多級(jí)納米金屬的力學(xué)性能-盧柯

Mechanicalpropertiesofhierarchicalnanostructuredmetals多級(jí)納米金屬的力學(xué)性能盧柯中國(guó)科學(xué)院金屬研究所，沈陽(yáng)材料科學(xué)國(guó)家（聯(lián)合）實(shí)驗(yàn)室“錢(qián)學(xué)森講座報(bào)告”中國(guó)科學(xué)院力學(xué)研究所,2013-09-12IncreasedstrengthReducedductilityReducedwork-hardeningNano-grainedmaterials:strongbutbrittleC.C.KochetalMRSBull.(1999)Coarse-grainedCuNano-grainedCu<D>:~30nmnmMixed-structure(100~2000nm)Mixed-structure(20~200nm)Nano-twins(D=400nml

=15nm)Coarse-grainedCuNano-grained&Ultrafine-grainedCuTrade-offofstrengthandductilityProcessing-inducedporositiesProcessing-inducedcontaminationStrainlocalizationLackofstrainhardeningWhybrittleundertension?Homogeneousnano-grainedmetalsDislocationmotion:suppressedGBslidingorcreep:nodirectevidenceOthermechanisms:?PlasticdeformationmechanismFullydensesamples

Cleansamples??(earlynecking)??(uniformdeformation)Hierarchical(heterogeneous)nanostructuresNano-twinnedGradientnano-grainedHierarchicalnanostructuredmaterialsNano-twinned&m-grainedStraindelocalization&strain-hardeningGBGrain1Grain2dGBGrain1Grain2GBstrengtheningK.Lu,L.Lu,S.Suresh,TBACBABBABCATwinMatrixCCCTBMatrixMatrixlTwinTBNano-scaleTBstrengtheningResistingdislocationtrans.

Capabilityofaccomm.disl.DislocationmobileatTB

Lowenergy—highstabilityResistingdislocationtrans.

Limitedcapabilityofaccomm.disl.DislocationimmobileatGBsHighenergy—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)100nm200nm2nmtwinboundary(111)Plan-viewTEMimages:edge-onTBsPolycrystallineCuwithnano-scaletwinsGrowthSynthesis:pulsedelectrodeposition(PED)IncreasingtwindensityTensilepropertiesofPEDnano-twinnedCuStrengthANDductilityincreasehand-in-hand!Lu,etal,Science,(2004)16mm

OriginalAC~6x10-3s-1Dislocation-TBinteraction:3modesDislocationslip-transferThreadingdislocationsTwinningpartialsT.Zhu&HJGao,ScriptaMater.,2012Hard-IHard-IISoftSlipsystems:twinnedFCCmetalsTBMatrixMatrixlTwinTBTBMatrixMatrixlTwinTBTBMatrixMatrixlTwinTBGBd_BCd_ACd_ABg_ABb_ACa_BCg_DBg_DAb_DCb_DAa_DCa_DB121110987654321HardIHardIISoftDislocationslip-transferThreadingdislocationsTwinningpartialsZ.S.Youetal,ActaMater.,2013Columnargrainswithnano-twinsinCu2mmGDDCelectrodeposition

GDLevels(m.u.d.)123450.841.532.222.923.614.304.995.68min=0.17max=6.12Strong{111}out-of-planetexture200nmGDL.Luetal,ActaMater.,2011Twinthicknesseffectsinnt-CuHall-PetchmodelTBMatrixMatrixlTwinTBConfinedlayerslipTBMatrixMatrixlTwinTBL.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:ntCuLu,etal,Science,(2009)TBMatrixMatrixlTwinTBGB5nm--Dominatedbytwinningpartials--GB/TBintersections:nucleationsitesHard-IandHard-IITB-latticedislocationinteractionsSoftTwinningpartialsnucleation&slipNano-twinnedCu:MaximumstrengthTBMatrixMatrixlTwinTBL.Lu,etal,Science,(2009)TBMatrixMatrixlTwinTBGBHJ.Gao,etal,Nature,(2010)100nm5nmb2nmTSFSFSFSFSFSFTB500nmNano-twinnedCu:ultrahighwork-hardeningL.Lu,etal,Science,(2009)Deformedcg-metals:1014~1015m-2

r~5x1016m-2

cg-Cu:n=0.35GBStrengtheningStrainhardeningCoeff.Elongation-to-failure(%)Dorl(nm)TBStrengtheningNano-twinnedCuvsnano-grainedCuK.Lu,L.Lu,S.Suresh,Science,(2009)Nano-grainedHighstrengthBrittleReducedwork-hardeningPoorstabilityNano-twinnedHighstrengthDuctileEnhancedwork-hardening

