Texture Analysis

One of the first areas where EBSD was used was in texture analysis.  As you have learnt, many materials are polycrystalline.  However, the grains in polycrystalline materials are not usually oriented randomly.     The grains often cluster close to certain orientations.  The way in which the orientations cluster is called the texture.   Textures form because of the ways in which grains form from molten material and from later processing steps.

In a single crystal, physical properties are different depending on the direction in the crystal in which  they are measured.  So the physical properties of polycrystalline material are dependent on the distribution of crystal orientations present.

Formability of sheet materials is strongly dependent on the material texture and the processing steps in reaching the final material are monitored carefully to ensure the texture is achieved.   For example, the texture in aluminium sheets used for beverage cans is carefully controlled - if it were not the tops of the cans would be uneven or the surface not smooth.  Many electrical and magnetic material properties also depend on crystal orientation.  For example, the cores of electrical transformers are textured in a way to reduce the energy losses in the transformer.

Because EBSD measures crystal orientation the data it provides can also be used to analyse the sample texture.  In this way, EBSD is complementary to the standard method of measuring texture using X-ray diffraction.  However, EBSD goes further because it can relate the texture (or textures) present to the microstructure of the material.   In addition, textures which vary from place to place in a sample can be studied easily.  The way in  which textures develop can be studied at the level of the microstructure with EBSD.

Left: Sample with random grain orientations (non-textured).  Right: Sample with non random grain orientations (textured)

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