Microstructural Characterization Using 3-D Orientation Data Collected by an Automated FIB-EBSD System

Abstract

Inthis work, a new technique utilizing an automated approach ofcombining a Focused Ion Beam (FIB) and Electron Back-Scatter Diffraction(EBSD) system was implemented for the collection of 3-D orientationdata that can be used to more accurately model grainand sub-grain particle structures. The process is currently capable ofsectioning a sample with inter-slice thicknesses as low as 100nanometers and capturing an orientation map of each slice. Automationof this technique allowed for rapid data collection with theability to update settings in real time. The orientation dataobtained by the EBSD scans consists of each grid point'sposition, three Euler angles and phase. Reconstruction of the 3-Dorientation data involves combining or "stacking" the 2-D slices obtainedby the FIB-EBSD process. The orientation data of each sliceis combined into one data file containing orientation information foreach point on the 3-D grid, which can have spacingas little as 100 nanometers in all three directions. Aprogram developed in this work, Micro-Mesher, uses the reconstructed orientationinformation to define microstructural features such as grains and secondphase particles. Micro-Mesher constructs grain boundaries with line and planesegments using an error per unit length approach to approximatethe complex grain boundaries. Important microstructural statistics that are usedto define and characterize the 3-D microstructure are also calculatedby Micro-Mesher. Such important parameters include: grain size, no. ofneighboring grains, orientations and misorientations, second phase particles size andinter particle spacing as well as others. The 3-D statisticalinformation gained from this process improves the ability to accuratelycharacterize the microstructure. ©2004 American Institute of Physics