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1、HeatTransportacrossDissimilarMaterialsNitinChandraShuklaDissertationsubmittedtothefacultyoftheVirginiaPolytechnicInstituteandStateUniversityinpartialfulfillmentoftherequirementsforthedegreeofDoctorofPhilosophyInMechanicalEngineeringProfessorScottT.Huxtabl
2、e,CommitteeChairProfessorThomasE.DillerProfessorKathleenMeehanProfessorGitiKhodaparastProfessorMarkR.PaulMay13,2009Blacksburg,VAKeywords:Nanoscaleheattransport,thermalconductivity,interfacethermalconductance,nanocomposite,metallicglass,time-domainthermore
3、flectanceCopyright(2009)HeatTransportacrossDissimilarMaterialsNitinChandraShuklaAbstractAllinterfacesofferresistancetoheattransport.Asthesizeofadeviceorstructureapproachesnanometerlengthscales,thecontributionoftheinterfacethermalresistanceoftenbecomescomp
4、arabletotheintrinsicthermalresistanceofferedbythedeviceorstructureitself.Inmanymicroelectronicdevices,heathastotransferacrossametal-nonmetalinterface,andabetterunderstandingabouttheoriginsofthisinterfacethermalconductance(inverseoftheinterfacethermalresis
5、tance)iscriticalinimprovingtheperformanceofthesedevices.Inthisdissertation,heattransportacrossdifferentmetal-nonmetalinterfacesareinvestigatedwiththeprimarygoalofgainingqualitativeandquantitativeinsightintotheheattransportmechanismsacrosssuchinterfaces.At
6、ime-domainthermoreflectance(TDTR)systemisusedtomeasurethethermalpropertiesatthenanoscale.TDTRisanopticalpump-probetechnique,anditiscapableofmeasuringthermalconductivity,k,andinterfacethermalconductance,G,simultaneously.ThefirststudyexamineskandGforamorpho
7、usandcrystallineZr47Cu31Al13Ni9metallicalloysthatareincontactwithpoly-crystallineY2O3.Themotivationbehindthisstudyistodeterminetherelativeimportanceofenergycouplingmechanismssuchaselectron-phononorphonon-phononcouplingacrosstheinterfacebychangingthemateri
8、alstructure(fromamorphoustocrystalline),butnotthecomposition.Fromthe-1-1TDTRmeasurementsk=4.5WmKfortheamorphousmetallicglassof-1-1Zr47Cu31Al13Ni9,andk=5.0WmKforthecrystallineZr47Cu31Al13Ni9.TDTRalso-2-1-2-1givesG=23