Highstability@RT,LNTStrainrate:102~103s-1Strainofeachimpact:~0.1AnvilHammerSampleLiquidnitrogen

ε=ln(Lo/Lf)0.41.11.40W.S.Zhao,etalScriptaMater.(2006)Y.S.Li,etal,ActaMater.(2008)Dynamicplasticdeformation(DPD)Bulksamples:Nano-scaledeformationtwins1

mLoadingdirectionDPDCu:nano-sizedgrains&nano-scaletwinsCross-sectionalTEMe=2.1Y.S.Li,etal,ActaMater.(2008)T/MlamellaeNano-grainsVolume%35%65%AveragesizelT/M=49nmdT=76nmSlipSlip+TwinningTwinningIIIIIIDeformationmap:CualloysZener-HollomonparameterlnZ=ln

+Q/RTY.Zhang,etal,(2011)Twinnucleussize:100nmT/Mlamellarspacing~15nmDPDCuAl4.5wt.%(ε=1.47)IncreasingTBdensity4.5l~50nml~15nmStrength&toughness:increasehand-in-handHierarchicalnanostructuredmetalsDislocation-TBinteractionsDislocationslipinT/MlamellaeDislocationnucleationatTB/GBjunctionsPlasticdeformationmechanismNano-twinnedmaterialsNano-twinnedHighstrengthDuctility&work-hardeningToughnessHighelectricalconductivityEnhancede-migrationresistance…RTNano-twinnedCualloys:strong&conductiveAgCuOFHCCuCold-workedCuAlCu-Cr-XCu-Fe-XCu-Ni-Si-XCu-Zn/Al/Sn-XCu-ZrCu-Be-XCu-Ag-XBulknt-Cu?★Thinfoilnt-CuIITBINano-twins:suppressdiffusionatGBsinCuNTsslowdowngrain-boundaryandsurfaceelectro-migrationby

oneorderofmagnitude.Turbodiscsuperalloyswithnano-twinsNi–Co-basesuperalloyTMW?675

725oCH.Haradagroup,NIMSJapanY.Yuan,etal,Adv.Eng.Mater.(2011)Nano-twinnedGradientnano-grainedHierarchicalnanostructuredmaterialsNano-twinned&m-grainedStraindelocalization&strain-hardeningDuctilitydropsmoresignificantlythanstrengthgain400nmHardphaseHardphaseWork-hardeningrateStrainSoft-phaseHard-phasereinforced??Steels:strength-ductilitytrade-off(Bananacurve)StrainlocalizationatinterfacesWork-hardeningratesdropsharplya/gM/BP/CNano-twinnedgrains:areinforcing“phase”?Single-phasedReinforcement:strong&deformableElasticallyhomogeneousPlasticallyheterogeneousAusteniticsteelsstrengthenedbynano-twinnedaustenitic(nt-g)grainsgnt-gLuK,etal,ScriptaMater.(2012)PolycrystallinecoarsegrainsNano-twinstrengthenedausteniticsteelsgNano-twins&Nano-grainsnt-gAnvilHammerSampleStrainrate:102~103s-1Eachimpact:e~0.1Dynamicplasticdeformation(DPD)W.S.Zhao,etalScriptaMater.(2006)Y.S.Li,etal,ActaMater.(2008)RXLNano-twins&Coarsegrainsnt-ggThermalstability:DPD316Lstainlesssteels1mmNTNGLoadingYanFK,etal,ActaMater.(2012)Nano-grains:33nm/100nmNT:l=23nm

