A Transforming Metal Nanocomposite with Large Elastic Strain(2)

REPORTS

initiallyalignedwiththisdirectionemittedpurecircularlypolarizedphotonsandremainedin-variantunderscattering.Theirsuperpositions,ontheotherhand,becameentangledwiththescat-teredphotonpolarization.Statesthatareinvariantundercouplingtotheenvironmentareofinterest,notonlybecauseoftheirimportanceinthequan-tummeasurementprocessbutalsobecauseoftheirpotentialuseforquantumcontrolpurposes.Invariantstatescanspandecoherence-freesub-spacesinwhichquantuminformationcanbeprotected(21).Itwouldbethereforeinterestingtosearchformulti-spinstatesthatareinvariantunderphotonscattering,anddetection,byusinglargerarraysoftrappedions.

ReferencesandNotes

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18.Cohen-Tannoudji,ClaudeandDiu,BernardandLaloe,

Frank,QuantumMechanics(Wiley-Interscience2006),Vol.2,p.1048.

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2594(1998).Acknowledgments:Y.G.andS.K.haveequallycontributedtothiswork.WethankN.DavidssonandD.Stamper-Kurnforusefulcommentsonthemanuscript.Wegratefully

acknowledgethesupportbytheIsraeliScienceFoundation,theMinervaFoundation,theGerman-IsraeliFoundationforscientificresearch,theCrownPhotonicsCenter,andM.KushnerSchnur,Mexico.

SupplementaryMaterials

/cgi/content/full/339/6124/1187/DC1MaterialsandMethodsFigs.S1toS4

3September2012;accepted2January201310.1126/science.1229650

17.

ATransformingMetalNanocompositewithLargeElasticStrain,LowModulus,andHighStrength

ShijieHao,1LishanCui,1*DaqiangJiang,1XiaodongHan,2*YangRen,3*JiangJiang,1

YinongLiu,4ZhenyangLiu,1ShengchengMao,2YandongWang,5YanLi,6XiaobingRen,7,8XiangdongDing,7ShanWang,1CunYu,1XiaobinShi,1MinshuDu,1FengYang,1YanjunZheng,1ZeZhang,2,9XiaodongLi,10DennisE.Brown,11JuLi7,12*

Freestandingnanowireshaveultrahighelasticstrainlimits(4to7%)andyieldstrengths,

butexploitingtheirintrinsicmechanicalpropertiesinbulkcompositeshasproventobedifficult.Weexploitedtheintrinsicmechanicalpropertiesofnanowiresinaphase-transformingmatrix

basedontheconceptofelasticandtransformationstrainmatching.ByengineeringthemicrostructureandresidualstresstocouplethetrueelasticityofNbnanowireswiththepseudoelasticityofaNiTishape-memoryalloy,wedevelopedaninsitucompositethatpossessesalargequasi-linear

elasticstrainofover6%,alowYoung’smodulusof~28gigapascals,andahighyieldstrengthof~1.65gigapascals.Ourelasticstrain-matchingapproachallowstheexceptionalmechanicalpropertiesofnanowirestobeexploitedinbulkmaterials.tischallengingtodevelopbulkmaterialsthatexhibitalargeelasticstrain,alowYoung’smodulus,andahighstrengthbecauseoftheintrinsictrade-offrelationshipsamongtheseprop-erties(1,2).AlowYoung’smodulusinasingle-phasematerialusuallymeansweakinteratomicbondingandthuslowstrength.Becauseoftheinitiationofdislocationactivityand/orearlyfail-urecausedbystructuralflaws,theelasticstrainofbulkmetalsisusuallylimitedtolessthan1%.Becausefreestandingnanowireshaveultrahighelasticstrainlimits(4to7%)andyieldstrengths(3–9),itisexpectedthatcompositesmadewithnanowireswillhaveexceptionalmechanicalprop-erties.However,theresultsobtainedsofarhavebeendisappointing(10),primarilybecausethein-trinsicmechanicalpropertiesofnanowireshavenotbeensuccessfullyexploitedinbulkcomposites(10–12).AtypicalexampleistheNbnanowire–Cumatrixcomposite,inwhichthenanowiresare

nanowires,asillustratedinFig.1A.Second,SIMTanddislocationsliparefundamentallydifferentprocessesattheatomicscale.Whereastheinelasticshearstrainbetweentwoadjacentatomicplanesapproaches100%afterdislocationslip(17),theatomic-levelinelasticortransformationstrainis~10%afterSIMTintypicalSMAssuchasNiTi(16).Therefore,inelasticstrainincompatibilities(whichmustbecompensatedforbytheelasticstrainfieldtomaintaincohesion)aremuchmilderattheSMA-nanowireinterfacethanattypicaldislocation–piled-upinterfaces.

Toverifythishypothesis,weselectedNbnanowirestobecombinedwithaNiTiSMA.TheNiTi-Nbsystemwith~20atomic%Nbun-dergoeseutecticsolidificationintoamicrostruc-tureconsistingoffineNblamellae(18),whichcanbeconvertedintoNbnanowiresthroughse-vereplasticdeformation.Inthisstudy,aningotwithacompositionofNi41Ti39Nb20(atomic%)waspreparedbymeansofvacuuminduction

StateKeyLaboratoryofHeavyOilProcessing,ChinaUni-versityofPetroleum,Beijing102249,China.2InstituteofMicrostructureandPropertiesofAdvancedMaterials,BeijingUniversityofTechnology,Beijing100124,China.3X-raySci-enceDivision,ArgonneNationalLaboratory,Argonne,IL60439,USA.4SchoolofMechanicalandChemicalEngi-neering,TheUniversityofWesternAustralia,Crawley,WA6009,Australia.5StateKeyLaboratoryforAdvancedMetalsandMaterials,UniversityofScienceandTechnologyBeijing,Beijing100083, …… 此处隐藏：5405字，全部文档内容请下载后查看。喜欢就下载吧 ……