《EBSD数据分析》PPT课件

AnalysisofEBSDData(L17),27-750,Fall2009Texture,MicrostructurethedesignationofRD,TDandNDisonlycorrectforEuleranglesinreferencetotheplottedmaps/images,notthephysicalspecimen,TSLversusHKLReferenceFrames,+,Z(x),xspatial,yspatial,RD=100sample=xEuler,TD=010sample=yEuler,TSL,HKL,+,Z(x),xspatial,yspatial,RD=100sample=xEuler,TD=010sample=yEuler,Thetwospatialframesarethesame,exactlyasnotedbyChangsooKimandHerbMillerpreviously.Thefiguresshowimages(asopposedtophysicalspecimen).TheEuleranglereferencesframesdifferbyarotationof+90(add90tothefirstEulerangle)goingfromtheTSLtotheHKLframes(intermsofanaxistransformation,orpassiverotation).Viceversa,topassfromtheHKLtotheTSLframe,oneneedsarotationof-90(subtract90fromthefirstEulerangle).Thepositionofthe“sample”axesiscritical.Thenames“RD”and“TD”donotnecessarilycorrespondtothephysical“rollingdirection”and“transversedirection”becausethesedependonhowthesamplewasmountedinthemicroscope.,TestofEulerAngleReferenceFrames,TSL,AsimpletestoftheframesusedfortheEuleranglesistohavethesoftwaresplotpolefiguresforasingleorientationwithsmallpositivevaluesofthe3angles.Thisrevealsthepositionofthecrystalx-axisviathesenseofrotationimposedbythesecondEulerangle,F.Clearly,onehastoadd90to1topassfromHKLcoordinatestoTSLcoordinates.NotethattheCMUTSLisusingthex/1120convention(“Xconvention”),whereastheMetzChannel/HKLsoftwareisusingthey/1120convention(“Yconvention”).,Eulerangles:17.2,14.3,0.57,Hexagonalcrystalsymmetry(nosamplesymmetry),36,TheAxisAlignmentIssue,TheissuewithhexagonalmaterialsisthealignmentoftheCartesiancoordinatesystemusedforcalculationswiththecrystalcoordinatesystem(theBravaislattice).Inoneconvention(e.g.popLA,TSL),thex-axis,i.e.1,0,0,isalignedwiththecrystala1axis,i.e.the2,-1,-1,0direction.Inthiscase,they-axisisalignedwiththe0,1,-1,0direction.Intheotherconvention,(e.g.HKL,Univ.Metzsoftware),thex-axis,i.e.1,0,0,isalignedwiththecrystal1,0,-1,0direction.Inthiscase,they-axisisalignedwiththe-1,2,-1,0direction.Seenextpagefordiagrams.Thisisimportantbecausetextureanalysiscanleadtoanambiguityastothealignmentof2,-1,-1,0versus1,0,-1,0,withapparent30shiftsinthedata.Caution:itappearsthattheaxisalignmentisachoicethatmustbemadewheninstallingTSLsoftwaresodeterminationofwhichconventionisinusemustbemadeonacase-by-casebasis.Itisfixedtothey-conventionintheHKLsoftware.Themaincluethatsomethingiswronginaconversionisthateitherthe2110pictureisdrawnasiftheobserverwasthecamera.Notethatthemapsareturnedby180withrespecttothispicture.-originalEuleranglesaregiveninframe_1(alsocalledCS1)ThectfformatisdesignedtoexportEulerangleintoframe_0(CS0),whichiscorrect,providedthatthespecimenorientationiscorrectlydefined.,CS1=rawdataformat,CS0ismodifiedbytheusertoalignaxeshowevertheyplease.TheCTFformatalwaysexportsinCS0arrangement.,40,top,bottom,CS1,firstacquiredpixel(Xspatial=1,Yspatial=1)=topleftpixeloftheresultingmap,Xpix,Ypix,Xpix,Ypix,X1,Y1,Z1,CS1asshowninthevirtualchamber,HKLsoftwarekeepingCS0(sampleframe)alignedwithCS1(microscopeframe),relyingonwhatthevirtualchamberisshowing:,butthisalignmentisnotconsistentwiththeaxesofthePFplotsorwithpreviousexperiencewithdatasetsfromtheHKLsoftware,Tracesof10-10planes,beta-transformedTi(fromNathalieGey,LETAMnowLEM3),EBSDmap,Xspatial,Yspatial,Xpix,Ypix=spatialframeX0,Y0,Z0=eulerangleframe,supposedtobealignedwithX1,Y1,Z1(scopeframe),(Z0pointingout),NotethatarotationofthePFaxesby180aroundZtorecovertheframenumbered3onthePFplots,wouldalsobeconsistentwiththetracebeingperpendicularto,Eulerframe,Spatialframe,ThereisadiscrepancyintheHKLsoftwarebetweenhowtheframeCS1(andCS0)isrepresentedinthevirtualchamberandhowthePFaxesareplacedThedifferenceisarotationby180aroundtheZdirection(framenumbered2versusframe3)Itis