Barrett-2017-Effect of grain boun

rmElKa,b,aDpartmntofMchanicalEnginring,MississippiStbCntrforAdancdVhicularSystm,MississippiStacDpartmntofMchanicalandMchatronicsEnginrdUSArmyRsarchLaboratory,AbrdnProingGrouarticlinfoArticlhistory:Rcid17August2016txturformation;simulationsandthoryshowthatthtwinboundaryhasahighlymobilb2=2odominatthfinalAllrightsrsrdmissions,andimprodrangoflctricalhicls[15]ThtchnicalchallngformagnsiumalloysinmanyindustrialapplicationsisthformabilityatroomtmpraturAstmpraturischnicalchallngnduringdynamicchallngscanbncofalloyinglmntsinmagnsiumalloysandththrmomchanicalprocssingpathsonthfinalcrystallographictxturofmagnsiumcanhlptodsignbttralloysintrmsofmchanicalproprtisand,ultimatly,matrialprformancMuchofthpoorformabilityofmagnsiumalloyscanbtracdtothhxagonalclospackdcrystalstructurofmagnsiumalloys,whichladstoanumbrofpossibldformationmchanismsCorrspondingauthorDpartmntofMchanicalEnginring,MississippiStatUnirsity,MS39762,UnitdStatsContntslistsaailabActaMatlsActaMatrialia128(2017)270283Emailaddrss:lkadiri@mmsstatdu(HElKadiri)alloysholdthpromistotrmndouslyrducthmassofhicls,allowingforbttrfulfficincy,lowrgrnhousgasorcomhasmotiatdlarginstmntsinrsarchanddlopmntofwroughtmagnsiumalloysUndrstandingthinfludisconnctionwithawiddislocationcor,prsumablycausingthaffctdgrainsttxtur©2017ActaMatrialiaIncPublishdbyElsirLtd1IntroductionThhighspcificstrngthandlowdnsityofmagnsium(Mg)incrasd,toincrasthformability,anothrtprsntsitslfthchallngoftxturformatiorcrystallizationThpotntialimpactifthsmobilitisrlatitoothrboundaris,makingthmprimcandidatsforaccommodatingsubgrainrotationInparticular,anwxprimntallyobsrdf1340gtwinboundaryisassociatdwiththRcidinrisdform21Dcmbr2016Accptd28January2017Aailablonlin3Fbruary2017Kywords:DynamicrcrystallizationGrainboundarisDislocationsTwinningMagnsiumhttp:dxdoiorg101016jactamat20170106313596454©2017ActaMatrialiaIncPublishdbyEatUnirsity,MS39762,UnitdStatstUnirsity,MS39762,UnitdStatsing,UnirsityofWatrloo,Watrloo,N2L3G1,Canadand,MD21005,USAabstractBasalslipanddynamicrcoryofdislocationshabnlongassumdasthmainmchanismsaccountingforthsharptxturingofmagnsiumalloysupondynamicrcrystallizationathightmpraturBasalslipallowsthbasalplantomitigatstrssbyrorintingth⟨c⟩axisnormaltothloadingdirction,whildynamicrcoryallowsdislocationstorarrangintosubgrainswhilmaintainingthbasalplanparallltothmainloadingaxisThsphnomna,thoughprtainingtounqustionabllawsofplasticityandthrmodynamics,donotfullyxplainthprfrrdslctionofcrystalorintationduringnuclationandgrowthofdynamicallyrcrystallizdgrainsForxampl,duringxtrusion,thbasalplanrorintsitslfinonoftwodirctions,whrithrth⟨1120⟩axisorth⟨1010⟩axisisparallltothxtrusiondirctionAlso,onlyafw(grainboundary)misorintationrlationshipsarstablishdbtwnthrcrystallizdandthparntgrainsInthispapr,lctronbackscattrddiffraction(EBSD)charactrizationonpartiallyrcrystallizdmicrostructurs,molculardynamicsimulations,andintrfacialdfctthoryarusdtouncorthmchanismsladingtothphnomnaoftxturformationduringdynamicrcrystallizationSimulationsshowthatgrainboundarynrgyandmobilitymrgasthkygorningffctsinthxprimntallyobsrdprfrrdorintationslctionduringnuclationandgrowthDutothlowcrystalsymmtryinhrnttothhxagonalclospackdstructurofmagnsium,crtaingrainboundarispossssbothlowintrfacialnrgisandhighChristophrDBarrtt,AMarkATschoppd,Haithamadiria,bidinImandousta,b,AndrwLOppdala,b,KaanInalc,FulllngtharticlEffctofgrainboundarisontxturforcrystallizationofmagnsiumalloysjournalhompag:wwwlsirLtdAllrightsrsrdationduringdynamiclatScincDirctrialiaircomlocatactamatAdministratorHighlightAdministratorHighlightAdministratorHighlightAdministratorHighlightAdministratorHighlightAdministratorHighlightatrdutoitsnoncubicsymmtryAtthsinglcrystalll,haingasclospackdandasistslipmodbasal⟨a⟩,ð0001Þ⟨1120⟩;Mgcannotsustainasystrainalongth⟨c⟩axisThnxthardrslipmodisknownasprismatic⟨a⟩,f1010g⟨1120⟩,butisstillunabltoaccommodatdformationinadirctionoutsidthbasalplanThfirstaailablslipmodwithaBurgrsctorhaingacaxiscomponntwasobsrdtobthpyramidal⟨cþa⟩�⟨1123⟩,lyingarguablyithronf1122gorf1011glatticplans[69]Howr,thisslipmodisatlastfitimsashardtotriggrasthclospackdslipdirctionons,thrbynablinginnormalquasistatictstconditions,f1012g⟨1011⟩twins,whichcanaccommodat⟨c⟩axistnsionorxtnsion[1013]Thf1011g⟨1012⟩twinningmodhasalsobnobsrdtoaccommodat⟨c⟩axiscomprssionorcontractioninhighrstrainrgimsandatfractur[10,11,14,15]Thishighpropnsityoftwinningandthlargdisparitisinstrngthofactidformationmodshabnlinkdwithstrongllsofanisotropyandasymmtry[16],aswllasamarkdrductioninthductilityofsinglcrystalsastmpraturdcrassandstrainratincrass[7,17,18]FormosttraditionalMgpolycrystals,thdgrofthslimitationsrmainslarglyunchangd,astypicalrollingandxtrusionoprationsladtorysharptxturs,typicallyinthformof⟨c⟩axisor⟨a⟩axisfibrs,rspctily[1923]ManynwmatrialsdsignstratgishasubsquntlymrgdtonginrbttrmchanicalbhaiorbydlopingbttralloysandprocssingschmsArguablythmostsuccssfulapproachsadocatmitigatingthtndncyofMgtodlopsharptxtursbymicroalloying(i,randomizingtxtur),ludingthanisotropicbhaior(akintosinglcrystals)instructuralapplicationsAdditionsofrararth(RE)lmnts[24],hapronmostfficintinthisrgard,asthyhanabldanoticabldropinthyildpointandanincrasinbothuniformandtotallongation,nindilutsolutions[2540]Howr,thductilityofcostffctiMgREalloyshanotytrachdthllthatmtsthprformancrquirmntsrlatdtonrgyabsorption,formability,andcorrosionHighprformancMgREalloyhabndlopdbyusingsignificantconcntrationsofREcomponnts(i>02wt%Cto>1wt%Y),butthhighcostandlimitdsupplyofRElmntsmakthsalloysprohibitiinmanyapplicationsFurthrmor,itisstillnotclarlyundrstoodxactlyhowREadditionsaffctthcrystallographictxturingofMgalloysAswithmanymatrialsdsignstratgis,undrstandingthoprablmchanismsatthappropriatlngthscalsisoftnthfirststptodsigningbttrmatrials;thnxtstpistoxploitthknowldgofthsmchanismstotailorthproprtisandprformancofnwmatrialsWhilthpriousparagraphfocusdonalloyingstratgis,anothrcriticalcomponntofdsigningbttrmagnsiumalloysistobttrundrstandthmchanismsaffctingtxturingatmodratlyhightmpraturs(i,dynamicrcrystallization)TraditionalMgalloysarthoughttorcrystallizuniformlyathightmpraturinamannrwhichdosnothadiscrniblydistinctgrainnuclationandgrowthstags,ispatiallyandtmporallycontinuousdynamicrcrystallization(CDRX)[4147]ThCDRXprocssinMgisproducdbyamchanismofdynamicpolygonizationinrotatdlatticrgionsclostograinboundaris(GBs)[48]Howr,thoriginofsharptxtursduringthisprocssisstillnotrywllundrstoodImportantly,unlikfaccntrdandbodycntrdcubicmatrials,dynamicrcrystallizationinwroughtMgrsultsmostlyinthsamtxtur[4955]Rcrystallizdcubicmatrialsmayhaastrongrtxtur,orawakronthanthdformationtxtur,andlikwisthtxturcomponntsmaybaltrdorrmainCDBarrtttalActaMsimilar[45,5658]Bycontrolofthprocssingariabls,manipulationofthtxturtosuccssfullyproducadsirablmicrostructurhasbnfarmorsuccssfulforcubicalloysthanforMgalloysandsimilarhxagonalclospackd(HCP)mtals[45,59,60]ThobjctiofthprsntstudyistounralthmchanismsrsponsiblfortxturformationinMgalloysduringCDRXAfundamntalundrstandingofthisrlationshipbtwnCRDXandtxturformationcanladtoapproachsforbttrdsigningalloysandthrmomchanicalprocsss,aswllasprhapsbttrundrstandinghowRElmntswaknprfrrdcrystallographictxturingduringCDRXInthiswork,whausdacombinationofcharactrizationbylctronbackscattrddiffraction(EBSD),molculardynamicssimulations,andintrfacialdfctthorytoundrstandtxturformationinanAM30alloythatundrwntdynamicrcrystallizationduringxtrusionRsultsofEBSDdataonahightmpraturxtrudd,partiallyrcrystallizd,aluminummangansmagnsium(AM30)alloyhlpdtomapthmisorintationrlationshipsbtwnthparntandrcrystallizdgrains,withthgoalofidntifyinganytndncisofprfrrdgrainorintationsorprfrrdgrain(twin)boundarisInparticular,EBSDrsultswranalyzdusingintrgranularmisorintationanalysis(IGMA)totrackthffctofdislocationtypsinthorintationslctionprocssofrcrystallizdmbryosThsxprimntalobsrationswrsubsquntlyanalyzdfurthriaMDsimulationsandintrfacialdfctthorytoshowthatparticulargrainboundariswrrsponsiblforthsharptxtursinMgThanalysisofthssimulationsclarifidthrolofgrainandtwinboundarisindynamicrcrystallization,whichholdthkyforundrstandingtxturformationinMgalloys2Exprimntalandsimulationmthodology21ExprimntalalloysThmatrialusdinthisstudywasAM30magnsiumalloywiththfollowingchmicalcomposition(wt%):254Al,04Mn,0018Zn,0003F,0008Si,0011Cu,0025C,0005Ni,MgbalancThmatrialusdinthisstudyisfromthsamsamplusdtoinstigatmchanismsbhindtwinslipandtwintwinintractionsintrmsofdislocationtransmutationsthatrsultinstrainhardningdutoprofustwinning[24]Sompriousrcrystallizationbhaiorwasinstigatdinthsammatrialwasalsoconductd[61,62]Thisalloywntthroughasquncofxtrusionprocsssina4200tonprssthatrducdthinitialdiamtrofthbilltfrom18indownto13inandthn9inatatmpraturof570�Candaspdof03ms�1Spcimnsanalyzdinthisworkwrxtractdfromth9inbilltbywirEDM(lctricaldischargmachining)ThsymmtryofthxtruddbilltisprsntdinFig1,whrthxtrusiondirction(ED)isparallltothcylindrmainaxis,thxtrusionradialdirction(ERD)isparallltoanyradiusofthbilltcrosssction,andthxtrusionnormal(EN)isprpndiculartobothEDandERDSamplswrxtractdfromapproximatlyatthmidradiusasshowninFig122EBSDanalyssMicrotxturanalysswrprformdusingaZissSupra40FESEMquippdwithaHikariEBSDcamraTSLOIMdataacquisitionandanalysissoftwarpackagwasusdfordataanalysisThEBSDanalysistchniquhasbnusdsuccssfullybymanyrsarchrsforrcrystallizationstudis[64]andrcrystallizationinmagnsium[65]ialia128(2017)270283271ThEBSDsamplswrmachindfromthxtruddbillt,andAdministratorHighlightdtaillswhr[67,68],wasusdtoidntifyGND(gomtricallyncssarydislocation)contntinrgionscloslynighboringrcrystallizdgrainsYamasakitalusdIGMAanalysistostudykinkbandsinaMgZnYalloy[69]ThisanalysistchniqunablsthmasurmntandidntificationofsmallmisorintationsbtwnadjacntrgionswithinagrainThprimaryintrstinthisstudyisthdislocationtypdfindbythrotationaxis,withlssimportancbingassigndtothCDBarrtttalActaMatrialia128(2017)270283272analyzdfromsctionsnormalandparallltothxtrusiondirction(ED),asillustratdinFig1Aftrtraditionalgrindingandpolishingprocdurs,thsamplswrlctropolishdwithStrursC1solutionat20Vfor20susingStrursLctropol5followdbysonicatingfor20minaftrprparationinabsolutthanoltormothartifactsfromthsurfacSamplswrthnscanndinarious400mm�300mmlargrgionswithastpsizof01mmforEBSDmappingThlattrsctionwasnormaltothERDThgrainboundarycharactrandtxturwasdtrmindforbothparntandrcrystallizdgrainsItisncssarytosparatthGBmisorintationanglsandtxtursintodistinctpartitionstoFig1Schmaticillustrationofthxuddbilltsymmtryshowingthxtrusiondirction(ED)andthxtrusionradialdirction(ERD)whosnormalsctionswrpolishdandanalyzdbylctronbackscattrddiffraction(EBSD)Thxtrusionnormal(EN)isnormaltobothEDandERD(RprintdwithprmissionfromMatal[63])dtrminthdiffrncsassociatdwiththDRXmchanismHr,thgrainorintationspradtchniquwasusdtoquantifythorintationspraddistributionwithinthtxtur,rflctingthxtntofdformationllwithinachgrainThgrainorintationsprad(GOS)inachgrainisdtrmindbycalculatingtharagmisorintation(angl)btwnallpointssampldwithinthgrainThisoprationisprformdbycomputingtharag(macroscopic)grainorintationandthnbycalculatingtharagdiationbtwnthmacroscopicgrainorintationandth(microscopic)crystalorintationsofachpointwithinthgrainThdynamicallyrcrystallizdgrainstypicallyhaanorintationspradlssthan1�2�,whilparntgrainshaanorintationspradgratrthan10�Thgomtricallyncssarydislocation(GND)contntwasalsodtrmindforthparntandrcrystallizdgrainsThIntragranularMisorintationAxis(IGMA)analysis[66],dscribdinTabl1ListofTayloraxscorrspondingtoslipsystmsobsrdinMgalloys;dnotsaTayloSlipModSlipTypBurgrsVctorf0001g<1120>Basal<a>a=3<1120>f0010g<1210>Prismatic<a>a=3<1120>f1011g<1210>Pyramidal<a>a=3<1120>f1011g<1123>PyramidalI<cþa>a=3<1123>f1122g<1123>PyramidalII<cþa>a=3<1123>actualamountofrotationbythdislocationHnc,onlythprsncofrsidualgomtricallyncssarydislocationsischaractrizdhrinThTayloraxis[6971]gisthaxisofplasticrotationdutothactiityofasinglslipsystmTabl1displaysthxpctdTayloraxsforthbasal⟨a⟩,prismatic⟨a⟩,pyramidal⟨a⟩,andpyramidal⟨cþa⟩slipsystmsxpctdtobactiinMgalloys[72]23MacrotxturmasurmntsForoptimumgrainstatistics,thtxturaragdorthwholsamplolumwasmasurdusingthHIPPOnutrontimofflightdiffractomtratLANSCE(LosAlamosNutronScincCEntr)Thsamplswrmountdonsamplholdrsandmasurdatrotationanglsof0�,45�,675�and90�aroundthsamplcylindraxisusinganautomatdsamplchangr[73]Nutronswrdtctdby3Hdtctortubsgroupdon30dtctorpanlsarrangdon3ringswithnominaldiffractionanglsof140�,90�and40�Th120acquirdhistogramswranalyzdwiththMAUDprogram[74],usingthEWIMVmthodThpolfigurdatawasxportdfromMAUDandimportdintoMTEX[75]forfurthrprocssingandisualizationThpol8[76]softwarwasalsousdtoprpartxturdatastsfornumricalsimulationsThrsultsofmacrotxturmasurmntonthxtruddAM30alloyisshowninFig2Thisisatypicalrodprismatictxturxpctdfromxtrusionprocssing24MolculardynamicsimulationsTwodimnsionalEBSDanalysisdosnotdfinallofthfidgrsoffrdomthatcharactrizthboundary,asonlythtracofthboundaryplancouldbidntifidHowr,bcausofthlowsymmtryofthhxagonalstructur,sralgrainboundariswithhighrGBnrgisandlowrcoincidntsitlattic(CSL)symmtrywrliminatd,focusinginstadonlowrnrgyandhighrCSLsymmtryGBsthathathsammisorintationandboundaryplantracThsGBswrconstructdusingatomisticbasdtchniquspriouslydscribdinRfs[7881]ThGBconfigurationswrrlaxdusingacombinationoflowtmpraturquilibrationandconjugatgradintminimizationinLAMMPS[82]Liu'sEAMpotntial[83]wasusdforpurmagnsiumsimulationsThsimulationcllusdbothpriodicityofthHCPlatticwith3DpriodicboundaryconditionstosimulatthGBstructurandnrgyFrsurfacsnormaltothGBwrlocatdatadistancofraxisalidonlyforanidalcaratio(thothralusdonotdpndonthisratio)SlipSystmsTaylorAxsVariants3<1100>33<0001>16<1012>612<25;41;16;9>66<1100>3AdministratorHighlightAdministratorHighlightAdministratorHighlightAdministratorHighlightAdministratorHighlightAdministratorHighlightFig2Macrotxturrprsntdby½0001�and⟨1010⟩polfigursandmasurdusingnutrondiffractionona6mm�6mmlargcylindricalsampl(RprintdwithprmissionfromOppdaltal[77])(a)(b)(c)(d)Fig3TxturanalyssonahightmpraturxtruddAM30magnsiumalloyshowing(A)atypicalinrspolfigurmap,(B)grainorintationsprad(GOS)obtaindbyanalyzingfourlargEBSDscanssimilartothonshownonthlfthandsid,inrspolfigurmapsofthxtrusionradialdirctionofth(C)parntgrainsand(D)rcrystallizdgrainsThsmapsarxtractdfromthfullIPFmapin(A)byidntifyingrgionswithahighGOSasunrcrystallizdandrgionswithalowGOSasrcrystallizdCDBarrtttalActaMatrialia128(2017)270283273(a)atrCDBarrtttalActaM274approximatly20nmtoaoidaffctingthGBconfigurationForGBmobilitysimulations,thstructurwasstraindinsimplsharalongthdirctionnormaltothtiltaxis(parallltoGBplan)atsralconstantstrsssThMDsimulationrsultswranalyzdiaintrfacialdfctthory,whichisbriflyprsntdinAppndixA3Rsultsanddiscussion31ExprimntalThgrainorintationspradcanbusdtoidntifythparntandrcrystallizdgrainsThgrainorintationspradhastwosharppaks:alowstrainpakandahighstrainpakatapproximatly05�and105�,rspctilyThspakswrusdtodistinguishbtwnrcrystallizdgrainsandparntgrainsinachEBSDdatast(Fig3aandb)Inadditiontothstwopaks,thrwasanintrmdiatspikaround7�,corrspondingtoanintrmdiatstagofrcrystallizationThrcrystallizdgrainsmadupabout40%ofthtotalgrainaraInspctionofthinrspolfigurmaps(IPFs)(Fig3cd)(b)(c)Fig4(a)⟨0001⟩,⟨1010⟩,and⟨1120⟩polfigurscorrspondingtothparntinrspol(c)Inrspolfigursfromthsamdatastsshowtypicaldformdandrcrystallizdxtpartlytransformdto(b)th⟨1120⟩axisfibrtxturinthrcrystallizdgrains(alsosprialia128(2017)270283andpolfigurs(PFs)(Fig4ab