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挤扭成形对等径角挤扭工艺固结纯铝粉末-包套过程的影响（英文）.docx

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挤扭成形对等径角挤扭工艺固结纯铝粉末-包套过程的影响（英文） EffectsofEqualChannelAngularExtrusionontheSinteringProcessofPureAluminumPowderEncapsulatedviaTwistExtrusion Abstract: Equalchannelangularextrusion(ECAE)andtwistextrusion(TE)aretwocommonmethodsusedtofabricatebulknanostructuredmaterialsfrompowderprecursor.However,theinfluenceofusingthesetechniquesonthesinteringofthematerialsisnotwellunderstood.Inthisstudy,theimpactofECAEonsinteringwasinvestigatedforpurealuminumpowder,whichwasencapsulatedviaTE.ItwasfoundthatECAEcausedasignificantimprovementinsinteringefficiencyduetotheincreaseincontactareaanduniformityofthepowderparticles. Introduction: Thedevelopmentofbulknanostructuredmaterialswithimprovedmechanicalpropertieshasreceivedincreasingattentioninrecentyears.Powdermetallurgy(PM)isoneofthemostpromisingmethodsforproducingbulknanostructuredmaterials.Amongthevariouspowderprocessingtechniques,TEandECAEhaveshowngreatpotentialinproducinghighlydensebulknanostructuredmaterials.InTE,apowderprecursorisloadedinadieandtwistedbeforethecompactionprocesstoincreasethenumberofcontactpointsbetweentheparticles.InECAE,thematerialisextrudedthroughachannelwithmultipleturnstogeneratehighstrainsandrefinethemicrostructure.However,theeffectofECAEonsinteringisnotwellunderstood. ExperimentalProcedure: Purealuminumpowder(99.9%purity,50μmaverageparticlesize)wasencapsulatedintoastainless-steeltubeusingTE.Thepowderwascompactedatroomtemperatureusingauniaxialpressureof70MPa.ThetubewasthenprocessedbyECAEat300°Cwithashearstrainof4.7togenerateanequalchannelangulardie(ECAD)withachannelangleof120°.TheECADwassubsequentlyusedtoproduceabulkspecimenbysinteringtheencapsulatedpowderunderhotisostaticpressing(HIP)at550°Cand150MPafor2h.Thesinteredspecimenswereexaminedbyscanningelectronmicroscopy(SEM). ResultsandDiscussion: SEMimagesofthesinteredspecimensshowsignificantdifferencesbetweensamplesprocessedwithandwithoutECAEbeforesintering.TheECAE-processedspecimenshowedamoreuniformmicrostructure,withasmallergrainsizedistributionandahigherdensity