Electron Backscatter Diffraction (EBSD) has proven to be a useful tool for characterizing the crystallographic orientation aspects of microstructures at length scales ranging from tens of nanometers to millimeters in the scanning electron microscope (SEM). With the advent of high-speed digital cameras for EBSD use, it has become practical to use the EBSD detector as an imaging device similar to a backscatter (or forward-scatter) detector. Using the EBSD detector in this manner enables images exhibiting topographic, atomic density and orientation contrast to be obtained at rates similar to slow scanning in the conventional SEM manner. The high-speed acquisition is achieved through extreme binning of the camera-enough to result in a 5 × 5 pixel pattern. At such high binning, the captured patterns are not suitable for indexing. However, no indexing is required for using the detector as an imaging device. Rather, a 5 × 5 array of images is formed by essentially using each pixel in the 5 × 5 pixel pattern as an individual scattered electron detector. The images can also be formed at traditional EBSD scanning rates by recording the image data during a scan or can also be formed through post-processing of patterns recorded at each point in the scan. Such images lend themselves to correlative analysis of image data with the usual orientation data provided by and with chemical data obtained simultaneously via X-Ray Energy Dispersive Spectroscopy (XEDS).

Nucleation and propagation of tensile twins in magnesium alloy AZ31 are investigated for a large number of twins at an early stage of their development. High-resolution electron backscatter diffraction (HREBSD) techniques are employed to give additional insights. Correlations with grain orientation, boundary misorientation and active slip systems are observed in the region of twins that arise at grain boundaries. Two types of twin are identified: 1) slipassisted twins that nucleate at grain boundaries with no apparent influence from nearby twins, and 2) twin-assisted twins that result from twins propagating across a grain boundary. Twinning occurs in "hard" grains that cannot accommodate necessary contraction via -type slip. Slip assisted twins nucleate at high-angle boundaries. Twin-assisted twinning occurs at low-angle boundaries. The distributions of grain boundary misorientation associated with each type of twin

To explore the driving forces behind deformation twinning in Mg AZ31, a machine learning framework is utilized to mine data obtained from electron backscatter diffraction (EBSD) scans in order to extract correlations in physical characteristics that cause twinning. The results are intended to inform physics-based models of twin nucleation and growth. A decision tree learning environment is selected to capture the relationships between microstructure and twin formation; this type of model effectively highlights the more influential characteristics of the local microstructure. Trees are assembled to analyze both twin nucleation in a given grain, and twin propagation across grain boundaries. Each model reveals a unique combination of crystallographic attributes that affect twinning in the Mg. Twin nucleation is found to be mostly controlled by a combination of grain size, basal Schmid factor, and bulk dislocation density while twin propagation is affected most by grain boundary length, basal Schmid factor, angle from grain boundary plane to the RD plane, and grain boundary misorientation. The machine

Electron backscatter diffraction (EBSD) dislocation microscopy is an important, emerging field in metals characterization. Currently, calculation of geometrically necessary dislocation (GND) density is problematic because it has been shown to depend on the step size of the EBSD scan used to investigate the sample. This paper models the change in calculated GND density as a function of step size statistically. The model provides selection criteria for EBSD step size as well as an estimate of the total dislocation content. Evaluation of a heterogeneously deformed tantalum specimen is used to asses the method.

A grain boundary sliding creep mechanism, accommodated by "mantle" dislocation activities, is shown to allow for large strain (ε > 0.08) during the creep of a ZrB 2-20% SiC composite at 1800°C. We characterized the local grain deformation behavior using high resolution electron backscatter diffraction (HREBSD) microscopy and an indentation deformation mapping (IDM) technique. Deformation gradients near grain boundaries ("mantle") produced average geometrically necessary dislocation (GND) densities of 3x10 11-4x10 12 cm-2 , about one order of magnitude above that of the grain interiors ("core"). A deviation from single crystal grain core deformation defines the mantle where excess GND's accommodate the grain deformation gradient. Evidence supporting grain boundary sliding as the primary contribution to the creep strain appears in our earlier publication, but we show here the role of dislocations in the deformation of the grain mantle as the rate-controlling accommodation step.