)ofachpartitionindicatsthatthparntgrains,longatdinthxtrusiondirction(ED),adoptanarlyprfctfirstordrprismatic⟨1010⟩axisfibrtxturHowr,thrcrystallizdgrainsinanquiaxdmorphologyhatwodiffrnttypsoffibrtxturs:anwlyprpondrant⟨1120⟩axisfibrtxtur(oftndsignatdth⟨a⟩axisfibrtxtur)andaninborn⟨1010⟩axisfibrtxturBothfibrtxtursarslightlyinclindnormaltoED,gnratinga“cylindrical”txturbyirtuofsymmtry(i,atxturwithanaxisofsymmtryaboutthED)Thus,thoralltxturmasurdbynutrondiffractiononalargsamplcorrspondstothtraditional“rod”,orprismatic,txturthatformsuponxtrusionofHCPmtals(Fig2)Thmisorintationandgomtricallyncssarydislocationanalyssaroundgrainmbryos(spottdatarlystagsofrcrystallization)wrfurthrxamindtobttrundrstandthoriginofthtwofibrtxtursThIGMAanalysiswasconductdinrgionssurroundingthDRXgrains,ralingprdominantagglomrationofprismatic⟨a⟩typGNDs(lightgrnlinsinFigs5and6)withthdistinguishingcharactristicofth½0001�Tayloraxis(Tabl1)ThsGNDsshowthatthsgrainsoriginatdfigurmap(b)PolfigurscorrspondingtothrcrystallizdinrspolfigurmaprusiontxtursNotth(a)sharp⟨1010⟩axisfibrtxturofthparntgrains,whichadalongthERDdirction)AdministratorHighlightatrCDBarrtttalActaMbygraduallatticrotationaroundth[0001]pol,mblmaticofthCDRXmchanismInthIPFmapofFig5,whichwasobtaindonasctionnormaltoED,grainswiththr⟨a⟩axisfibrtxturswrdtctdatanarlystagofnuclationAxisanglmisorintationanddirctcrystallatticmappingraldthatthgrainorintationofthsnuclihadarotationanglofapproximatly30�aroundth½0001�polwithrspcttothirparntgrainsMoror,thtracofthcorrspondinggrainboundarisshowthatitwasparallltothprismplansofboththparntandrcrystallizdgrain(normaltobothbasalplans)PrformingthsamanalyssonIPFsctionsbothnormalandparallltoEDralthatthbasalplansofthparntandDRXgrainwrallnarlyparallltothEDandthatthbasalplansintrsctdthgrainboundaryplanatnarlyarightangl,ralingthatthz30�½0001�misorintationrlationshipindicatsagrainboundaryoftiltcharactr(Fig6)Asimilaranalysisshowsthatth⟨1010⟩axisfibrtxturrsultdfromCDRXgrainsthatformdfromabundantbasal⟨a⟩andor2ndordrpyramidal⟨cþa⟩GNDsbygradualrotationFig5Inrspolfigurmapofaparntgrain(blu)whrarlynuclationntsofthroffullyrcrystallizdgrainsThrdlinsrprsntboundariswith⟨1011⟩rotationsof3�,linscorrspondto½0001�rotationsof3�inducdbyf1010g⟨1120⟩slipBothhighlightoccurringiarotationsabout½0001�Thisrotationisconfirmdbythpolfigursofthtransitoryorintation(turquois)Thtracofboundaryplans(indashdblacklins)ofalboundary,whichisaf4310gtwinboundary(insolidwhitlins)(Forintrprtationofthrarticl)ialia128(2017)270283275aroundthircommon⟨1010⟩charactristicTayloraxis(rdlinsinFigs5and6)Thrfor,allofthsgrainsrlattothirparntgrainbyth⟨1010⟩rotationaxisThtypsofgrainboundarisobsrdcanalsoshdlightonthDRXmchanismThrwrtwomajormisorintationangldomains(Fig7)Thfirstdomainhasmisorintationanglsinthrangof15�35�,whichxclusilyrlatstonwrcrystallizdgrainswithanaragGOSof5�7�,incontrasttoGOSinthirhailydformdparntgrainsof12�Thsconddomainhasmisorintationanglsinthnarrowrangof63�65�,butthsgrainsarcomprisdoffullyCDRXgrainswithGOSlssthan1�(Fig7ab)SincthrotationaxisforthisdomainwasparallltobothEDandthboundaryplan,allofthsCDRXgrainsartiltboundarisIntrstingly,thIPFmapsshowthatgrainswithth⟨a⟩axisfibrtxturgrowmuchlargrthanthir⟨1010⟩axiscountrparts(Fig8ab)Closinspctionofthgrainboundarisofthlarggrainswithth⟨a⟩axisfibrtxtursuggststhatthyarabnormalgrainsinthprocssofconsumingthirsurroundingsrcrystallizdgrainsof⟨a⟩axisfibrtxturwrdtctdandisolatdfromthrstsothycorrspondtoithrð0001Þ⟨1120⟩andorf1122g⟨1123⟩typGNDsThgrndnucliarsurrounddwithsubstantialf1010g⟨1120⟩GNDsconsistntwithCDRXthrpointstaknfromthparnt(blu),thrcrystallizdgrain(grn),andinalnucliarlongatdinadirctionthatcoincidsinaragwiththtracofaP13afrncstocolourinthisfigurlgnd,thradrisrfrrdtothwbrsionofthisAdministratorHighlightAdministratorHighlightAdministratorHighlightAdministratorHighlightAdministratorHighlightthtdindforCDBarrtttalActaMatrialia128(2017)270283276(Fig8a)Sizhistogramsraldthatahigholumfractionofgrainswithth⟨a⟩axisfibrtxturhagrainsizsthatsurpassd400mm2,whilgrainswithth⟨1010⟩axisfibrtxturdidnothaanygrainslargrthan100mm2Thdiffrncingrainsizisarsultofasubstantiallyhighrmobilityofthgrainboundarisassociatdwiththz30�½0001�misorintationrlationshipcompardtoboundarisassociatdwithgrainsthathath⟨1010⟩axisfibrtxturThrartwomchanismsproposdinthlitraturthataccountforDRXinMg:continuousDRX[8486]anddiscontinuousDRX[8789]ThprdominantrcrystallizationmchanismofMgblow500�Cisaplasticspinmchanismwhrbythdislocationsarrarrangdintohighdnsity,lowanglgrainboundaris(GBs)Fig6InrspolfigurmapofthxtrusionnormaldirctiononasctionparallltotxturhighlightdbythunitcllinrlationtothirparntgrainunitcllThlongacharactrThcomprssidirctionduringxtrusionlisonthbasalplans,thtwoth⟨1010⟩axisfibrtxtur,thrbyrndringitastabltxturcomponntinthdThslowanglboundarisprogrssilyrotatsuchthatthmisorintationincrasscontinuously[8486]andnodistinctstagsofrcrystallizdgrainnuclationandgrowthcanbidntifid,sothisisidntifidasCDRXIncontrast,adiffrntmchanismissomtimsobsrdwhrpartofanxistingGBprotrudstowardthgraininwhichthdislocationdnsityishighrthanthnighboringgrainonthothrsidThdriingforcofthisprocssisthrductionofdislocationdnsityinaDRXgrain,diffrntfromthrmodynamicallydrinGBmigration[90]Thisprocss,whichbcomsmorcommonathighrtmpraturs,hasdistinctnuclationandgrowthstagsandthusisidntifidasDDRXDRXinMganditsalloyshasbninstigatdinanumbrofxprimntalstudiswhrithasbncorrlatdwithtmpraturdpndntdformationmods[84,85,9193]PastworkhasxamindthmchanismsassociatdwithcontinuousDRXanddiscontinuousDRXForinstanc,SitdikoandKaibysh[91,93]instigatdDRXofMgincomprssionorawidrangoftmpraturs(20�C500�C)andaconstantstrainrat3�10�3s�1Thyfoundthatbtwn20�Cand300�C,dformationtwinningplaysanimportantrolwhrbygrainnuclirsultfrommutualintrsctionofprimarytwinsandorscondarytwinsBtwn250�Cand500�C,CDRXdominatsiagrainnuclationbysubgrainrotationAt450�C,grainboundary(GB)bulgingalsooccursiaparntGBmigrationincoarsgrainsInaddition,thprxistingannalingtwinboundariscanalsooltolarganglboundarisandthnmigratbythbulgingmchanism[94,95]Additionally,Iontal[84]studidthDRXofMg08Al%alloyundrcomprssionbtwn150�Cand370�Catastrainrat10�5s�1Thyassumda“rotation”mchanismofDRX,whichxplaindthphnomnonof“ncklac”grainsinMgMoror,Galiytal[85]suggstdothrDRXmchanismsbasdonxprimntalrsultsofMgcomprssionbtwn150�Cand450�CAtlowtmpraturs(blow200�C),DRXisassociatdwiththcombindoprationoftwinning,basalslipand⟨cþa⟩slip;btwn200�Cand250�C,CDRXdominatsiacrossslip;andathightmpraturs(btwn300�Cand450�C),bothbulgingandsubgraingrowthplayacrucialrolinDRXTh“rotationrcrystallization”mchanismdosnotoffraxtrusiondirctionandcontainingtworcrystallizdgrainmbryosofth⟨a⟩axisfibrnuclialongthxtrusiondirctionsuggsta30�½0001�grainboundaryofmostlytiltpndntariantsofprismaticmodarmutuallybalancdforthgrainsaligndwithmdstat[4]compllingxplanationinMgforwhynuclationandgrowthalwaysprocdsinafashionthatonlyafwtypsofgrainorintationsarstablInparticular,thxtrusioncasinMgladsto:1Transformationofthsharp⟨1010⟩����EDfibrtoanw⟨1120⟩����EDtxturcomponntiathformationofaGBthatcanfacilitatamisorintationofabout30�aroundth[0001]polThistiltGBhasahighmobility,rsultinginthcorrspondinggrainsgrowingmuchlargrthangrainswithth⟨a⟩axisfibrtxturAftrfurthrgraingrowthduringscondaryrcrystallization,thisorintationconsumsthothrorintationsandultimatlymaksupthonlystabltxturcomponntofthalloyImportantly,thisGBhasatracnormaltothbasalplanofthparntandrcrystallizdgrainsAssuch,itmaycorrspondtothS13aboundarywhichwasthmostcommonlyrportdGBinconnctionwithrcrystallization[96]Forinstanc,Ostapots[97]hasstudidthisboundarywithsralintrfacanglsrangingfrompurscrwtothfirstofthsymmtrictiltconfigurations(i,f7520g����f2570gandf4310g����f1340gsymmtrictiltGBs,rspctily)AsourEBSDanalyssindicatatiltcharactr,itmostliklycorrspondstothf4310gtwinboundaryInfact,thistwinisa14�[0001]symmtrictiltboundaryaccommodatingamisorintationof28�withthadjacntgrain,whichisclostoth30�misorintationanglstimatdbythEBSDaxisanglmasurmntsFurthrmor,thsixarianttracsofAdministratorHighlightAdministratorHighlightAdministratorHighlightAdministratorHighlightAdministratorHighlightAdministratorHighlightAdministratorHighlightFig7(a)InrspolfigurmapalongasctionnormaltoERDshowingancklacofDRXgrainsformingatthboundarybtwntwoparntgrainsThlfthandsidparntgrainisbingalsoconsumdbylarggrainswithan⟨a⟩axisfibrtxtur(ingrn)undrgoingabnormalgraingrowthThrdlinsrprsntboundariswith⟨1011⟩rotationanglsof3�(b)Thhighlightdrgionin(a)isnlargdtoidntifythGBsofthDRXmbryosThparntgrainonthrighthandsiddlopsnwsmallDRXgrainswhilthparntgrainonthlfthandsidhadDRXgrainsthatgrwmuchbiggrAstablDRXmbryowithth⟨1010⟩axisfibrtxturcanadopt15�35�misorintationanglsaroundth⟨1010⟩polUpongrowth,allDRXgrainswith⟨1010⟩axisfibrtxturntuallydlopdGBswithmisorintationanglsclosto63�aroundthsampolThblacklinscorrspondtohighangl⟨1010⟩boundariswithrotationsinthrangof63�65�Thyllowlinsrprsnthighangl⟨1010⟩boundariswitharotationanglrangof15�35�Thf1121gandf1122glatticplantracsarindicatdinyllowandblackcolorsrspctily(Forintrprtationofthrfrncstocolourinthisfigurlgnd,thradrisrfrrdtothwbrsionofthisarticl)CDBarrtttalActaMatrialia128(2017)270283277atrCDBarrtttalActaM278thisboundaryplanarplottdonbothnormalsctionsinFigs5and6narthdtctdgrainmbryoswithth⟨a⟩axisfibrtxtur,indicatingthatnarlyallofthtwintracsarparallltothboundaryplantracsClarly,thformationofthgrainswithth⟨a⟩axisfibrtxturisinfluncdbythcharactristicsofthisspcialboundary,whichhasamuchlowrnrgyconfigurationforthsgrainorintationsduringCDRXMoror,thisboundaryhasanatomicstructurthatimpartsahighmobilityundrthactionofstrssandtmpratur(showninSction4),andhncprsistsinthmicrostructurbydynamicallyconsumingthlasticstordnrgyinthsurroundingdislocationsubstructursToralaformalundrstandingofthrolofthisGBondynamicrcrystallization,Sction4analyzsallth[0001]symmtrictiltconfigurations,aswllasthatomicstructurofthf4310gtwinboundaryanditsmomntundrstrss2Th⟨1010⟩����EDfibrtxturcontinustoprsistwithinthmicrostructurbymainlyformingtwocatgorisof⟨1010⟩tiltGBsThfirstcatgoryhasmisorintationanglsinthrangof(a)(c)Fig8Inrspolfigurmapsshowinggrainswith(a)⟨a⟩axisand(b)⟨1010⟩axisfibrtgrainaradistributionshowsthhighrgrowthratsofth⟨a⟩axisfibr(grn)compardfibrtxturarconspicuouslylargrinsizthanthircountrparts,indicatingahighrmoofthrfrncstocolourinthisfigurlgnd,thradrisrfrrdtothwbrsionoialia128(2017)27028315�35�andcorrspondsmostlytograinmbryosintharlystagofgrowthThscondcatgoryhasmisorintationanglsbtwn63�and65�Howr,allthsthr⟨1010⟩axisfibrorintationsultimatlycollapsdaftrfurthrgraingrowthduringscondarystaticrcrystallizationClarly,th⟨1010⟩axisfibrmisorintationsardistributdincorrlationtothfirstlownrgymisorintationcatgorisofsymmtric⟨1010⟩tiltboundarisUsingMDsimulations,WangandByrlin[98]showdthatGBswithmisorintationsbtwn0�and33�haGBnrgislowrthan250mJm�2bforasharpcuspisrachdat3424�corrspondingtothsingularf1121gtwinboundarywithaGBnrgyof71mJm�2Actually,thismisorintationwasfrquntlyobsrdforgrainmbryosofthfirstmajorcatgoryof⟨1010⟩tiltGBsThisnrgycuspisrapidlyfollowdbyanothrnrgycuspwhrthnrgydcrassfrom300mJm�2to123mJm�2Thiscuspcorrspondstothf1122gtwinboundarywithamisorintationanglof6328�ItisclarthatallthGBsofthscondcatgory(misorintationanglsbtwn63and65�)corrspondtothis(b)xturs,isolatdfromthrstofthmicrostructurofthsamscanndara(c)Thtoth⟨1010⟩axisfibr(blu)Thabnormalgraingrowthinthgrainswithan⟨a⟩axisbilityofthassociatdz30�[0001]grainboundarymisorintation(Forintrprtationfthisarticl)atrCDBarrtttalActaMtwinmodGBmisorintationanglsgratrthan65�wrscarcinthrcrystallizationtxtur;thiscanbxplaindbythsubstantialGBnrgyincrasatmisorintationanglshighrthanthf1122gtwinboundary,whichhanrgisthatincrasfrom123mJm�2to400mJm�2,prntingfurthrgrainrotationsThatomicGBstructurandnrgisofsinq=20cosq=2¼0@cosq=20sinq=20101A(3)Fig9Plotofth[0001]symmtrictiltgrainboundarynrgisasafunctionofmisorintationanglinmagnsiumThGBnrgyincrassrapidlywithmisorintationanglasthanglincrassfromzroAsmallS7cuspinnrgyoccursat22�ThGBnrgypaksatabout330345mJm�2onithrsidofadprS13acuspat28�Thpotntialnrgydcrasspast30�downto0mJm�2at60�,withnrgycuspsat34�and38�fromthS13aandS7nrgyminima,rspctilyFig10(a)ThDichromaticComplx(DC)ofthS13aboundaryshowingthatitcorrspondsto14�[0001]tiltf1340gcompoundtwinintrfacofTypIThatomicstructurofthtwinintrfaccouldbsnasanarrayofrotatdprismaticdislocations,andthata2DDRXmbryocanbformdbyasimplagglomrationofa2Darrayofprismaticdislocations,mdiatdbyazrostrngthdisclinationThisagrswllwiththrsultsofIGMAanalyssonthEBSDscansThtwincaninprincipalgrowbyab2=2disconnctionwithazrontshuffl(b)MDsimulationrsultsshowingthrlaxdatomicstructurofthboundaryandtharrayofrotatdprismaticdislocations�sinq=20cosq=2Dfiningl¼ðl;0;0Þ,andb¼ð0;0;bÞwhichisconninttoth⟨1010⟩symmtrictiltGBshabnstudidindtailbyWangandByrlin[98],sothywillnotbaddrssdhr32ModlingUsingMDsimulations,wcomputdthnrgylandscapofthsymmtric½0001�axisboundaris,withmisorintationanglsthatrangfrom0�to60�Thisisthcompltrangofuniqusymmtric½0001�axisboundaris;anglsfrom60�to120�aridnticaltothosrangingfrom60�to0�Atotalof30GBswrconstructdandanalyzdinthisrangwithanapproximatly2�misorintationstpRsultsofGBnrgisarillustratdinFig9Incontrasttoth⟨1010⟩symmtrictiltGBs,thmaximumnrgyiswllblow350mJm�2ThsingularGBsoccuratnrgycuspsblow250mJm�2Twomainpairsofnrgyminimaarobsrd:thS13aboundaristhatoccurat28�and34�misorintationangls,andthshallowcuspofthS7boundarisat22�and38�Fig9ralsthatS13aisthsymmtrictiltGBaround30�thatisthmostliklycandidatboundaryforstabilizingthDRXgrainmbryoandprntingfurthrrotationLowrsymmtryCSLboundaris,suchasthS19GB,didnotproducanynoticablcuspsinthnrgydistributionFig10aandbshowsthdichromaticcomplx(DP)andthatomisticallycalculatdGBstructurofth28�misorintdS13aboundary,rspctilyFig10ashowsthatthboundaryappndsf4310gplans,whichcorrspondtoacompoundTypItwinintrfachaingK2asthð0110ÞfirstordrprismaticplanHrK1andK2rfrtothstandardtwinninginariantplans[11]ItisimportanttonotthatthisintrfaccanalsobiwdasquialnttoarotatdarrayofprismaticdislocationsAssuch,thboundarycouldarisfroma2Dagglomrationofsuchadislocationarray,asillustratdinthdichromaticcomplxofFig10aFig10bxhibitsthrlaxdatomicstructurofthisboundaryobtaindbyMDsimulationsThprismaticdislocationwallhasbndrawninthisrlaxdstructur,corroboratingthdislocationiwofthboundaryThrotationanddislocationdnsitymaybrlatdbythclassicalformulationginbyHirthandLoth[99]:l¼b2sinðq=2Þ(1)whrlisthdistancbtwndislocations,andqisthmisorintationanglofthboundaryThisquationcanbdridfromthFrankBilbyquationwiththappropriatchoicsofAmandAl,whicharaffindformationtnsorswhichmapmandltothrfrncsystm:b¼�Am�Al�l(2)AmandAlardfindhrsuchthatAm¼Tm,andAl¼Tlandthrfrncsystmisasinglcrystalwiththprismaticplansofbothlatticsaligndwiththðx�yÞplan:Am¼0@cosq=20�sinq=20101A;Alialia128(2017)270283279casofthisstudy,gis:0gtw)watrb¼2lsinq=2(4)ForthcasofS13aboundary,thmisorintationisginby:q1¼cos�12326;q2¼p6�cos�12326;(5)Notably,sincthmisorintationanglof60�isalsoquialnttoasinglcrystal,thmisorintationofthS13aboundarymaybdfindbybothq1andq2BcausthdislocationmodlofthS13aboundaryussprismatic⟨a⟩dislocationsnormaltothboundary,q2shouldbthappropriataluThlimitofthmisorintationasthprismatic⟨a⟩dislocationdnsitygostozroisat60�,not0�,inourconstructionNotingthatthcohrntdichromaticpattrn(CDP)[100]forthissituationisasinglcrystalchromaticpattrn,andthnaturaldichromaticpattrn(NDP)aswllasrotatdCDParthsampattrnshowninFig10a,throtationrstoringdislocationsarprismatic⟨a⟩dislocationsnormaltothboundaryThusb¼aSolingforlgis:l¼affiffiffiffiffiffi13p(6)Fig11(a)MDsimulationimagsofsimplsharapplidalongth14�[0001]tiltf134Thboundaryhasahighmobilityowingtothb2=2disconnctionwithawidcor(bCDBarrtttalActaM2802ForthS13a,thisaluhassignificancfortworasonsOnonhand,thintrplanarspacingofthprismaticplansalongthboundaryisl=2Thrfor,thboundaryiscomposdofadislocationarraywithadnsityofondislocationforryothrprismaticplanOnthothrhand,thdistancbtwnnarstcoincidntpointsinthboundaryapartfromthosalongthtiltaxisis2lAsmntiondpriously,unlikthdislocationarraybasddscription,thS13aboundarymaybbstconsidrdtohathcorstructurofthtwinThisprfrncisjustifidbythprsncofacuspinthnrgylandscap,indicatingthatthboundarycorstructurisnotfullydfindbyadislocationarrayUsingthisdscriptionwithadichromaticcomplx,mobildisconnctionsmdiatingtwinintrfacmigrationmaybidntifidFig11adpictsasnapshotofanMDsimulationwhrsharstrainhasbnapplidtothboundaryThstrainwasmonitordinafashiontokpthboundarymoingatroughlythsamlocityStrikingly,thrquirdstrssswasapproximatly40MPa,whichisxtrmlylowwhncompard,forinstanc,to400MParquirdtostadilymothf1012gtwinintrfacinanMDsimulation[79](Itshouldbnotdthatdutostrainratandscalffcts,thactualcriticalrsoldsharstrsssforbothboundarisarmuchlowrthanthalusmasurdinthsatomisticsimulations)ARHFSBurgrscircuitdrawnaroundthintrfacralsaglissilb2=2disconnction,whichhasawidcorofapproximatly20a,accommodatingasharof058(Fig11b)Thiswidcorisalsoastrongindicatorofrmarkablabilitywhncompardtoothrsimilarintrfacialdisconnctioncorwidthssuchas6aforf1012gtwinningand11aforf1121gtwinning[101]ThBurgrsctorandstphightofthactidisconnctionwrobtaindtob:b2=2¼0@�affiffiffiffiffiffi13p001A¼AmlmþAmlll;lm¼h1010i;ll¼23h2110i(7)Thtwindirctionalongxis½7520�Thstphighthandsharsaranalyticallyginas:h¼Amlm5bz¼Alll5bz¼affiffiffiffiffiffi313r;s¼���b2=2���h¼�1ffiffiffi3p(8)inboundarynormaltothtiltaxisandataconstantsharstrssamplitudof40MPahichwasconfirmdbythRHFSBurgrscircuitialia128(2017)270283ThhighmobilityofthistwinboundaryisinagrmntwiththrsultsofEBSDanalysisshowingxcssigrowthofgrainswithth⟨a⟩axisfibrtxtur(Fig7a)ItalsosuggststhatassoonasthrotationrcrystallizationbythrotatdarrayofthprismaticdislocationculminatstoformthS13aboundary,xcssigraingrowthtaksplactoconsumthntirmicrostructurasdpictdinthIPFmapofFig8a4ConclusionsElctronbackscattrddiffractioncharactrization(EBSD),molculardynamic(MD)simulations,andintrfacialdfctthorywrconductd,incombination,toundrstandthoriginoftxturformationinanxtruddAM30MgalloyThrsultssubstantiatthatDRXgrainswithth⟨a⟩axisand⟨1010⟩axisfibrtxturoriginatfromthtndncyofrotationrcrystallization(CDRX)tosttlatsingulargrainboundarisshowingsubstantialnrgyminimaandhighmobilityspiks,ralingthatgrainboundaryproprtisarafundamntalpicofthpuzzlindynamicrcrystallizationofMgInparticular,thfollowingphnomnaarobsrdinthisstudy:ofmisorintationanglsblow34Thistndncyhasbncorrlatdtothlownrgyplatauinthnrgylandscapofth⟨1010⟩symmtrictiltGBs,whichcuspsat3424�misorintationanglfaturingthf1121gtwinningInthscondplan,whichisinagrmntwiththobsrdGNDswiththir½0001�TayloraxisinEBSDHowr,asubstantialnrgycuspwasidntifidinthnrgylandscapofth[0001]byMDlmmatrsimulations,suggstingthatth28�misorintationanglcanbrgarddasthf1340gTypIcompoundtwinintrfacwithK2¼ð0110Þ5Azrontshufflb2=2disconnctionwithawidcorwasidntifidbyMDsimulationstoaccommodatahighmobilityoff1340gtwinboundaryThisfindingisinstrikingagrmntwiththabnormalgraingrowthofth⟨a⟩axisfibrgrains,tndingtoultimatlyconsumthntir⟨1010⟩axisfibrgrainsaftrsubstantialgraingrowthThsignificancofthisstudyisthatitralsthimportancofgrainboundarynrgyandmobilityffctsontxturformationduringdynamicrcrystallizationofMgathightmpratursAcknowldgmntsRsarchwassponsordbythArmyRsarchLaboratoryandwasaccomplishdundrCoopratiAgrmntNumbrW911NF1520025Thiwsandconclusionscontaindinthisdocumntarthosofthauthorsandshouldnotbintrprtdasrprsntingthofficialpolicis,ithrxprssdorimplid,ofthArmyRsarchLaboratoryorthUSGornmntThUSGornmntisauthorizdtorproducanddistributrprintsforGornmntpurpossnotwithstandinganycopyrightnotationhrinAppndixAIntrfacialdfctthoryInspirdbythworkofVoltra[102]onsinglcrystals,andthatofShubniko[103,104]ongroupsofgnralizdsymmtry,Pond[105]showdthatadmissiblintrfacialdfctscanbcharactrizdbyproprcombinationofsymmtryoprations(proprorimpropr),onfromachofthtwocrystalsdsignatdbyblack,m,stag,thGBmisorintationanglincrasstoaround63�angl,narth6328�misorintationanglassociatdwithf1122gtwinning3Thgrainswithth⟨a⟩axisfibrtxturarproducdbysubgrainsthatbuildupbyaccumulationofgomtricallyncssarydislocationswith½0001�Tayloraxis,mostliklycorrspondingtoprismatic⟨a⟩dislocations4RotationofthssubgrainsalmostxclusilyformsGBswitha28�misorintationangl,mostliklycorrspondingtothS13aboundarisaccordingtothcoincidntsitlatticthoryThdichromaticcomplxshowsthatthisboundarycouldbiwdasrotatdarraysofprismaticdislocationsoccurringryothr1Grainswithth⟨1010⟩axisfibrtxturformfromsubgrainsthatbuildupbyaccumulationofgomtricallyncssarydislocationswith½1010�Tayloraxis,mostliklycorrspondingtobasal⟨a⟩dislocationsandpyramidal⟨cþa⟩dislocations,2ThssubgrainsolbythnsuingrotationintwostagsInthfirststag,thytndtoformgrainboundariswithamyriad�CDBarrtttalActaMandwhit,l:Vint¼Wm�Wl��1;Wm¼½FmjamþRm�andWl¼hFl���alþRli(A1)hr,WrfrstoasymmtryoprationinthhostcrystalspcifidbythsuprscriptandblongstothFdrospacgroup(HCPinthisproposal)[103]Fdnotsapointgroupopration,whilarfrstothsupplmntarynonlatticdisplacmntassociatdwithF(c2inHCP)RisalattictranslationUsingthSitz[106]symbol,whnWactsonactorr,thlattrtransformsto:Wr¼½FjaþR�r¼FrþaþR:(A2)ThquasismidirctproductdfinsthmultiplicationlawofthFdrogroup:WmWl¼½FmjamþRm�hFl���alþRli¼hFmFl���Fm�alþRl�þamþRmi(A3)So,Wm�Wl��1¼hFmAFl�1A�1����FmAFl�1�A�1þalþRl�þFmtþamþRmi(A4)½Ajt�isthoprationthatconrtsthwhitlatticltoblacklatticm,whrAisalinartransformationmatrixThsuprscript“1”dnotsthinrsofthoprationinthsnsofgroupthory,thatis:½FjaþR��1¼hF�1����F�1a�F�1Ri(A5)ThdirsityofintrfacialdfctsprdictdbyEq(A1)dpndsonhowoftnthadjacntcrystalsxhibitcommonsymmtrisladingtoVint¼½Ij0�whichshallbrmodHr½Ij0�isthidntitylmntofthFdrogroup,andIisthidntitymatrixHowr,oncandistinguishingnralfitypsofdfcts:DSCdislocations,arisingwhnbothWmandWltakthsimpl½IjR�formEq(A4)bcoms:Wm�Wl��1¼½IjRm�hI���Rli¼hI���Rm�ARli(A6)ThBurgrsctorbcoms:bg¼Rm�ARl(A7)SupplmntarydisplacmntdislocationsarisingwhnthnonlattictranslationaintrnsinatlastonofthtwocrystalsForsimplicity,ltRm¼Rl¼0inEq(A4)Toobtainadislocation:Wm�Wl��1¼½Ijt�0Fm¼AFlA�1(A8)ThismansthatFmandFlarcoincidntoprationsinthdichromaticcomplx(DC),andassuch:Wm�Wl��1¼hI���al�AamþðFm�IÞti(A9)Hnc,thBurgrsctorwrit:ialia128(2017)270283281bg¼a�AaþðF�IÞt(A10)AdministratorHighlightcssfulinidntifyingthlinorintationandBurgrsctorofatrdfctsatintrfacssparatingdissimilarcubics[107,108]Rfrncs[1]MEaston,ABr,MBarntt,CDais,GDunlop,YDurandt,SBlackt,THilditch,PBggs,Magnsiumalloyapplicationsinautomotistructurs,JOM60(no11)(No2008)57[2]AALuo,Magnsium:currntandpotntialautomotiapplications,JOM54(no2)(Fb2002)4248[3]BLMordik,TEbrt,Magnsiumproprtisapplicationspotntial,MatrSciEngA302(no1)(2001)3745[4]JHirsch,TAlSamman,Supriorlightmtalsbytxturnginring:optimizdaluminumandmagnsiumalloysforautomotiapplications,ActaMatr61(no3)(Fb2013)818843[5]SRAgnw,Wroughtmagnsium:a21stcnturyoutlook,JOM56(no5)(May2004)2021[6]RERdHill,WDRobrtson,Pyramidalslipinmagnsium,TransMtallSocAIME221(1958)256259[7]SRAgnw,€ODuygulu,PlasticanisotropyandthrolofnonbasalslipinmagnsiumalloyAZ31B,IntJPlast21(no6)(2005)11611193[8]JKoik,TKobayashi,TMukai,HWatanab,MSuzuki,KMaruyama,KHigashi,ThactiityofnonbasalslipsystmsanddynamicrcoryatroomtmpraturinfingraindAZ31Bmagnsiumalloys,ActaMatr51(no7)(2003)20552065[9]BLi,EMa,Pyramidalslipinmagnsium:dislocationsandstackingfaultonth{1011}plan,PhilosMag89(no14)(2009)12231235[10]ALOppdal,HElKadiri,CNTom�,GCKaschnr,SCVogl,JCBaird,MFHorstmyr,Effctofdislocationtransmutationonmodlinghardningmchanismsbytwinninginmagnsium,IntJPlast3031(2012)4161[11]JWChristian,SMahajan,Dformationtwinning,ProgMatrSci39(no12)(1995)1157[12]MMyrs,OV€ohringr,VLubarda,Thonstoftwinninginmtals:aconstitutidscription,ActaMatr49(no19)(2001)40254039[13]MRBarntt,Twinningandthductilityofmagnsiumalloys:PartI:‘Tnsion’twins,MatrSciEngA464(no12)(2007)17[14]MRBarntt,TwinningandthductilityofmagnsiumalloysPartII‘Contraction’twins,MatrSciEngA464(no12)(2007)816[15]LMng,PYang,QXi,WMao,Analyssoncomprssiontwinsinmagnsium,MatrTrans49(no4)(2008)710714[16]SRAgnw,DWBrown,CNTom�,ValidatingapolycrystalmodlforthRlaxationdisplacmntdislocationsarisingwhnarigidbodydisplacmnttoccursaspartofthrlaxationprocssthatcannotbprdictdbycrystallographyanalyssForgrainboundaris,tmaybrakanantisymmtryopration,andthus,adfctwillsparatdgnratstructursIntrfacialdisclinationsgnrallyarisinginfacttdintrfacswhnam¼Rm¼al¼Rl¼0,soEq(A4)bcoms:Wm�Wl��1¼hFmAFl�1A�1����FmAFl�1A�1þFmti(A11)WmðWlÞ�1mustbapropropration,andthdisclinationrquirssomdislocationcharactr(Frankctor)inthprsncofarigiddisplacmntt:b¼Fm�I�AFl�1A�1�t(A12)Intrfacialdispirationsarisingfornonsymmorphiccrystals(likHCP),whronlyRm¼Rl¼0Thus,adispirationhasbothadisclinationanddislocationcharactrnfort¼0Eq(A4)thusbcoms:Wm�Wl��1¼hFmAFl�1A�1����FmAFl�1�A�1þal�þFmtþami(A13)ThabilitytocarryoutdisrgistryanalyssinMDsimulationsisworthmntioninginthcontxtofIDTDisrgistryisdfindasthdisplacmntrlatitoarfrncspacofrylmatompairacrossthintrfacAllowingdriingfinlyrsoldinformationondfctsanddfctractions,disrgistryhaspronsucCDBarrtttalActaM282lastoplasticrsponsofmagnsiumalloyAZ31usinginsitunutrondiffraction,ActaMatr54(no18)(2006)48414852[17]HYoshinaga,RHoriuchi,Dformationmchanismsinmagnsiumsinglcrystalscomprssdinthdirctionparallltohxagonalaxis,TransJpnInstMt4(no1)(1963)18[18]ZBasinski,Thinfluncoftmpraturandstrainratonthflowstrssofmagnsiumsinglcrystals,AustJPhys13(1960)284[19]SRAgnw,PlasticanisotropyofmagnsiumalloyAZ31Bsht,EssntRadMagnsTchnol(2002)351356[20]FKaisr,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Effctofgrainboundarisontxturformationduringdynamicrcrystallizationofmagnsiumalloys 1Introduction 2Exprimntalandsimulationmthodology 21Exprimntalalloys 22EBSDanalyss 23Macrotxturmasurmnts 24Molculardynamicsimulations 3Rsultsanddiscussion 31Exprimntal 32Modling 4Conclusions Acknowldgmnts AppndixAIntrfacialdfctthory Rfrncs