Cu-Cr合金定向凝固組織演化研究.pdf

1、西北工業(yè)大學碩士學位論文CuCr合金定向凝固組織演化研究姓名：李曉歷申請學位級別：碩士專業(yè)：材料加工工程指導(dǎo)教師：李金山胡銳20060801ABSTRACTABSTRACTHighconductivityandhigllstrengthCubasedalloysmanufacturedastheintegratedcircuitlendframeandtrolleywirematerials黜appliedextensivelyinIT

2、andfailroadindustryTodate，mostresearchesoilhi曲strengthandhighconductivityCuCralloysarcfocusedontheagingandheattreatmentprocessestocon仃olmicrostructuresincludingthesize，magnitudeandthematchrelationshipbetweendifferentphas

3、esThesolidificationprocess，averyimportantmanufacturingprocessisoftenneglectedandreceivedlessconsiderationInthispapermicrostrucmreevolutionsandcharacteristicsofCuO5％CrandCu1O％Cralloysarcrespectivelyinvestigatedunderdirect

4、ionalsolidification11嵋mainresultsdemonstrateasfollows：Theplanarcellularcoal∞dendritic，irregularcellularandfmeplatelikesolidifiedmicrostructuresofCuO5％Cralloyarcobtainedatthepullingvelocityincreasingfrom2pra／sto500tml／swi

5、nlthetemperaturegradientof200K／cmIftheliquiddiffusioncoefficientDLiSaboutlx10“gm2／sthetheoreticalcalculanonof6jJm／sfortheplanarinterfacestableisinagreementwiththeexperimentalresultof5“m／sWhenthepullingvelocityachieves10p

6、m／sthenonequilibriumsolidifica矗oncoupledeutecticsforminthedirectionallysolidifiedmicrostructuresofCuO5％CralloyAttheSalnetime，thevolumefractionofcoupledeutecticsdecreasesasthepullingvelocityincreasesn倫primarydendritica胍sp

7、acingofCuO5％CrisinbetweenthecalculationresultsofKFmodelandHuntLumodelunderdirectionalsolidificationDirectionallysolidifiedmicrostructuresandsolutedistributionofCuO5％CralloyinaninitialtransientzoneisdiscussedItshowsthatth

8、eplanarinterfacemaybeunstableintheinitialtransientzoneatthepullingvelocityabovethecriticalvaluenleequationforthecriticalvaluehasbeendeducedintheinitialtransientzoneThebandedmicrostructuresOccurinthedirectionalsolidifiedC

9、u1O％Crhypoeutecticalloyatthepullingvelocityrangingfrom220、mlSOneofbandedmicrostructureisthesinglephaseplanarinterface、ⅣitllcoupledgrowtheutecticsAnotherbandedmicrostructureisthesinglephaseplanarinterfacewitllcellularsttl

10、lctureSplnscoupledeutecticsgrowthinbetweenThebandedmicrostructureCan’tformatthesteadystatesolidificationprocessandthesolidificationvelocityisalwayschangingasfunctionsofthesolutediffusionlengthandsolutedistributionaheadof