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).

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 discusses the application of thermodynamic in the form of phase diagrams for visually representing the state of a material and for understanding the solidification of alloys. It presents the derivation of the relationship between the Gibbs energy functions and phase diagrams, which forms the basis for the calculation of phase diagrams (CALPHAD) method. The article also discusses the calculation of phase diagrams and solidification by using the Scheil-Gulliver equation.

This article reviews some of the trends in superalloy development as they relate to U.S. strategic materials availability and the aerospace industry. It discusses the supply sources and availability of strategic materials and summarizes the status of U.S. resources and reserves. The article presents a list of several superalloys that have been used in gas turbine engines or that are emerging as replacements because of the promise of increased operating temperatures and higher efficiencies for the aircraft of the future. It concentrates on the objectives, results, and methodology of the NASA Conservation of Strategic Aerospace Materials (COSAM) program.

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 focuses on the metallography and microstructures of wrought and cast aluminum and aluminum alloys. It describes the role of major alloying elements and their effect on phase formation and the morphologies of constituents formed by liquid-solid and/or solid-state transformations. The article also describes specimen preparation procedures and examines the microstructure of several alloy samples.

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.

Superalloys are predominantly nickel-base alloys that are strengthened by solid-solution elements including molybdenum, tungsten, cobalt, and by precipitation of a Ni 3 (Al, Ti) type compound designated as gamma prime and/or a metastable Ni 3 Nb precipitate designated as gamma double prime. This article provides a discussion on the conventional processing, compositions, characteristics, mechanical properties, and applications of powder metallurgy (PM) superalloys. The conventional processing of PM superalloys involves production of spherical prealloyed powder, screening to a suitable maximum particle size, blending the powder to homogenize powder size distribution, loading powder into containers, vacuum outgassing and sealing the containers, and consolidating the powder to full density. PM superalloys include Rene 95, IN-100, LC Astroloy, Udimet 720, N18, ME16, RR1000, Rene 88DT, PA101, MERL 76, AF2-1DA, Inconel 706, AF115, and KM4. The article reviews specialized PM superalloy processes and technical issues in the usage of PM superalloys.

This article describes the liquidus plots, isothermal plots, and isopleth plots used for a hypothetical ternary phase space diagram. It discusses the single-phase boundary (SPB) line and zero-phase fraction (ZPF) line for carbon-chromium-iron isopleth. The article illustrates the Gibbs triangle for plotting ternary composition and discusses the ternary three-phase phase diagrams by using tie triangles. It describes the peritectic system with three-phase equilibrium and ternary four-phase equilibrium. The article presents representative binary iron phase diagrams, showing ferrite stabilization (iron-chromium) and austenite stabilization (iron-nickel).

The term isomorphous refers to metals that are completely miscible in each other in both the liquid and solid states. This article discusses the construction of simple phase diagrams by using the appropriate points obtained from time-temperature cooling curves. It describes the two methods to determine a phase diagram with equilibrated alloys: the static method and the dynamic method. The article illustrates the construction of phase boundaries according to the Gibbs' phase rule and describes the calculation methods that allow the prediction of the phases present, the chemical compositions of the phases present, and the amounts of phases present. Phase diagrams provide useful information for understanding alloy solidification. The article provides two simple models that can describe the limiting cases of solidification behavior.

This article provides a thorough review of the physical metallurgy of aluminum alloys and its role in determining the properties and from a design and manufacturing perspective. And its role in include the effects of composition, mechanical working, and/or heat treatment on structure and properties. This article focuses on the effects of alloying and the metallurgical factors on phase constituents, structure, and properties of aluminum alloys. Effects from different combinations of alloying elements are described in terms of relevant alloy phase diagrams. The article addresses the underlying alloying and structural aspects that affect the properties and possible processing routes of aluminum alloys. It provides information on the heat treatment effects on the physical properties of aluminum alloys and the microstructural effects on the fatigue and fracture of aluminum alloys. The important alloying elements and impurities are listed alphabetically as a concise review of major effects.

This article discusses the various methods for evaluating the quench sensitivity of aluminum alloys, namely, time-temperature-property diagrams, the quench factor analysis, the Jominy end-quench method, and continuous-cooling precipitation diagrams. It briefly describes the procedures, applications, advantages, and limitations of these methods.

This article discusses three distinct mechanisms of bonding for solid-state (forge) welding processes, namely, contaminant displacement/interatomic bonding, dissociation of retained oxides, and decomposition of the interfacial structure. It explains the processes that can be characterized as having two stages: heating and forging. The article also includes a table that illustrates weld strengths as a function of annealing temperature for a range of materials.

Magnesium-matrix composites (MgMCs) are very promising as structural materials because of their low density, high specific strength, and excellent castability. This article provides information on the characteristics, mechanical properties, and applications of magnesium alloys and composites. It discusses the microstructures used for the most common magnesium alloys used in metal-matrix composites, namely, magnesium-aluminum, magnesium-rare earth and magnesium-lithium alloys. The article focuses on the most common methods of heat treatment, including solution heat treatment, precipitation strengthening or aging, and annealing, applied to these alloys. Finally, it describes the microstructural aspects and precipitate-matrix relationships of MgMCs as well as the heat treatment methods for MgMCs.

This article describes the effects of alloying and heat treatment on the metastable transition precipitates that occur in age hardenable aluminum alloys. Early precipitation stages are less well understood than later ones. This article details the aging sequence and characteristics of precipitates that occur in the natural aging and artificial aging of Al-Mg-Si-(Cu) alloys, Al-Mg-Cu alloys, microalloyed Al-Mg-Cu-(Ag, Si) alloys, aluminum-lithium-base alloys, and Al-Zn-Mg-(Cu) alloys. Crystal structure, composition, dimensions, and aging conditions of precipitates are detailed. Effects of reversion, duplex annealing, and retrogression and re-aging are included.

Weldability is a function of three major factors: base material quality, welding process, and design. This article focuses on base-metal weldability of aluminum alloys in terms of mechanical property degradation in both the weld region and heat-affected zone, weld porosity, and susceptibility to solidification cracking and liquation cracking. It provides an overview on welding processes, including gas metal arc welding, gas tungsten arc welding, resistance spot and seam welding, laser beam welding, and various solid-state welding processes. A review on joint design is also included, mainly in the general factors associated with service weldability (fitness). The article also provides a discussion on the selection and weldability of non-heat-treatable aluminum alloys, heat treatable aluminum alloys, aluminum-lithium alloys, and aluminum metal-matrix composites.

This article describes the classification of ferritic stainless steels. It reviews the metallurgical characteristics of various ferritic grades as well as the factors that influence their weldability. The article provides a discussion on various arc welding processes. These processes include gas-tungsten arc welding (GTAW), gas-metal arc welding (GMAW), flux-cored arc welding (FCAW), shielded metal arc welding (SMAW), and plasma arc welding (PAW). The selection criteria for welding consumables are discussed. The article also explains the welding procedures associated with the ferritic stainless steels. It concludes with information on weld properties.

This article is a compilation of definitions of terms related to metallography and microstructures.