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时间:2019-07-11
《Aluminium alloys for demanding applications_2010 Hagen Symposium Reports》由会员上传分享,免费在线阅读,更多相关内容在学术论文-天天文库。
1、2010HagenSymposiumReports:Aluminiumalloysfordemandingapplications12thJan,2011Inthisarticle,thefifthofourreportsfromthe2010HagenSymposium,Germany,DrGeorgSchlieperhighlightsapresentationbyKlausHummertofPLMPowderLightMetalsGmbHinGladbeck,Germany.HummertdiscusseshowPowderMetallurgy(PM
2、)hasfoundroutestoproducespecialaluminiumalloyswithexceptionallyhighstrengthatelevatedtemperatures,highwearresistanceandahighmodulusofelasticity.Aluminiumanditsalloysarewidelyusedmaterials.Aluminiumisreadilyavailableinlargequantities,hasalowspecificweight,excellentelectricalconduct
3、ivity,anattractivesurfaceappearanceandhighcorrosionresistance.Itslimitationsarewhereahighstrengthandstiffness,i.e.ahighmodulusofelasticity,isrequiredandwhereelevatedtemperaturesprevail.Fig.1Tensilestrengthversustemperatureofaluminiumalloys(courtesyPLM)Thelimitsofaluminiumalloyspro
4、ducedbyingotmetallurgy(IM)aregivenbythelowercurveinFig.1.ThemostadvancedAlZnMgCualloysachieveastrengthlevelatroomtemperature(RT)ofupto600MPa.Attemperaturesabove100°CthestrengthbeginstodropdrasticallyandIMalloysarehardlysuitablefortechnicalapplicationsabove200°Cbecausetheylosetoomu
5、chstrength.HighperformancePMaluminiumalloyscanextendtherangeofapplicationtotheuppercurveinFig.1.Twometallurgicalconceptsareemployedforspecialaluminiumalloyswithhighstrengthandwearresistance;precipitationhardeninganddispersionstrengthening.PrecipitationhardeningispossiblebothinIMan
6、dPMalloys,butPMcanapplyhighercoolingratesbecausetheheatcanbeextractedfromasmallpowderparticlemuchfasterthanfromalargervolume.Theresultsaremuchfinerprecipitatesinthepowderoreventhesuppressionofprecipitationinthefirststepandabettercontroloftheamountandstructureofprecipitatesaftercon
7、solidationandheattreatment.Fig.2Processingstepsforhighperformancealuminium(courtesyPLM)Whileprecipitationhardeningimpliesthatthesecondphaseprovidingthehardeningeffectissolubleinthemelt,completelyinsolublephasescanbeintroducedinthematerialbymechanicalalloying(MA).Reactionmilling(RM
8、)isasimilarprocesswhereachemicalr
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