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1、------------------------------------------------------------------------------------------------_英文_行波磁场对定向凝固Pb_Sn合金枝晶生长的影响_MINZhi-xian,SHENJun,WANGLing-shui,LIULinStateKeyLaboratoryofSolidificationProcessing,NorthwesternPolytechnicalUniversity,Xi’an710072,ChinaReceived28Septemb
2、er2010;accepted24June2011EffectoftravelingmagneticfieldondendritegrowthofPb-SnalloyduringdirectionalsolidificationAbstract:Theinfluenceofmeltconvectionondendritegrowthduringtheupward-directionalsolidificationofPb-33%Snbinaryalloyswasinvestigated.Themeltconvectionwasmodulatedbytr
3、avelingmagneticfield.Whenthedirectionoftravelingmagneticfieldwaschangedfromupwardtodownward,theprimarydendritespacinggraduallyincreased,andthedistributionpeakoftheprimarydendritespacingshiftedtothefieldofnarrowerspacing.Theseresultfromthedifferentintensitiesofmeltconvection,whic
4、harecontrolledbythetravelingmagneticfield.Theeffectsofthetravelingmagneticfieldonmeltconvectionaresimilartothoseofadjustmentinthegravitylevel,thus,theprimarydendritespacingvaries.Whentheintensityofthetravelingmagneticfieldwas1mT,andthedrawingspeedwas50μm/s,thegravityacceleration
5、reached0.22gforthedownward-travelingmagneticfieldand3.07gfortheupward-travelingmagneticfield.Keywords:directionalsolidification;microstructure;Pb-Snalloy;——————————————————————————————————————---------------------------------------------------------------------------------------
6、---------travelingmagneticfield1IntroductionDendritesarethemostcommonpatternsduringdirectionalsolidification.Dendriteformationincludesmanycharacteristicpropertiesandlengths,suchasprimarydendritespacing,secondarydendritespacing,anddendritetipradius.Inordertodescribetheselengths,d
7、etailedtheoreticalmodelswereestablishedunderdiffusiveconditions[1].Inmostexperimentalstudies,however,theconvectioneffectsplayanimportantroleinterrestrialconditions,thuscausingconflictsbetweenthetheoreticalpredictionsandexperimentalresults.Recentstudiesshowedthatconvectionhassign
8、ificanteffectsondendritespacing[2?3].Manymethod