500nmNT730oC/20min1mmSRXNTSRX750oCfor45min○

Micro-grained+10%NT▽

Micro-grained+2%NT□CG(D~100mm)Nano-twinned316Lsteel:tensiletestsRule-of-mixture:NT:sy~2.0GPaHighwork-hardeningratesAusteniticFerriticMartensiticPrecipitationhardenedNano-twinstrengthenedausteniteNano-twinned316LstainlesssteelsCorrosionresistance:unchanged!Nano-twinnedausteniticsteelsEnhancedstrength-ductilitysynergyEnhancedductilityatacomparablestrengthLuK,etal,ScriptaMater.(2012)gnt-g“iso-phasecomposite”0~2mm2~6mm>6mmVerticaltoTBse=0.5%VerticaltoTBs[100]0~2mm[110]e=0.5%2~6mm[100][110]>6mm[100][110]crystalzoneaxis：[100]Distance(mm)Dislocationdensity(1013m-2)0～21.6±0.32～62.3±1.9>62.4±0.9crystalzoneaxis：[110]Distance(mm)Dislocationdensity(1013m-2)0～22.0±1.02～62.0±1.3>62.0±0.8VerticaltoTBse=0.5%Recrystallizedgrains：~1010~12m-22mmnt-ge=5.0%Nano-twinned316LausteniticsteelsNano-twinnedgrains:areinforcing“phase”!Single-phasedReinforcement:strong&deformableElasticallyhomogeneousPlasticallyheterogeneousAusteniticsteelsstrengthenedbynano-twinnedaustenitic(nt-g)grainsgnt-gLuK,etal,ScriptaMater.(2012)Nt-ggrainsmayactasa“strongphase”toreinforcesoftaustenite,resultinginabetterstrength-ductilitysynergy.Aunique“iso-phasecomposite”structurewithoutgeneratingobviousstrainlocalizationatinterfacesatlowstrains,higherwork-hardeningrates.Strainanisotropydevelopsaroundnt-ggrainsathighstrains.Propertiesandperformancetobeexplored:corrosion,fatigue,creep,thermalstability…Nano-twinnedGradientnano-grainedHierarchicalnanostructuredmaterialsNano-twinned&m-grainedStraindelocalization&strain-hardeningZ.G.Suo,etal.APL(2005)StrainlocalizationinducedfailureSuppressionofstrainlocalizationbyaductilesubstrate~10%elongationwithoutcrackTensileductilityofCufilmsonapolymersubstrateInterfacede-bondingStrainlocalizationFailureGradientnano-grainedlayeronacoarse-grainedsubstrate–anidealstructureTosuppressstrainlocalizationToeliminatedebondingGrainsizeGradientNano-grainedcoarse-grainedsubstrateLargetensileplasticstraininnano-grainedmetals?Nointerface!Surfacemechanicalgrindingtreatment(SMGT)Gradientnano-grainedsurfacelayerFangTH,etal,Science(2011)SampleGNG&deformedlayerWC/CotipapWC/CoGNGDeformedCGCGK.Lu&J.Lu,J.Mater.Sci.Tech.(1999)VacuumvSampleVibrationgeneratorv:1~10m/sNano-grained&DeformedlayerSampleSurfacemechanicalattritiontreatment(SMAT)Li,Tao&Lu,ScriptaMater.(2008)Ra≈0.2mm

SMGTTensilebarsample(Cu)Unit:mm10620R10?6?10200nm(mm)500100150GNGsurfacelayerofSMGTtensilesampleTopsurfaceNano-grainedUltrafine-grained(100~300nm)Deformedcoarse-grained10mmGNGsurfacelayerofSMGTtensilesampleSMGTsample:grainsizeandmicrohardnessUnit:GPaD~100nmGNGsurfacelayerCGDeformedCG0.702.15unit:mm0.060.09<D>:20~100nm<D>:100~300nmGNGDeformedCGCGTensilestress-straincurves:GNG/CGvsCG(top50mmthick)20mme=020mme=0CGCuSMGTCue=30%e=30%Tensilesamples:surfacemorphology10mmScanningdistanceGNG/CGe=0GNG/CGe=30%CGe=30%HeightvariationStrength-ductility:GNG/CGvsdeformedCGF4.5F6eT=0%10%33%200nm200nmTensilebarsample:Cross-sectionalTEMviewTopmostlayerTensilebarsample:Cross-sectionalview1mmF6mmBet=24%Det=127%Cet=54%5mm001101111111001101CBDTensilesample:grainsizevsstrainMechanically-drivenGBmigration(graingrowth)Softeningvshardening:asaturatedgrainsize200~300nmPlasticdeformationmechanismMechanically-drivenGBmigration(graingrowth)GBmotionGBslidingCouplingGBmotion(J.Cahn2006)–indentation[Weertman2004(Cu),Minor2004(Al)]–compression[Pan2007,Weertman2008(Ni,C