This article discusses the fundamental aspects of phase-field microstructure modeling. It describes the evolution of microstructure modeling, including nucleation, growth, and coarsening. The article reviews two approaches used in the modeling nucleation of microstructure: the Langevin force approach and explicit nucleation algorithm. Calculation of activation energy and critical nucleus configuration is discussed. The article presents the deterministic phase-field kinetic equations for modeling growth and coarsening of microstructure. It also describes the material-specific model inputs, chemical free energy and kinetic coefficients, for phase-field microstructure modeling. The article provides four examples that illustrate some aspects of phase-field modeling.

This article describes the changes in structure and properties that occur when cold worked metals and alloys are annealed. Recovery, recrystallization, and grain growth are the three stages of structural change that occur when cold-worked metal is annealed. The driving force and extent of structural or property changes may depend on alloy structure and the degree of prior work.

This article assesses the evolution of martensite modeling in the changing materials engineering environment. It describes the physics of displacive transformations using Ginzburg-Landau theory, microstructure representation, dynamics and simulations, density functional theory, and shuffle transitions. The article reviews the application of the Ginzburg-Landau approach to rigorous solutions for issues in the structure of a martensitic nucleus based on the martensitic nucleation theory. The three basic behavior modes of martensitic growth, such as elastic, elastic/plastic, and fully plastic are discussed. The article also reviews the overall kinetics of martensitic transformations.

This article describes the results obtained by Volmer, Weber, Farkas, Becker, and Doring, which constitute the classical nucleation theory. These results are the predictions of the precipitate size distribution, steady-state nucleation rate, and incubation time. The article reviews a nucleating system as a homogeneous phase using the classical nucleation theory, along with heterophase fluctuations that led to the formation of precipitates. It discusses the gas cluster dynamics using the kinetic approach to describe nucleation. The article presents key parameters, such as cluster condensation and evaporation rates, to describe the time evolution of the system. The predictions and extensions of the classical nucleation theory are discussed. The article also provides the limitations of classical nucleation theories in cluster dynamics.

Recovery, recrystallization, and grain growth are the stages that a cold worked metal undergoes when it is annealed. This article describes the changes in the structure and properties that occur on annealing a cold-worked metal. It summarizes the experimental recrystallization studies by Burke and Turnbull with six laws of recrystallization. Applications of these laws of recrystallization are discussed in detail with examples. The article reviews the classification of grain growth according to the growth behavior of grains, namely, normal or continuous grain growth and abnormal or discontinuous grain growth. The latter has also been termed exaggerated grain growth, coarsening, or secondary recrystallization.

The solidification of hypoeutectic cast iron starts with the nucleation and growth of austenite dendrites, while that of hypereutectic iron starts with the crystallization of primary graphite in the stable system or cementite in the metastable system. This article begins with a discussion on the nucleation and growth of austenite dendrites. It describes the nucleation of lamellar graphite, spheroidal graphite, and austenite-iron carbide eutectic. The article reviews three main graphite morphologies crystallizing from the iron melts during solidification: lamellar (LG), compacted or vermicular (CG), and spheroidal. It discusses the metastable solidification of austenite-iron carbide eutectic and concludes with information on gray-to-white structural transition of cast iron.

This article discusses selected highlights of thermodynamic relationships during solidification and nucleation kinetics behavior in connection with the basis of nucleation treatments, such as grain refinement and inoculation, to provide a summary of nucleation phenomena during casting. The article describes nucleation phenomenon such as homogeneous nucleation and heterogeneous nucleation. It examines various grain refinement models, such as the carbide-boride model, the free growth model, and the constitutional undercooling model. The article concludes with information on the thermal analysis techniques for assessing grain-refining characteristics during master alloy processing.

This article is a compilation of definitions of terms related to materials characterization techniques.

Radionuclide methods for wear measurement are used to measure wear continuously throughout a tribological experiment at a resolution of nanometers or micrograms per hour. This article presents an overview of radionuclide methods for wear measurement. It discusses complementary wear measurement methods to introduce the advantages of using radioactive isotopes (RI) for wear or corrosion measurements in comparison to other methods. The article provides information on radiation safety regulations and approaches to minimize external radiation exposure. It describes neutron activation, thin layer or surface layer activation, and ultrathin layer or recoil activation that are used to create radioactive isotopes in the samples to be tested. The article reviews the two common types of wear measurement setup configurations: the direct method and the indirect method. It concludes with a discussion on the practical application of wear measurement using radioactive isotopes.

