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 behaviour. The original implementation of this science was limited by the resolution of the reflected light microscope used to study specimens. This limitation has been overcome by the development of transmission and scanning electron microscopies (TEM and SEM). The analysis of X-rays generated by the interaction of electron beams with atoms at or near the surface, with wavelength or energy-dispersive spectroscopy (WDS, EDS) with SEM, electron microprobe analysis (EMPA) or TEM has added quantitative determination of local compositions, e.g., of intermediate phases, to the deductions based upon observations. Introduction of metrological and stereological methods, and the development of computer-aided image analysers, permits measurement of micro structural features. Crystallographic data can be obtained using classic X-ray diffraction methods using a diffractometer, or diffraction analysis can be performed with the TEM using selected area or convergent-beam electron diffraction (SAD and CBD) techniques, and more recently with the SEM with the orientation-imaging (EBSD) procedure. There is a wide variety of very sophisticated electron or ion devices that can be utilised to characterise surfaces and interfaces, but these devices are generally restricted in availability due to their high cost.

Conventional light-optical techniques are still the most widely used and are capable of providing the information needed to solve most problems. Examination by light optical microscopy (LOM) should always be performed before use of electron...