A simple procedure for the assessment of plastic strain in electron back-scatter diffraction patterns

摘要

Electron backscatter diffraction (EBSD) is a scanning electron microscopy (SEM) technique for obtaining crystallographic information from very small surface regions of bulk specimen, typically - 0.5 urn diameter by 30nm depth. The technique is known mainly for its application to microtextnre i.e. spatially specific individual orientation measurement. A less commonly exploited application is for the measurement of plastic strain, .based on the fact that such strain is accompanied by diffuseness in the EBSD pattern. This diffuseness, or blurring, is a result of electrons being scattered away from the Bragg condition by defects within the crystal such as dislocations, which cause local bending of the lattice planes. Whereas it is easy to recognise qualitatively a diffise EBSD, such as one arising from a cold-worked region of microstructure compared to that from a recrystallised grain, it turns out to be far from a trivial exercise to quantify this information. Currently two methods are used to quantify the diffuseness of EBSD patterns.