THE BASIC CONCEPTS OF TEXTURE INVESTIGATION IN POLYCRYSTALLINE MATERIALS

Polycrystalline materials consist of grains which may have different sizes, shapes and arrangements to be observed under the microscope as well as different crystal orientations observed by diffraction methods. The orientation parameters of the crystallites are subsumed under the term texture. The main textural quantities are the orientation distribution function ODF of the crystallites and the misorientation distribution function MODF of grain- and phase boundaries. Textures are being formed in materials by all kinds of anisotropic solid state processes and they have influence on all kinds of anisotropic material properties. Textures can be measured grain-by-grain or using polycrystal diffraction methods. The appropriate radiations are X-rays, electrons and neutrons. Finally, some examples are given concerning martensitic transformation in FeNi-alloys, shape memory alloys, cross-rolling of Armco-iron, biaxially stretched polyethylene, and HT(c) superconductors.