铝腐蚀金相图谱

MetallographicEtchingofAluminumandItsAlloysGeorgeF.VanderVoortBuehlerLtd.LakeBluff,IllinoisUSAAndElenaP.ManilovaPolzunovInstituteSt.Petersburg,RussiaPreparationofAluminumSpecimens•Grindwith240-gritSiCwater-cooledpaper,240rpm,5lbs.(20N)perspecimen,untilco-planar•Polishwith9-µmDiamondonanUltra-Pol(silk)cloth,150rpm,5lbs/specimen,5minutes(contrarotation)•Polishwith3-µmDiamondonaTridentcloth,150rpm,5lbs/specimen,4minutes(contrarotation)•Polishwith1-µmDiamondonaTridentcloth,150rpm,5lbs/specimen,3minutes(contrarotation)•Polishwith0.05-µmColloidalSilicaonaMicroclothpad,120rpm,5lbs/specimen,3minutes(contrarotation)(Contra:Headandplatenrotateinoppositedirections)Standard“Black&White”EtchantsforAluminum•Keller’sReagent95mLwater,2.5mLHNO3,1.5mLHCl,1.0mLHF–Immerse•CausticSodiumFluorideEtch93mLwater,2gNaOH,5gNaF•Graff-SargentEtch84mLwater,15.5mLHNO3,0.5mLHF,3gCrO3AnodizingwithBarker’sReagent1.8%Fluoboricacidinwater20-45Vdc,forupto2minutesExaminewithcrossedpolarizedlight,plusasensitivetint(firstorderredplate,orλplate)toseethemicrostructureincolor.Itisgoodforgrainsize,butdoesnotrevealalloysegregation.ExamplesofAnodizingwithBarker’sReagentItdoesnotrevealalloysegregationincastalloysbutdoesdisplaythedendriteswell.ItiswidelyapplicableforrevealinggrainstructureinwroughtalloysBut,youmusthaveaconductivepath.BrightFieldPolarizedLight100µm100µmPL+SensitiveTintGrainstructureofwrought1100gradefoilafterelectrolyticpolishingandanodizingwithBarker’sreagent(20Vdc,2min),andviewedwithbrightfield(top),polarizedlight(left)andwithpolarizedlightplusasensitivetintfilter(right).NotethatcolorisnotobservedinbrightfieldbecauseaninterferencefilmisnotformedusingBarker’sreagent.As-cast(concast)1100Al(99%Al)anodizedwithBarker’sreagent(30Vdc,2min.)revealedadendriticsolidificationstructure.Notethatnoevidenceofsegregationisapparent.Originalat50X.Viewedwithcrossedpolars+sensitivetint.Wrought2024-Faluminum(Al–4.4%Cu–1.5%Mg–0.6%Mn)bar(28.5mmdiam.)showingthegrainstructureandintermetallics.Magnificationbaris200µmlong.AnodizedwithBarker’sreagent(30Vdc,2min.).Transverseplane.Wrought5754-Faluminumstrip(Al–3.2%Mg–0.4%Mn+Cr)anodizedwithBarker’sreagent(30Vdc,2min.).Thestripwascoldworkedandannealedat343°C(650°F)for2h.Thegrainstructureisfullyrecrystallized.Wrought6005aluminum(Al–0.5%Mg–0.8%Si)anodizedwithBarker’sreagent(20Vdc,2min.)revealinganequiaxedalphagrainstructure.Originalat50X.Viewedwithcrossedpolarizedlightplussensitivetint.Shearedendof6061-F(Al–1%Mg–0.6%Si–0.2%Cr–0.27%Cu)extrudedrodanodizedwithBarker’sreagent(30Vdc,2min.)revealingtheheavilyelongatedgrainsfromextrudingandthecompressionoftheshearedend.Magnificationbaris100µmlong.Wrought7075-T74aluminum(Al–1.6%Cu–2.5%Mg–5.6%Zn–0.23%Cr)anodizedwithBarker’sreagent(20Vdc,2min.)showinghighlyelongated,recrystallizedsurfacegrainsonafinegrainedinteriorstructure.Magnificationbaris50µmlong.Viewedwithcrossedpolarizedlightplussensitivetint.Color“TintEtching”WithWeck’sReagent100mLwater4gKMnO41gNaOHUseatroomtemperatureImmerseupto20s,orlonger,untilsurfaceiscoloredExamplesoftheUseofWeck’sReagentEasiertoobtaingoodresultswithcastingscomparedtowroughtgrades.Easytomixanduse,notparticularlydangerous.Revealssegregationverywell.GrainstructurecanberevealedwithmostwroughtcompositionsAs-cast(concast)3004aluminum(Al–1.25%Mn–1.05%Mg)tintetchedwithWeck’sreagentandviewedwithcrossedpolarsplussensitivetint.Magnificationbaris50µmlong.Revealssegregation(“coring”)withinthedendritesandintermetallicsbetweenthedendrites.As-cast206aluminum(Al–4.4%Cu–0.3%Mg–0.3%Mn)tintetchedwithWeck’sreagentandviewedwithcrossedpolars+sensitivetint.Magnificationbaris50µmlong.As-cast319aluminum(Al–6.0%Si–3.5%Cu)tintetchedwithWeck’sreagentandviewedwithcrossedpolarizedlight.Magnificationbaris100µmlong.As-cast319aluminum(Al–6.0%Si–3.5%Cu)tintetchedwithWeck’sreagentandviewedwithcrossedpolarizedlight.Magnificationbaris100µmlong.As-cast(concast)1100Al(99%Al)tintetchedwithWeck’sreagentrevealingadendriticsolidificationstructure.Notethatthesegregationisrevealedvividly.Magnificationbaris200µmlong.Viewedwithcrossedpolars+sensitivetint.CastA356AluminumLargePermanentMoldCasting,200XSmallPermanentMoldCasting,200XDendriticstructureandeutecticstructureofA356permanentmoldcastingsrevealedusingWeck’sreagent(polarizedlightplussensitivetint,200X)CastA356AluminumThixocast,200XThixocastandThixoformedMicrostructureofA356madebythixocastingandbythixocastingandthixoformingrevealedusingWeck’sreagent(viewedwithpolarizedlightandsensitivetint,200X).CastA356–VRC/PRCCaststructureofVRC/PRCcastA356aluminumrevealedusingWeck’sreagent(polarizedlightplussensitivetint,200X)MicrostructureofanSSMbilletofA357aluminumetchedwithWeck’sandviewedinbrightfield(200x).Dendritesofα-Alandaeutecticofα-AlandSiinas-castAl–7.12%SietchedwithWeck’s,polarizedlightplussensitivetint.Near-eutecticmicrostructureofas-castAl–11.7%SialloyetchedwithWeck’sandviewedwithpolarizedlightplussensitivetint.Hypereutecticas-castAl–19.85%SiwithproeutecticSiandaeutecticofα-AlandSietchedwithWeck’sandviewedwithpolarizedlightplussensitivetint.As-C