Search Results for niobium ternary system

This article is a compilation of ternary alloy phase diagrams for which niobium (Nb) is the first-named element in the ternary system. The diagrams are presented with element compositions in weight percent. The article includes 2 phase diagrams: Nb-Ti-W isothermal section at 600 °C; and Nb-Ti-W isothermal section at 1000 °C.

This article is a compilation of ternary alloy phase diagrams for which molybdenum (Mo) is the first-named element in the ternary system. The diagrams are presented with element compositions in weight percent. The article includes 8 phase diagrams: Mo-Nb-Ti isothermal section at 600 °C; Mo-Nb-Ti isothermal section at 1100 °C; Mo-Ni-Ti isothermal section at 1200 °C; Mo-Ni-Ti isothermal section at 900 °C; Mo-Ni-W isothermal section at 700 °C; Mo-Ni-W isothermal section at 1000 °C; Mo-Ti-W isothermal section at 2227 °C; and Mo-Ti-W isothermal section at 1000 °C.

This article is a compilation of ternary alloy phase diagrams for which iron (Fe) is the first-named element in the ternary system. The diagrams are presented with element compositions in weight percent. The article includes 16 phase diagrams: Fe-Mn-Ni liquidus projection; Fe-Mn-Ni isothermal section at 750 °C; Fe-Mn-Ni isothermal section at 850 °C; Fe-Mn-Ni isothermal section at 650 °C; Fe-Mn-Ni isothermal section at 550 °C; Fe-Mo-Nb isothermal section at 1050 °C; Fe-Mo-Nb isothermal section at 1150 °C; Fe-Mo-Nb isothermal section at 900 °C; Fe-Mo-Ni liquidus projection; Fe-Mo-Ni isothermal section at 1100 °C; Fe-Mo-Ni isothermal section at 1200 °C; Fe-Ni-W liquidus and solidus projections; Fe-Ni-W isothermal section at 1500 °C; Fe-Ni-W isothermal section at 1455 °C; Fe-Ni-W isothermal section at 1465 °C; and Fe-Ni-W isothermal section at 1400 °C.

Superconductors are materials that exhibit a complete disappearance of electrical resistivity on lowering the temperature below the critical temperature. A superconducting material must exhibit perfect diamagnetism, that is, the complete exclusion of an applied magnetic field from the bulk of the superconductor. Superconducting materials that have received the most attention are niobium-titanium superconductors (the most widely used superconductor), A15 compounds (in which class the important ordered intermetallic Nb3Sn lies), ternary molybdenum chalcogenides (Chevrel phases), and high-temperature ceramic superconductors. This article provides an overview of basic principles of superconductors and the different classes of superconducting materials and their general characteristics.

This article is a compilation of ternary alloy phase diagrams for which chromium (Cr) is the first-named element in the ternary system. The other elements are Fe, Mn, Mo, N, Nb, Ni, Ti, V and W. The diagrams are presented with element compositions in weight percent. The article includes 55 phase diagrams (liquidus projection, solidus projection, isothermal section and vertical section).

This article is a compilation of ternary alloy phase diagrams for which aluminum (Al) is the first-named element in the ternary system. The other elements are C, Co, Cr, Cu, Fe, Ga, Li, Mg, Mn, Mo, Nb, Ni, Sb, Si, Ti, U, V and Zn. The diagrams are presented with element compositions in weight percent. The article includes 136 phase diagrams (liquidus projection, solidus projection, isothermal section, vertical section, and solvus projection).

This article reviews the phase diagrams, alloy with third element additions, layer growth, critical current density, and matrix materials of A15 superconductors. It describes the production methods of tape conductors (chloride deposition, and surface diffusion) and multifilamentary wires (rod process, modified jelly roll process, niobium tube process, in-situ process, powder metallurgy process, and jelly roll method). The article focuses on reaction heat treatment, which is required at the end of wire processing to convert the ductile components to the desired, but brittle, superconductor. Finally, it discusses the applications of A15 superconductors in commercial magnets, power generation, power transmission, high-energy physics, and fusion.

The application of phase diagrams is instrumental in solid-state transformations for the processing and heat treatment of alloys. A unary phase diagram plots the phase changes of one element as a function of temperature and pressure. This article discusses the unary system that can exist as a solid, liquid, and/or gas, depending on the specific combination of temperature and pressure. It describes the accomplishment of conversion between weight percentage and atomic percentage in a binary system by the use of formulas. The article analyzes the effects of alloying on melting/solidification and on solid-state transformations. It explains the construction of phase diagrams by the Gibbs phase rule and the Lever rule. The article also reviews the various types of alloy systems that involve solid-state transformations. It concludes with information on the sources of phase diagram.

This article discusses four types of defects in materials that have been fusion welded and that have been the focus of much attention because of the magnitude of their impact on product quality. These include hot cracks, heat-affected zone (HAZ) microfissures, cold cracks, and lamellar tearing. These defects, all of which manifest themselves as cracks, are characteristic of phenomena that occur at certain temperature intervals specific to a given alloy. The article presents selected alloy 625 compositions used in weldability study.

