BOOK_CONTENT
From Smithells Light Metals Handbook

Overview

Metallography can be defined as the study of the structure of materials and alloys by the examination of specially prepared surfaces. Its original scope was limited by the resolution and depth of field in focus by the imaging of light reflected from the metallic surface. These limitations have been overcome by both transmission and scanning electron microscopy (TEM, STEM and SEM). The analysis of X-rays generated by the interaction of electron beams with atoms at or near the surface, by wavelength or energy dispersive detectors (WDX, EDX), has added quantitative determination of local composition, e.g. of intermetallic compounds, to the deductions from the well-developed etching techniques. Surface features can also be studied by collecting and analysing electrons diffracted from the surface. A diffraction pattern of the surface can be used to determine its crystallographic structure (low-energy electron diffraction or LEED). These electrons can also be imaged as in a conventional electron microscope (Low-energy electron microscopy or LEEM). This technique is especially useful for studying dynamic surface phenomena such as those occurring in catalysis. X-rays photoelectron microscopy (XPS or ESCA) now enables the metallographer to analyse the atoms in the outermost surface layer to a depth of a few atoms (0.3 5.0 nm) and provides information about the chemical environment of the atom. Auger spectroscopy uses a low-energy electron beam instead of X-rays to excite atoms, and analysis of the Auger electrons produced provides similar information about the atoms from which the Auger electron is ejected.

Nevertheless, the conventional optical techniques...

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Topics of Interest

7.1 Aluminium Alloys 7.1.1 Annealing For softening aluminium alloys that have been hardened by cold work: Alloys 1080A, 1050, 1200, 5251, 5154A, 5454, 5083 -360 C for 20 min. Alloys 3103, 3105 -...

Overview Metallography is the branch of science dealing with the study of the constitution and structure of metals and alloys, its control through processing, and its influence on properties and...

4.1 Introduction and Cross References X-rays are very short wavelength electromagnetic waves. Their range encompasses the interatomic distances in crystalline materials, typically 0.5 to 2.5 , which...

X-ray methods involve the excitation of an atom by the removal of an electron from an inner energy level, usually from the innermost K level or from one of the three L levels. Atoms can be excited...

E. Bauer Spin-polarized low energy electron microscopy is one of several methods for the study of the magnetic microstructure of surfaces and thin films on surfaces. It is a non-scanning, full-field...