This article summarizes the general features of microstructure evolution during the thermomechanical processing (TMP) of nickel-base superalloys and the challenges posed by the modeling of such phenomena. It describes the fundamentals and implementations of various modeling methodologies. These include JMAK (Avrami) models, topological models, and mesoscale physics-based models.

This article presents an overview of fatigue crack nucleation from the point of view of the material microstructure and its evolution during cycling. It describes the sites of microcrack nucleation at the free surfaces. The article discusses the relation of dislocation structures and surface relief and reviews the mechanisms of crack nucleation. The damage of material due to crack nucleation, the extent (in terms of the number of cycles) of the nucleation stage, and the factors influencing crack nucleation are discussed.

Recovery, recrystallization, and grain growth are microstructural changes that occur during annealing after cold plastic deformation and/or during hot working of metals. This article reviews the structure of the deformed state and describes the changes in the properties and microstructures of a cold-worked metal during recovery stage. It discusses the recrystallization that occurs by the nucleation and growth of grains. The article also reviews the growth behavior of the grains, explaining that the grain growth can be classified into two types: normal or continuous grain growth and abnormal or discontinuous grain growth. It also examines the key mechanisms that control microstructure evolution during hot working and subsequent heat treatment. These include dynamic recovery, dynamic recrystallization, metadynamic recrystallization, static recovery, static recrystallization, and grain growth.

Metallic glasses can be prepared by solidification of liquid alloys at cooling rates sufficient to suppress the nucleation and growth of competing crystalline phases. This article presents a historical survey of the study of metallic glasses and other amorphous metals and alloys. This includes a discussion of synthesis and processing methods, structure and morphology, and a description of the electronic, magnetic, thermodynamic, chemical, and mechanical properties of metallic glasses. In addition, the article describes the development of metallic glasses as materials for technical applications.

This article provides a brief introduction to neutron diffraction as well as its state-of-the-art capabilities. The discussion covers the general principles of the neutron, neutron-scattering theory, generation of neutrons, types of incident radiation, and purposes of single-crystal neutron diffraction, powder diffraction, and pair distribution function analysis. The relationship between detector space and reciprocal space are presented. Various factors involved in sample preparation, calibration, and techniques used for analyzing diffraction data are described. The article also presents application examples and possible future developments in neutron diffraction.

Inductively coupled plasma atomic emission spectroscopy (ICP-AES) is an analytical technique for elemental determinations in the concentration range of major to trace based on the principles of atomic spectroscopy. This article provides a description of the basic atomic theory, and explains the analytical procedures and various interference effects of ICP, namely, spectral, vaporization-atomization, and ionization. It provides a detailed discussion on the principal components of an analytical ICP system, namely, the sample introduction system; ICP torch and argon gas supplies; radio-frequency generator and associated electronics; spectrometers, such as polychromators and monochromators; detection electronics and interface; and the system computer with appropriate hardware and software. The article also describes the uses of direct-current plasma, and provides examples of the applications of ICP-AES.

The human internal environment plays a vital role in the friction and wear of implants and prosthetic devices. This article describes the tribological/wear behavior of implants. It discusses the classification of active tribological pairs, namely, amphiarthosis joints and diarthosis joints. The article details the classification of total knee replacement, depending on the type of mechanical stability, including nonconstrained knee replacement, semiconstrained knee replacement, and constrained knee replacement. It also discusses the classifications of passive tribological pairs, namely, total disc replacement in the spine, dental implants, and temporomandibular joint. It describes the various testing methods for characterizing the implant materials used in hip, knee, spine, and dental applications. The article also describes the typical standards used for testing wear behavior of tribological pairs, namely, hip-wear simulation standards, knee-wear simulation standards, and spinal disc-wear simulation standards.

Cast iron exhibits a considerable amount of eutectic in the solid state. This article discusses the structure of liquid iron-carbon alloys to understand the mechanism of the solidification of cast iron. It illustrates the nucleation of the austenite-flake graphite eutectic, austenite-spheroidal graphite eutectic, and austenite-iron carbide eutectic. The article provides a discussion on primary austenite and primary graphite. It also describes the growth of eutectic in cast iron in terms of isothermal solidification, directional solidification, and multidirectional solidification.