Search Results for neutron diffraction

Neutrons are a principal tool for the study of lattice vibrational spectra in materials. This article provides a detailed account of fission and spallation methods of neutron production that are capable of producing sufficient intensity to be useful in neutron scattering research. It describes the instrumentation required for, and advancements made in, neutron powder diffraction. The article further explains the texture and residual stress (macrostresses and microstresses) problems that are analyzed using the neutron powder diffraction method. It also outlines the single-crystal neutron diffraction technique, and provides examples of the applications of neutron diffraction.

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.

This article discusses the central aspect of anisotropy modeling, namely, texture measurement and analysis. It provides an overview of the methods available for characterizing crystallographic preferred orientation, or texture, in polycrystalline materials. These methods include pole figure measurement and electron backscatter diffraction (EBSD). The article describes the process considerations for pole figure measurement, including X-ray diffraction, neutron diffraction, stereographic projection, equal area projection, graphing pole figures, typical textures, and orientation distribution. It also deals with the limitations and challenges associated with the EBSD, and applications of the diffraction.

This article briefly discusses popular techniques for metals characterization. It begins with a description of the most common techniques for determining chemical composition of metals, namely X-ray fluorescence, optical emission spectroscopy, inductively coupled plasma optical emission spectroscopy, high-temperature combustion, and inert gas fusion. This is followed by a section on techniques for determining the atomic structure of crystals, namely X-ray diffraction, neutron diffraction, and electron diffraction. Types of electron microscopies most commonly used for microstructural analysis of metals, such as scanning electron microscopy, electron probe microanalysis, and transmission electron microscopy, are then reviewed. The article contains tables listing analytical methods used for characterization of metals and alloys and surface analysis techniques. It ends by discussing the objective of metallography.

This article discusses the need of and the strain basis for residual stress measurements and describes the nature of residual stress fields. A generic destructive stress relief procedure is described along with the issues generally involved in each procedural step. The article presents the stress reconstruction equations to be used for computational reconstruction of the stress fields from the measured strains for the destructive methods. It provides information on the sectioning, material removal, strain measurement, and chemical methods of residual stress measurement. The article reviews the semidestructive methods of residual stress measurement: blind hole drilling and ring coring, spot annealing, and X-ray diffraction techniques. Nondestructive methods such as neutron diffraction, ultrasonic velocity, and magnetic Barkhausen noise techniques, are also discussed.

This article discusses the standard test methods that can be applied to many types of welds: tension, bending, impact, and toughness testing. It provides information on four qualification stages, namely, the weld material qualification, base material qualification, the weld procedure qualification, and the weld service assessment. The article describes two general types of measurements for residual stress in welds: locally destructive techniques and nondestructive techniques. Locally destructive techniques include hole drilling, chip machining, and block sectioning. Nondestructive techniques include X-ray diffraction, neutron diffraction, Barkhausen noise analysis, and ultrasonic propagation analysis. The article concludes with an overview of weldability testing.

The diffraction pattern of any material contains structural and chemical property information that can be extracted using radial distribution function analysis. This article provides an introduction to the technique and presents several examples highlighting various ways in which it can be used. It begins with a discussion on the principles of diffraction and scattering and the effectiveness of x-ray, neutron, and electron energy sources for different types of measurements. It provides information on data collection and reduction and explains how to create atomic distribution plots from intensity and scattering angle data. The article also presents application parameters for defining short distances and background intensity and describes a procedure for generating pair distribution functions.