多级纳米金属的力学性能-卢柯

Mechanicalpropertiesofhierarchicalnanostructuredmetals多级纳米金属的力学性能卢柯中国科学院金属研究所，沈阳材料科学国家（联合）实验室“钱学森讲座报告”中国科学院力学研究所,2013-09-12•Increasedstrength•Reducedductility•Reducedwork-hardeningNano-grainedmaterials:strongbutbrittleC.C.KochetalMRSBull.(1999)051015202530350100200300400500600700Engineeringstress(MPa)Engineeringstrain(%)Coarse-grainedCuNano-grainedCuD:~30nmnm020040060080010000102030405060Elongation-to-failure,f(%)Tensileyieldstrengthy(MPa)Mixed-structure(100~2000nm)Mixed-structure(20~200nm)Nano-twins(D=400nml=15nm)Coarse-grainedCuNano-grained&Ultrafine-grainedCuTrade-offofstrengthandductilityProcessing-inducedporositiesProcessing-inducedcontaminationStrainlocalizationLackofstrainhardeningWhybrittleundertension?Homogeneousnano-grainedmetalsDislocationmotion:suppressedGBslidingorcreep:nodirectevidenceOthermechanisms:?PlasticdeformationmechanismFullydensesamplesCleansamples??(earlynecking)??(uniformdeformation)Hierarchical(heterogeneous)nanostructuresNano-twinnedGradientnano-grainedHierarchicalnanostructuredmaterialsNano-twinned&m-grainedStraindelocalization&strain-hardeningGBGrain1Grain2Grain1Grain2GBstrengtheningK.Lu,L.Lu,S.Suresh,TBACBABBABCATwinMatrixCCCMatrixMatrixTwinNano-scaleTBstrengtheningResistingdislocationtrans.Capabilityofaccomm.disl.DislocationmobileatTBLowenergy—highstabilityResistingdislocationtrans.Limitedcapabilityofaccomm.disl.DislocationimmobileatGBsHighenergy—lowstabilityStrengthening:GBvsTBatnano-scaleDuctility:toreleasestress/strainlocalizationCross-slipof60ºdislocations(DA)DislocationslipsacrossTBs:AMDsimulationinCuZ.H.Jin,ScriptaMater.(2006);ActaMater.(2008)MMTl~nmMaterialComingDislocationTwinningpartial(Glissiledisl.atTB)AtTBIntwinAlScrew2Shockleypartials----DA(3%)dADd--DA(4%)Cd--A’D’ADdC+AdCD/AB1/2(-1-10)--CuScrew----ScrewDACd--ADAD--i-lockSF+g’A’NiScrew----ScrewDA(1.5%)Dd--dADA(4%)Bdv-lockSF+g’D’AD--i-lockSF+g’A’Dislocation-TBinteractionsinfccmetalsZ.H.Jin,ActaMater.(2008)100nm200nm2nmPlan-viewTEMimages:edge-onTBsPolycrystallineCuwithnano-scaletwinsGrowthSynthesis:pulsedelectrodeposition(PED)02468101214161820040060080010001200ABTruestress(MPa)Truestrain(%)CG-CuIGC-CuCIncreasingtwindensityTensilepropertiesofPEDnano-twinnedCuStrengthANDductilityincreasehand-in-hand!Lu,etal,Science,(2004)16mmOriginalAC~6x10-3s-1Dislocation-TBinteraction:3modesDislocationslip-transferThreadingdislocationsTwinningpartialsT.Zhu&HJGao,ScriptaMater.,2012Hard-IHard-IISoftSlipsystems:twinnedFCCmetalsMatrixMatrixTwinMatrixMatrixTwinMatrixMatrixTwinGBd_BCd_ACd_ABg_ABb_ACa_BCg_DBg_DAb_DCb_DAa_DCa_DB121110987654321HardIHardIISoftDislocationslip-transferThreadingdislocationsTwinningpartialsZ.S.Youetal,ActaMater.,2013Columnargrainswithnano-twinsinCu2mmGDDCelectrodepositionGDLevels(m.u.d.)123450.841.532.222.923.614.304.995.68min=0.17max=6.12Strong{111}out-of-planetexture200nmL.Luetal,ActaMater.,2011Twinthicknesseffectsinnt-Cu2/10lTBykHall-PetchmodelMatrixMatrixTwin)ln(0bbyallmbConfinedlayerslipMatrixMatrixTwinL.Luetal,ActaMater.,2011HardnessofAgthinfilmswithNTsX.H.Zhang,etal,ActaMater.,2011l=9nml=40nmStrengthofCunanowireswithNTsJ.Greer,HJGao,etal,NatureNanotech.,2012StrengthofAunanowireswithNTsS.Maoetal,NatureComm.,201310nm2nmCubicBNwithNTs:harderthandiamondnt-cBNY.J.Tian,etal,Nature,2013Ductilityandwork-hardening:ntCu05101520253035051015020040060080010001200ufgTruestrain(%)Truestress(MPa)nt-15nt-10ufgTruestrain(%)nt-8nt-4cgnt-96nt-35nt-15Lu,etal,Science,(2009)MatrixMatrixTwinGB5nm--Dominatedbytwinningpartials--GB/TBintersections:nucleationsitesHard-IandHard-IITB-latticedislocationinteractionsSoftTwinningpartialsnucleation&slip02040608010012002004006008001000y(MPa)lord(nm)nt-Cunc-CuNano-twinnedCu:MaximumstrengthMatrixMatrixTwinL.Lu,etal,Science,(2009)MatrixMatrixTwinGBHJ.Gao,etal,Nature,(2010)100nm5nmb2nmSFSFSFSF500nmNano-twinnedCu:ultrahighwork-hardeningL.Lu,etal,Science,(2009)Deformedcg-metals:1014~1015m-2r~5x1016m-2cg-Cu:n=0.3502004006008001000y(MPa)051015202530du(%)0204060801001200.00.20.40.6nl(nm)GBStrengtheningStrainhardeningCoeff.Elongation-to-failure(%)Dorl(nm)02004006008001000y(MPa)051015202530du(%)0204060801001200.00.20.40.6nl(nm)TBStrengtheningNano-twinnedCuvsnano-grainedCuK.Lu,L.Lu,S.Suresh,Science,(2009)Nano-grained•Highstrength•Brittle•Reducedwork-hardening•PoorstabilityNano-twinned•Highstrength•Ductile•Enhancedwork-hardening•Highstability@RT,LNTStrainrate:102~103s-1Strainofeachimpact:~0.1AnvilHammerSampleLiquidnitrogenε=ln(Lo/Lf)0.41.11.40W.S.Zhao,etalScriptaMater.(2006)Y.S.Li,etal,ActaMater.(2008)Dynamicplasticdeformation(DPD)Bulksamples:Nano-scaledeformationtwins1mmDPDCu:nano-sizedgrains&nano-scaletwinsCross-sectionalTEM=2.1Y.S.Li,etal,ActaMater.(2008)T/MlamellaeNano-grainsVolume%35%65%AveragesizelT/M=49nmdT=76nmCuNiCuMnCudisCudistwinCuTwinCuECAPCuDrawdisCudrawtCumachindisCumachindtSMGTCurolldisCurollingdtCuHPTdisCucryocomprDisDistwinTwinHong2.2Hong4.5XiaoHPTCuZndtHPTCuZntCRCuZndtCRCuSitCRCuZntCuSndtCuSndCuGetCuAlECAPdtCuAlECAPtCu-Al(presentwork)CRCu-Ni[