. The article also provides a detailed discussion on the joining process characteristics of different types of engineering materials considered in the selection of a brazing process. The engineering materials include low-carbon steels, low-alloy steels, and tool steels; cast irons; aluminum alloys; copper and copper alloys; nickel-base alloys; heat-resistant alloys; titanium and titanium alloys; refractory metals; cobalt-base alloys; and ceramic materials.

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.

This article provides a discussion on filler metal selection, brazing procedures, and brazing equipment for brazing refractory metals. These include molybdenum, tungsten, niobium, and tantalum, and reactive metals. Commercially pure and alpha titanium alloys, alpha-beta alloys, zirconium alloys, and beryllium alloys are some reactive metals discussed in the article.

Titanium has been recognized as an element with good mechanical and physical properties, alloying characteristics, and corrosion resistance. Providing an outline of general characteristics and types of titanium alloys, this article discusses the contemporary technology of titanium along with its market developments. It also discusses the application of titanium and titanium alloys in corrosive environments and in aerospace and automotive industries. The article describes the developments in titanium processing and materials technologies, which include the development of sponge production and melting processes, oxide dispersion-strengthened alloys by powder metallurgy techniques, titanium-base intermetallic compounds, and titanium-matrix composites.

The warm and hot working of metals provide the ability to shape important materials into component shapes that are useful in a variety of applications requiring strength, toughness, and ductility. This article focuses on a variety of metals that can be hot or warm worked, and describes the characteristics and processing considerations of each metal. It discusses forging because it is a versatile metalworking process and performed at cold, warm, and hot working temperatures. The article also presents the applications of steels, stainless steels, aluminum alloys, titanium alloys, superalloys, and copper alloys.

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).

This article reviews specific processing characteristics and forging-related properties of commonly forged families of metals and alloys, including carbon and alloy steels, stainless steels, heat-resistant alloys (iron, cobalt, and nickel base alloys), aluminum alloys, copper and copper alloys, magnesium alloys, and titanium alloys. It provides forging process variables such as stock preparation, heating and cooling of forgings, die lubrication, trimming, and cleaning of these metals and alloys. The article explains the effect of temperature, deformation rate, and die temperature on forgeability and describes the forging methods of these metals and alloys.

This article describes two methods based on rolling of sheet. The first is roll welding, where two or more sheets or plates are stacked together and then passed through rolls until sufficient deformation has occurred to produce solid-state welds. The other is laser roll welding, which is a hybrid process based on a thin-melting interface for a lap joint of dissimilar-metal sheets using a roller and one-sided laser heating. The article discusses the types, advantages, and applications of roll welding and laser roll welding. It also provides a detailed discussion on the laser roll welding of dissimilar metals.

This article contains a table that lists the thermal conductivity of selected metals and alloys near room temperature. These include aluminum and aluminum alloys; copper and copper alloys; iron and iron alloys; lead and lead alloys; magnesium and magnesium alloys; nickel and nickel alloys; tin and tin alloys; titanium and titanium alloys; zinc and zinc alloys; and pure metals.

This article focuses primarily on the various steps involved in the brazing of heat-resistant alloys (nickel- and cobalt-base alloys). The major steps include the selection of brazing filler metals, surface cleaning and preparation, brazing processes and their corresponding atmospheres, and fixturing. The article also provides an overview of the brazing of blow-alloy steels and tool steels and oxide dispersion-strengthened alloys.

This article discusses the mechanics of chip formation and reviews the analytical modeling of the chip formation process by high-speed machining within the framework of continuum mechanics. It examines the relationship between the various high-speed machining parameters. The article describes the cutting tool systems for aluminum alloys, steel, superalloys, and titanium alloys and provides an overview of the alternative cutting tool geometries for increasing tool life. It highlights the factors considered by companies planning to employ high-speed machining systems and concludes with information on the applications of high-speed machining.