bulk metallic glass a new engineering material

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1、MetallurgybeyondFeBulkMetallicGlass:ANewEngineeringMaterialIsabellaGallinoandRalfBuschDept.ofMaterialsScienceandEngineeringSaarbrücken,GermanyTheOriginoftheelementsheavierthanFeTorinoSeptember24-27,2008AbundanceofelementsonEarthEvenifveryabundant,AlandSiwerediscoveredonlyinin1825Stabilityofmetalo

2、xidesDGo,standardfreeenergyofformationofonemoleofoxideStabilityofoxidesDGometalKJ/moldiscovery(300K)(year)Ag2O11Cu2O145PbO188NiO215FeO255ZnO319MgO5701755SiO28241824ZrO210271789Al2O315781825ancientM+O2=MO2EvolutionofmetalsGoldCopperBronzeIronCastIronSteelsAlloySteelsLightAlloysSuperAlloysTi-,Zr-Al

3、loysGlassyMetalsSpecialSteelsandNewsuperalloysStoneageBronzeageIronageAgeofadvancedmaterialsSteeltechnologiesThreeClassesofStructuralMaterials:Metals,Ceramics,PolymersMetals(here:crystals)Ceramics(here:amorphous)Polymers(here:crystalline+amorphous)GlassesareFrozen-LiquidsGlass(amorphous)Crystall

4、ineTheviscosityincreaseswithundercoolinguntiltheliquidfreezestoaglassCriticalcoolingratesandthicknessesfordifferentmaterials‚conventional‘metallicglass‚bulk‘metallicglassPolymersOxideglass(ceramics)CriticalcoolingrateK/sMax.thicknessTTTdiagrams“Conventional”metallicglasses(1959-1984)a)AuSiNbNiZr

5、Cucriticalcoolingrates:105-106K/sFeBetc…..Bulkmetallicglassesb)Ni-Pd-P[Turnbull,Drehman,Greer(1984)]La-Al-Ni[Inoueandco-workers(1991)]Mg-Cu-YZr-Al-Ni-Cucriticalcoolingrate:100K/setc…..c)Zr-Ti-Cu-Ni-Be[Johnsonandcoworkers(1993)]Zr-Ti-Al-Cu-Nicriticalcoolingrate:1K/setc……from:W.L.Johnson,MaterialsR

6、esearchSocietyBulletin,October1999BulkmetallicglassformingliquidsMulticomponenteutecticalloyswithstrongnegativeheatofmixingP.Haasen,PhysicalMetallurgy3rdedTangetal.,Nature402,160(1999)Largesizemismatchbetweenthecomponents(destabilizationofthecrystallinephases)Zr41.2Ti13.8Cu12.5Ni10Be22.5Glassform

7、ingabilityThermodynamicsandkineticsdeterminenucleationandgrowthofcrystals→TimeTemperatureTransformation(TTT)diagramsR.Busch,JOM52(7),39(2000)NucleationrateI(T)=A∙T∙D∙exp(DG*/RT)with:D1/hr*2s/DGDG*=(16ps3/3DG2)f(θ)s:i