γtial基金属间化合物电磁成形定向凝固及组织特性研究

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1、西北工业大学硕士学位论文ABSTRACTThepurposeofthispaperistodescribeandanalyzefirstlytheprocessingofcontactlesselectromagneticshapingof-f-basedTiAlintermetallic.Directionalsolidificationcharacteristicsofsuccessfullyshapedy-TiAlalloysisthenpresentedandinvestigatedinrelationwiththeexperimentalpara

2、meters.To面this,directionalsolidificationexperimentswithoutpolutionofy-TiAlalloysweremadeontheexperimentalapparatusdesignedbyourselvesthroughElectromagneticConfinement&DirectionalSolidificationprocessingusingaselectedTi-48A1alloyasresearchobject,Detailedissuesincludetwomainaspectsa

3、sfolows:1.Exploringcontantlessprocessofdirectionalsolidificationmicrostructurepreparationof-1-basedTiAlintermetallicbystabilizedelectromagneticshaping.Basedontheachievementofcontantlesssolidificationprocedureofstainlesssteelsamples,theshapingsystemcomposedofinductorandscreenfory-T

4、iAlalloysisestablishedandoptimumtemperaturegradientandsolidificationratesaretookintoaccount.Thus,onthefoundationofstableshapingofy-TiAImetallicmolteninelectromagneticconfinement,directionalsolidificationofTi-48A1(at%)sampleswithoutpollutionisobtainedbyusingtheprotocoldescribedabov

5、ed.2.Identi尔ngsolidificationcharacteristicsofy-TiAlalloysundertheconditionsofsub-rapiddirectionalsolidification.Usingmodifieddirectionalsolidificationprocessingwithmol氏theinfluenceofexperimentalparameterssuchassolidificationratesoncompetitionandchoiceofstableandmetastablephaseandt

6、hegrowingmorphologiesofsolidificationinterfaceandsoonisdiscussed.Besides,influencemechanismisanalyzedsubsequently,anddesiredprocessingparametersforcontrollingcrystalstructureareprovided.Inconclusion,妙meansoftheabovestudiesweareexpectedtoachievedesiredshapeswithcleanishsurfaceanddi

7、rectionalsolidificationmicrostructureofy-TiAlalloyswithcircularsection.Solidificationregulationsandtheirmechanismsofperitecticy-TiAIaloysareclarifiedbasically.Itisfoundthatowingtolowdensity,moltenRAIaloysarepronetobedrivenbyintenseelectromagneticstirringduringEMCprocess,yetbycontr

8、ollingtheprocessingparametersprop