IMPROVED PHASE DIFFERENTIATION AND ORIENTATION IMAGING VIA COMBINED EBSD AND EDS

The automated analysis of Electron Backscatter Diffraction (EBSD) patterns in a Scanning Electron Microscope (SEM) to determine crystal orientation for phase identification and orientation imaging is well established for multiphase materials. However for many of these materials it is difficult to reliably and consistently differentiate the constituent phases using EBSD alone. For geological materials, these difficulties can occur due to the complexity of the crystal structures and the similar crystal symmetries that are often present, as well as the subtle changes of crystal structure that can occur due to solid-solution ranges for many naturally occurring mineral series. Traditionally during orientation imaging data collection, a list of suspected candidate phases are specified, and each acquired EBSD pattern is automatically analyzed and the best-fit phase is selected from the candidate list. When the crystallography of the candidate phases are similar, it becomes difficult to determine the correct phase with EBSD. Using elemental information collected via Energy Dispersive Spectroscopy (EDS), it is often easy to distinguish the crystallographically similar minerals. By simultaneously collecting the EBSD and EDS information, it is then possible to selected the candidate phase for each pattern by elemental information, and then determine the crystallographic orientation. The process improves both the speed and the accuracy of the phase differentiation and orientation imaging results. Examples of this procedure and the limitations involved with be presented and discussed.