Phase-separation-in-metallic-glasses

PhaseseparationinmetallicglassesD.H.Kima,⇑,W.T.Kimb,E.S.Parkc,N.Matternd,J.Eckertd,eaCenterforNon-crystallineMaterials,DepartmentofMaterialsScienceandEngineering,YonseiUniversity,134Shinchon-dong,Seodaemun-gu,Seoul120-749,RepublicofKoreabDepartmentofOpticalEngineering,CheongjuUniversity,36Naedok-dong,Cheongju360-764,RepublicofKoreacRIAM,DepartmentofMaterialsScienceandEngineering,CollegeofEngineering,SeoulNationalUniversity,Seoul151-744,RepublicofKoreadIFWDresden,InstituteforComplexMaterials,P.O.Box270116,D-01171Dresden,GermanyeTUDresden,InstituteofMaterialsScience,D-01062Dresden,GermanyarticleinfoArticlehistory:Availableonline11May2013abstractPhaseseparationphenomenainmetallicglasssystemsarereviewed.First,abriefintroductiontotheenhancedglassformingabilityandthephaseseparationinmetallicglasssystemsisgiven.Nano-scalephaseseparationobservedinfrozen-inglassisdis-cussedinmarginalglassformerssuchasPd-,Fe,Al-basemetallicglasssystemsaswellasinbulkglassformersinCu-,Zr-andMg-basemetallicglasssystems.Sinceretentionofglassformingabilityisessentialinphaseseparatingglasses,thermodynamicandkineticconditionsforenhancedglassformingabilityisintroduced.Severalthermodynamicaspectsfordecompositionbyliquid–liquidphaseseparationwhichincludestabilityconditions,decompositioninthemulticomponentsystem,typesofmiscibilitygap,calculationofbimodalandspinodalcurvesareintroducedasabackgroundfordesignofmetallicglassesphaseseparatingintheliquidstate.Themainmechanismsforphaseseparationarenucleationandgrowthmechanismandspinodaldecompositionmechanism.Themetallicglasssystemswhichincludeanatompairwithlargeposi-tiveenthalpyofmixingdecomposebyliquid–liquidphasesepara-tionseparateintheliquidstate,formingtwotypicaltypesofmicrostructure:dropletorinterconnectedtypemicrostructuresdependingonthemechanismofphaseseparation.Bycalculationofthetileline,itispossibletodesignphaseseparatingmetallicglasseswithhighglassformingability.Eventually,bulk-typephaseseparatingmetallicglasseswithmmscalecanbesynthesized.Moreover,ifthereisagroupofthreeatomswithlargepositive0079-6425/$-seefrontmatter2013ElsevierLtd.Allrightsreserved.⇑Correspondingauthor.Tel.:[phone];fax:[phone].E-mailaddress:[e-mail](D.H.Kim).ProgressinMaterialsScience58(2013)1103–1172ContentslistsavailableatSciVerseScienceDirectProgressinMaterialsSciencejournalhomepage:fieldionmicroscopyBMGbulkmetallicglassAPTatomprobetomographyBFTEMimagebrightfieldTEMimageCSROchemicalshortrangeordering3DAP3-dimensionalatomprobeDeffeffectivediffusivityDSCdifferentialscanningcalorimetryDFTEMimagedarkfieldTEMimageEDXenergydispersiveX-rayanalysisEXAFSextendedX-rayabsorptionfinestructurefccfacecenteredcubicFEMfluctuationelectronmicroscopyGGibbsfreeenergyG0imolarGibbsfreeenergyofpurecomponentiGijthesecondderivativeofGwithrespecttoniandnjGmmolarGibbsfreeenergyGFAglassformingabilityhPlanck’sconstantsIvsteadystatehomogeneousnucleationrateperunitvolumeISROicosahedralshortrangeorderkBoltzmann’sconstantMmagnetization,A/mMROmedium-rangeorderninumberofmoloficomponentNaAvogadro’snumberNonumberofpotentialnucleationsitesperunitvolumeQactivationfreeenergyfortransportinganatomacrossthesolid–liquidinterfaceRgasconstantRErareearthelementSADPselectedareadiffractionpatternSAXSsmallangleX-rayscatteringSANSsmallangleneutronscatteringSROshortrangeorderTxtimerequiredtocrystallizeadetectablevolumeTabsolutetemperatureTccriticaltemperatureTgglasstransitiontemperatureTlliquidustemperatureTmmeltingtemperatureTrg=Tg/TmreducedglasstransitiontemperatureTwwettingtransitiontemperatureTotemperatureatwhichthecrystalandtheliquidareinequilibriumTEMtransmissionelectronmicroscopyTMtransitionalmetalelementTMAthermomechanicalanalyzerTSROtopologicalshortrangeorderingVgrowthvelocityofthecrystallinephasenucleatedfromthehighlyundercooledliquidWAXSwideangleX-rayscatteringXimolefractionoficomponent1104D.H.Kimetal./ProgressinMaterialsScience58(2013)1103–1172enthalpyofmixingintheliquidstateinthemulticomponentsys-tem,occurrenceofthreephaseseparationintheliquidstateispos-sible.Thereareseveralparametersaffectingthemicrostructureevolutionduringphaseseparation,whichincludesglasstransitionandcriticaltemperatures,shapeofbimodalandspinodalcurvesandquenchingconditions.Phaseseparationinthesolidstateofthefrozen-inglassescangiveaclueonthephaseseparationpriortocrystallizationordirectnanocrystallizationfromtheamorphousmatrix.Theamplitudeofthecompositionfluctuationwithafixedwavelengthcangrowbyheatinginthesolidstate,ifthespinodaldecomposition.Finally,someadvantagesofphaseseparationphe-nomenainmetallicglasssystemsarehighlighted.2013ElsevierLtd.Allrightsreserved.Contents1.Introduction.......................................................................11061.1.Phaseseparationinoxideglasses................................................11061.2.MetallicglasseswithenhancedGFA.............................................11061.3.Phasesepara