Mechanical properties Characterization of Materials at Multiple Scale
Title：MechanicalpropertiesCharacterizationofMaterialsatMultipleScaleReportor:Prof.QianYuZhejiangUniversityTime:2016年9月7日(周三)9:30-11:00 Address：中科院力学所1号楼344会议室Abstract：Traditionalmechanical/electrical/thermaltestingexperimentsandmaterialcharacterizationtechniquesarefrequentlyseparate,sotheylackthein-situinformationresolutionrequiredtodirectlyrelatethemeasuredpropertieswithindividualmicrostructureevolutionevents.Thebroadfieldofelectronmicroscopyinstrumentationdevelopmentholdsgreatpromiseforaddressingtheseproblemsduetoitsinherentlyhighspatialresolutionandthestronginteractionsbetweenelectronsandsolids.Itisbelievedtobetheidealtooltoexploitmaterialsproperties,especiallyatsmallscale.Here,IwillpresentrecentresultsinvestigatingmaterialspropertiesatmultiplescalesbycouplingtheinsituTEM/SEMtechniqueswithothercharacterizationtechniquessuchasHRTEMandEBSD.Forinstance,byusingtransmissionelectronmicroscopyandnanomechanicalcharacterization,wereportthattheintensehardeningeffectofdiluteoxygensolutesinpurea-Tiisduetotheinteractionbetweenoxygenandthecoreofscrewdislocationsthatmainlyglideonprismaticplanes,whichwasthoughtunlikelybasedontraditionalunderstandingofsolidsolutionstrengtheningmechanisms.Alsowestudiedthedeformationmechanismsthatareresponsiblefortheultra-hightoughnessofhighentropyalloys.Wereportonthesalientatomistictomicro-scalemechanismsunderlyingtheoriginoftheseproperties.Weidentifyasynergyofmultipledeformationmechanisms,rarelyachievedinmetallicalloys,whichgenerateshighstrength,workhardeningandductility,includingtheeasymotionofShockleypartials,theirinteractionstoformstacking-faultparallelepipeds,andarrestatplanarslipbandsofundissociateddislocations,inFeCoNiCrMn.Wefurthershowthatcrackpropagationisimpededbytwinned,nanoscalebridgesthatformbetweenthenear-tipcrackfacesanddelayfracturebyshieldingthecracktip.Biography：Dr.QianYureceivedherB.S.degreeandM.S.degreeinMaterialsScienceandEngineeringfromXi’anJiaotongUniversityofChinain2006and2009,respectively.ThenshereceivedherPh.DdegreefromUCBerkeleyin2012.From2012to2014,shewasapostdoctoralfellowatLawrenceBerkeleyNationalLaboratorybeforeshejoinedZhejiangUniversity,wheresheiscurrentlyaProfessorinDepartmentofMaterialsScienceandEngineering.Yu’sgroupconductsresearchatthemechanicalpropertiesofmaterialsatmultiplescale,particularlyintheadvancingmaterialsperformanceatthenanoscale.Solidmaterialsareveryimportantmarketconsumesinrealindustryandareholdingtheleadingrolesasstructuralmaterialsandfunctionalmaterials.Regardlessoftheapplication,thedevelopmentofsolidmaterialsisassociatedwithsolidmechanicsandmicrostructurecharacterization.