The effect of microalloying additions of Au on the natural ageing of Al–Cu .pdf

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1、Availableonlineatwww.sciencedirect.comActaMaterialia58(2010)6379–6384www.elsevier.com/locate/actamatTheeffectofmicroalloyingadditionsofAuonthenaturalageingofAl–Cua,*aabaB.Klobes,O.Balarisi,M.Liu,T.E.M.Staab,K.MaieraHelmholtzInstitutfu¨rStrahlen-undKernphysik,Nußallee14-16,D-53115Bonn,Ger

2、manybISCFraunhofer,Neunerplatz2,D-97082Wu¨rzburg,GermanyReceived14October2009;receivedinrevisedform29July2010;accepted30July2010AbstractTheinfluenceofmicroalloyingadditionsofAutothebinaryAl–Cusystemisinvestigatedutilizinghardnessmeasurements,positronannihilationspectroscopyandX-rayabsorp

3、tionspectroscopy.NoroomtemperatureageingcouldbeobservedinthecaseoftheternaryAl–Cu–Aualloy.Instead,quenched-invacanciesweretrappedbyAuatomsandthuscouldnotcatalysethedecompositionofthealloy.However,artificialageingdissolvesthecomplexesofAuandvacancies.Acomparisonbetweenexperimentalandcalcu

4、latedabsorptionspectrashowsthatAuatomsdidnotagglomeratesignificantlyduringeithernaturalorartificialageing.Ó2010ActaMaterialiaInc.PublishedbyElsevierLtd.Allrightsreserved.Keywords:Aluminiumalloys;Al–Cu–Au;Ageing;Positronannihilation;XANES1.Introductionatomsbutalsoaconsiderablefractionofthe

5、rmalvacanciesboundtoasubstitutionalalloyingatom.AfterwardstheAluminiumalloyscombinehighstrengthandlightalloyevolves–dependingonthespecificageingconditionsweightandarethusofutmostimportanceasstructural(timeandtemperature)–towardstheequilibriumphasehmaterials.Inparticular,heat-treatableAla

6、lloys,whichviathevacancy-driventransportofsoluteatoms.Duringarehardenedbytheformationofsoluteagglomerates,naturalageing,i.e.storageatroomtemperature(RT)afterareusedintheautomotiveandaviationindustriesexten-quenching,Al–Cualloysarestrengthenedbytheagglomer-sively.Amongtheseprecipitationh

7、ardeningalloysanationofCuatomsonthe{100}planesoftheAlmatrix,importantclass,theso-called2xxxseries,isbasedonthenamelytheformationofGPIandGPIIzones.However,binaryAl–Cualloy.Thedecompositionsequenceofthistheadditionoffurtheralloyingelementshasagreatimpactsystemhasbeenthesubjectofa