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.

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 is a compilation of ternary alloy phase diagrams for which copper (Cu) is the first-named element in the ternary system. The other elements are Fe, Mn, Ni, Pb, S, Sb, Si, Sn, Ti and Zn. The diagrams are presented with element compositions in weight percent. The article includes 42 phase diagrams (liquidus projection, solidus projection, isopleths, isothermal section and vertical section).

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.

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).

This article is a compilation of ternary alloy phase diagrams for which germanium (Ge) is the first-named element in the ternary system. The diagrams are presented with element compositions in weight percent. The article includes phase diagram of Ge-Sb-Te liquidus projection.

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 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 silver (Ag) 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: Ag-Au-Cu liquidus projection; Ag-Au-Cu isothermal section at 850 °C; Ag-Au-Cu isothermal section at 950 °C; Ag-Au-Cu isothermal section at 775 °C; Ag-Au-Cu isothermal section at 300 °C; Ag-Cd-Cu isothermal section at 600 °C; Ag-Cd-Cu liquidus projection; Ag-Cd-Cu isothermal section at 500 °C; Ag-Cd-Cu isothermal section at 300 °C; Ag-Cd-Zn isothermal section at 600 °C; Ag-Cd-Zn liquidus projection; Ag-Cd-Zn isothermal section at 400 °C; Ag-Cd-Zn isothermal section at 200 °C; Ag-Cu-Zn isothermal section at 600 °C; Ag-Cu-Zn liquidus projection; and Ag-Cu-Zn isothermal section at 350 °C.

This article is a compilation of ternary alloy phase diagrams for which lead (Pb) is the first-named element in the ternary system. The diagrams are presented with element compositions in weight percent. The article includes 7 phase diagrams: Pb-Sb-Sn liquidus projection; Pb-Sb-Sn isothermal section at 240 °C; Pb-Sb-Sn isothermal section at 189 °C; Pb-Sb-Sn (Pb) liquidus projection; Pb-Sn-Zn liquidus projection; and Pb-Sn-Zn isothermal section at 532 °C.

This article presents ternary alloy phase diagrams to be used primarily by engineers to solve industrial problems. The diagrams presented are for stable equilibrium conditions, with the exception of metastable conditions for some diagrams involving carbon and iron. In some ternary diagrams involving carbon and iron, the symbol M is used to represent both iron and the other metallic element when the two metals substitute for each other in a carbide phase.

This article is a compilation of ternary alloy phase diagrams for which cadmium (Cd) is the first-named element in the ternary system. The diagrams are presented with element compositions in weight percent. The article includes 4 phase diagrams: Cd-Sb-Sn isothermal section at 212 °C; Cd-Sb-Sn liquidus projection; Cd-Sb-Sn isothermal section at 175 °C; and Cd-Sb-Sn isothermal section at 20 °C.

This article is a compilation of ternary alloy phase diagrams for which cobalt (Co) is the first-named element in the ternary system. The other elements are Cr, Cu, Fe, Mo, Ni, Ti, V, and W. The diagrams are presented with element compositions in weight percent. The article includes 36 phase diagrams (liquidus projection, solidus projection and isothermal section).

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 is a compilation of ternary alloy phase diagrams for which gold (Au) is the first-named element in the ternary system. The diagrams are presented with element compositions in weight percent. The article includes five phase diagrams: Au-Cu-Ni boundaries of solid-state miscibility gap; Au-Cu-Ni liquidus projection; Au-Cu-Ni miscibility gap at 400 degrees centigrade; Au-Cu-Ni miscibility gap at 700 degrees centigrade; and Au-Sn-Te liquidus projection.

This article is a compilation of ternary alloy phase diagrams for which boron (B) 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: B-C-Fe liquidus projection; and B-Fe-Nd liquidus projection.

This article is a compilation of ternary alloy phase diagrams for which carbon (C) is the first-named element in the ternary system. The other elements are Co, Cr, Cu, Fe, Mn, Mo, N, Ni, S, Si, Ti, V, and W. The diagrams are presented with element compositions in weight percent. The article includes 136 phase diagrams (solidus projection, liquidus projection, isothermal section and vertical section).

This article introduces basic physical metallurgy concepts that may be useful for understanding and interpreting variations in metallographic features and how processing affects microstructure. It presents some basic concepts in structure-property relationships. The article describes the use of equilibrium binary phase diagrams as a tool in the interpretation of microstructures. It reviews an account of the two types of solid-state phase transformations: isothermal and athermal. The article discusses isothermal transformation and continuous cooling transformation diagrams which are useful in determining the conditions for proper heat treatment (solid-state transformation) of metals and alloys. The influence of the mechanisms of phase nucleation and growth on the morphology, size, and distribution of grains and second phases is also described.

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.