Metallography/Materialography

Metallography or materialography is used to qualitatively and above all quantitatively characterise the structure of a material using predominantly optical methods. In combination with mechanical, physical and chemical test methods, a comprehensive characterisation of a material can be carried out.

Application

Metallography or materialography, which also includes non-metallic materials, is used to qualitatively and above all quantitatively describe the microstructure of a material (metal, slag, ceramic, etc.), i.e. the spatial arrangement, size, shape, distribution and volume fraction of crystallites and all other phases as well as their structural identification. The structure of the microstructure determines the properties of a material, which is why the determination of the chemical composition alone is often not sufficient for a comprehensive characterisation. By analysing the microstructure, changes caused by manufacturing, use and ageing can be traced and made visible. Materialographic working methods can be used to comprehensively analyse inhomogeneities, coatings (gilding, tinning, painting, etc.), manufacturing technology or corrosion, as well as combined object groups (e.g. crucibles with adhering slag). The specimens can be used for further solid state analysis methods (XRF, LA-ICP-MS, µ-XRD, etc.) or hardness testing to determine the chemical composition, structure and mechanical properties.

Basics

Interaction of electromagnetic waves or corpuscular beams with solids and their surface properties.

Limits

The methods are generally not non-destructive and it is often not possible to take representative samples of cultural artefacts due to the required sample quality. Archaeological objects are sometimes too heavily degraded for a sample to be taken or analysed.

Sample composition

Solids, undisturbed solid and representative samples of at least 1 mm3 to cm3 (depending on material and research question). For all analyses, completely flat, scratch-free and dust-free specimens must be prepared. For this purpose, the samples must be embedded in suitable materials such as synthetic resins and the surface prepared. In individual cases, the samples can also be removed from the embedding material.