Ultramicroscopy103(2005)41–58 Orientationeffectsonindexingofelectronbackscatter diffractionpatterns MatthewM.Nowell à ,StuartI.Wright EDAX-TSL, 392 E 12300 S, Suite H, Draper, UT 84020, USA Abstract Automated Electron Backscatter Diffraction (EBSD) has become a well-accepted technique for characterizing the crystallographicorientationaspectsofpolycrystallinemicrostructures.Attheadventofthistechnique,itwasobserved that patterns obtained from grains in certain crystallographic orientations were more difficult for the automated indexingalgorithmstoaccuratelyidentifythanpatternsfromotherorientations.Theoriginofthisproblemisoften similaritiesbetweentheEBSDpatternofthecorrectorientationandpatternsfromotherorientationsorphases.While practicalsolutionshavebeenfoundandimplemented,theidentificationoftheseproblemorientationsgenerallyoccurs onlyafterrunninganautomatedscan,asproblemorientationsareoftenreadilyapparentintheresultingorientation maps.However,suchanapproachonlyfindsthoseproblemorientationsthatarepresentinthescanarea.Itwouldbe advantageoustoidentifyallregionsoforientationspacethatmaypresentproblemsforautomatedindexingpriorto initiating an automated scan, and to minimize this space through the optimization of acquisition and indexing parameters.Thisworkpresentsnewmethodsforidentifyingregionsinorientationspacewherethereliabilityofthe automated indexing is suspect prior to performing a scan. This methodology is used to characterize the impact of variousparametersontheindexingalgorithm. r 2004ElsevierB.V.Allrightsreserved. PACS: 87.64.bx;68.37.d;61.14.x Keywords: Electronbackscatterdiffraction;EBSD;Orientation;Indexing;Confidenceindex 1. Introduction TheautomatedanalysisofElectronBackscatter Diffraction (EBSD) patterns for orientation ima- ging has become an established technique for crystallographic microstructural characterization in materials and earth sciences, and has been successfully applied to a wide range of materials and crystal structures [1]. However, it was observed early in the development of this techni- quethatforcertaincrystallographicorientationsit isdifficulttodetermineauniqueindexingsolution ARTICLE IN PRESS www.elsevier.com/locate/ultramic 0304-3991/$-seefrontmatter r 2004ElsevierB.V.Allrightsreserved. doi:10.1016/j.ultramic.2004.11.012 à Corresponding author. Tel.: +18014952750; fax: +18014952758. E-mail address: matt.nowell@ametek.com(M.M.Nowell).