Metallography is the imaging of topographical or microstructural features on prepared surfaces of materials. The properties and performance of materials are controlled by the structures studied by metallography.

In this technique, planar surfaces are prepared to obtain a polished finish. Chemical or other etching methods are often used to delineate macrostructure and microstructure features,which provide information on phase distribution, grain size, solidification structure, and thermo-mechanical processing history.

Metallography is also used for characterizing the macroscopic and microscopic configuration at planar sections of welds, brazes, and fabricated components. In failure analysis, morphology or corrosion of cracks can be characteristic of failure mode. The prepared samples are examined by the unaided eye, light microscopy, and/or electron microscopy.

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Macrostructure evaluation-Deep chemical etching is typically utilized to characterize large-scale material inhomogeneities in composition, structure, density, etc. This method is useful for evaluation of welds, brazes, castings, forgings, and organic-matrix composites for configuration, defects, and structure.

Microstructure evaluation-Characteristic features provide information regarding composition, phase distribution, mechanical and physical properties, thermomechanical processing and defects.

Quantitative metallography-Observed features can be analyzed to obtain measurements of characteristics including grain size, phase volume fractions, and linear dimensions. Measurements are made manually or by computerized semi-automated methods on digitally-acquired images.

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• Metal alloy heat treatment verification
• Coating thickness measurements
• Weld or braze joint evaluation
• Case hardening depth determination
• Corrosion resistance evaluation
• Failure analysis
• Microscopic defects in semiconductor devices
• Microscopic configuration

SEM Model: JEOL JSM-5800 LV SEM

Light Microscope Model: Reichert MeF3 Metallograph

Most samples are sectioned and encapsulated in a metallographic mount to facilitate preparation. The mount sizes range from about 1 in. (25 mm) to 3 in. (75 mm) in diameter. Sections up to about 8 in. (200 mm) across can be prepared in the laboratory without mounting. For large samples or samples that cannot be cut, localized areas are prepared in situ and evaluated using a field microscope or replicas of the prepared surface.

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