Tantalum is one of the most versatile corrosion-resistant metals known. The outstanding corrosion resistance and inertness of tantalum are attributed to a very thin, impervious, protective oxide film that forms on exposure of the metal to slightly anodic or oxidizing conditions. This article provides a discussion on the mechanism of corrosion resistance and on the behavior of tantalum in different corrosive environments, namely, acids; salts; organic compounds; reagents, foods, and pharmaceuticals; body fluids and tissues; and gases. It contains several tables that summarize the effects of acids, salts, and miscellaneous corrosive reagents on tantalum and applications for tantalum equipment in chemical, pharmaceutical, and other industries. Finally, the article presents a discussion on hydrogen embrittlement, the galvanic effects, and cathodic protection of tantalum and describes the corrosion resistance of different types of tantalum-base alloys.

The residual porosity in sintered refractory metal ingots is usually eliminated by different densification processes, such as thermomechanical processes. This article focuses on thermomechanical processing of tungsten, molybdenum, and tantalum. It provides an overview of liquid-phase sintering of tungsten heavy alloys and describes the infiltration of tungsten and molybdenum for attaining full density. The article concludes by providing information on hot isostatic pressing of refractory metal alloys to full density.

This article focuses on the industrial applications of phase diagrams. It presents examples to illustrate how a multicomponent phase diagram calculation can be readily useful for industrial applications. The article demonstrates how the integration of a phase diagram calculation with kinetic and microstructural evolution models greatly enhances the power of the CALPHAD approach in materials design and processing development. It also discusses the limitations of the CALPHAD approach.

Alloy phase diagrams are useful for the development, fabrication, design and control of heat treatment procedures that will produce the required mechanical, physical, and chemical properties of new alloys. They are also useful in solving problems that arise in their performance in commercial applications, thus improving product predictability. This article describes different equilibrium phase diagrams (unary, binary, and ternary) and microstructures, description terms, and general principles of reading alloy phase diagrams. Further, the article discusses plotting schemes; areas in a phase diagram; and the position and shapes of the points, lines, surfaces, and intersections, which are controlled by thermodynamic principles and properties of all phases that comprise the system. It also illustrates the application of the stated principles with suitable phase diagrams.

This article reviews the fundamental solidification concepts for understanding microstructural evolution in fusion welds. The common concepts, namely, nucleation, competitive grain growth, constitutional supercooling, solute redistribution, and rapid solidification, depend on the solidification parameters during welding, are discussed. The article discusses important solidification parameters, including temperature gradient, solid/liquid interface growth rate, and cooling rate.

This article provides information on the liquid lithium systems that are exposed to liquid metal. It discusses the forms in which liquid-metal corrosion is manifested. The influence of several key factors on the corrosion of metals and alloys by liquid-metal systems or liquid-vapor metal coolants is described. Some information on safety precautions for handling liquid metals, operating circulating systems, dealing with fire and spillage, and cleaning contaminated components, are also provided.

This article describes various procedures used in the metallographic preparation of niobium, tantalum, molybdenum, and tungsten alloys. It provides information on sectioning, grinding, mounting, polishing, and electrolytic etching as well as alternate procedures that have been used on refractory metals. The article presents and analyzes several micrographs, provides etchant formulas for various materials, and discusses the unique characteristics of rhenium and its alloys.

This article illustrates the three techniques for producing glassy metals, namely, liquid phase quenching, atomic or molecular deposition, and external action technique. Devitrification of an amorphous alloy can proceed by several routes, including primary crystallization, eutectoid crystallization, and polymorphous crystallization. The article demonstrates a free-energy versus composition diagram that summarizes many of the devitrification routes. It provides a historical review of the corrosion behavior of fully amorphous and partially devitrified metallic glasses. The article describes the general corrosion behavior and localized corrosion behavior of transition metal-metal binary alloys, transition metal-metalloid alloys, and amorphous simple metal-transition metal-rare earth metal alloys. It concludes with a discussion on the environmentally induced fracture of glassy alloys, including hydrogen embrittlement and stress-corrosion cracking.

Low-expansion alloys are materials with dimensions that do not change appreciably with temperature. Alloys included in this category are various binary iron-nickel alloys and several ternary alloys of iron combined with nickel-chromium, nickel-cobalt, or cobalt-chromium alloying. Low-expansion alloys are used in various applications such as rods and tapes for geodetic surveying, moving parts that require control of expansion (such as pistons for some internal-combustion engines), bimetal strip, components for electronic devices etc. This article discusses the properties, composition, and applications of iron-nickel low-expansion alloys (Invar), as well as other special alloys, including iron-nickel-chromium alloys, iron-nickel-cobalt alloys, iron-cobalt-chromium alloys, and high-strength, controlled-expansion alloys. It covers the factors affecting coefficient of thermal expansion of iron-nickel alloys, including heat treatment and cold drawing. Magnetic, physical, thermal, electrical and mechanical properties of iron-nickel alloys are also covered.