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Influence_1Influe

    Influence

162

    ;Vo1.5No.3

    ;?-?…Ill?JJ?ntIUenCeottitan-UmContentonwear

    ;resistanceofelectrolyticlow-titanium

    ;eutecticAI-Sipistonalloys

    ;WangJiefang’,XieJingpei,YanShuqing,LiuZhongxia’,WengYonggang’,

    ;WangMingxing’,SongTianfu’

    ;fJ.TheKeyLaboratoryofMaterialPhysics,MinistryofEducation,ZhengzhouUniversity,Zhengzhou450052,Henan,China;

    ;2.HenanUniversityofScienceandTechnology,Luoyang,Henan,China) ;Abstract:ThewearresistanceofsixkindsoftheelectrolyticIowtitaniumeutecticAISi

    pistonalloyswithvarious

    ;Ticontentrangingfrom0.00wt.%to0.21wt.%hasbeenstudied.AnewmethodofaddingTiisadoptedinthe

    ;electrolyticIow-titaniumaIuminumalloyingots.TheelectrolyticIowtitaniumeutectic

    AISipistonalloysareproduced

    ;byremeltingtheelectrolyticIow.titaniumaIuminumalloy,crystafsilicon.puremagnesium,AI50%CuandAI10%Mn

    ;masteralloy.ThewearexperimentsareconductedusingMM200weartestingmachineunderIubricetingcondition.

    ;TheresultsindicatethatthebetterwearresistanceandtheIessweightIOSSareachievedinthestudyforthe

    ;eutecticAISipistonalloyswith0.08vvt.%0.12wt.%Ticontent.Thehighestultimatet

    ensilestrengthof135.94MPa

    ;at300.CandHV141.70hardnessofthealloysareobtainedat0.12wt.%and0.08vvt.%Ticontent.respectively.The

    ;wearmechanismoftheeutecticAfSipistonalloysunderlubricatingconditionisabrasivewear.

    ;Keywords:electrolyticlow?-titaniumaluminumalloy;eutecticAI?-Sipistonalloy;wearresistance

    ;CLCnumber:TG146.21Documentcode:AArticleID:1672-6421f2008)0316205

    ;7L108isakindofalloyfromtheeutecticA1Sipiston

    ;ZJalloysfamily,whichhashighstrength,lowthermal

    ;expansioncoefficient,highwearresistance,excellent

    ;castabilityandlowdensity.Thesepropertiesleadtothe

    ;aDplicationofA1Sieutecticalloysintheautomotiveindustry,

    ;especiallyforpistons,cylinderblocks,connectingrodsandair

    ;conditionercompressorhousings.Previousstudieshavebeen

    ;carriedoutabouttheinfluenceofvariousalloyingelements

    ;onwearresistanceofA1Sibinaryalloys.Itwasreportedthat ;thehypereutecticalloysexperiencedahigherwearratethan ;thehypoeutecticalloysinastudyofdryslidingwearofA1

    ;Sibinaryalloysagainstasteelcounterpartsurface,where

    ”.Thewear ;adhesivewearwasapredominantprocess~1-2,

    ;resistanceofA1.SialloyswasimprovedwithincreasingofSi ;contentuptoaneareutecticcomposition.Furthermore,itwas ;indicatedthatSiadditionsimprovedseizureresistancewiththe ;optimumSicontentcorrespondingtothenear-eutecticvalue-2j. ;TheincreaseofSicontentinthealloysimprovedthewear ;resistanceandthehardnessofA1.Sialloys.Theincrease

    ;ofTicontent(upto4wt.%)intheA112wt.%Sieutecticalloys ;improvedwearresistanceofbothascastandheattreated

    ;alloys.However,thesealloysshowedhigherwearrates,thus ;Female,bornin1968,associateprofessorPh.D.Research ;interests:propertiesandapplicationofelectrolyticlow-Iqalloys. ;E?mail:wangjfrose@126.com

    ;Received:2008-03--12;Accepted:2008-06--20

    ;1owerwearresistance.comparedwiththeA1.Sibinaryalloy[41. ;Titaniumisoneofthemosteffectivegrainrefinersof ;aluminiumalloy.Theelectrolyticlowtitaniumaluminiumalloy

    ;ingotsareproducedbyaddingasmallamountofTi02into ;electrolyte,whichisonlydifferentfrompurealuminiumingots ;inTicontent[5-61.It’SanewmethodofaddingTielement.and

    ;itsessentialadvantagesarecostcheaper,technicallysimpler, ;andtheTiphasebyelectrolytemethoddistributedfiBeand ;highlydispersion,comparedwiththemethodofA1Timaster

    ;alloy[5-6].Onekindofthealloysisproducedbyremeltingpure ;aluminiumingotandSi,Cu,Mn,Mgalloyingelements,which ;iscalledZL108.Otherkindofthealloysareproducedby ;remeltingelectrolyticlowtitaniumalurniniumalloyingotand

    ;Si,Cu,Mn,Mgalloyingelements,whichiscalledZL108Tin.

    ;Theaimofthepresentworkistoinvestigatetheinfluenceof ;Ticontentonmechanicalpropertiesandwearresistanceunder ;lubricatingconditionofheattreatedeutecticA1Sipiston

    ;alloysZL108.Atthesarrletime,itconbeexpectedtoprovide ;experimenta1evidenceandtheoreticalanalysisfordirectly ;applyingtheelectrolyticlowtitaniumaluminiumalloyin

    ;automotiveindustry.

    ;1Experiment

    ;1.1Materials

    ;Rawmaterialsintheprocessincludepurealuminiumingots, ;electrolyticlowtitanium(A10.3wt.%Ti)aluminiumalloy

    ;ingots,crystalsilicon,puremagnesium,A150%Cu,A1

;

    ;August2008

    ;10%MnandA1.10%Srmasteralloy.

    ;1.2Meltingandcasting

    ,then,theyweremelted ;Al1materialswerepreheatedat200?

    ;ina7.5kWelectricalresistancefurnaceusinga12#graphite ;crucible.Themeltwasmodifiedwithstrontium(additionof ;O.04wt.%Sr)at750X2,degassedwithargongasat730~Cfor ;10min.thenpouredintoametallicmould(preheatedat200?)

    ;Element

    ;ZL108

    ;ZL10811-1

    ;ZL10811-2

    ;ZL108Ti.3

    ;ZL10811-4

    ;ZL10811.5

    ;at71O?.Thechemicalcompositionofthealloysislistedin ;Table1.rrhedimensionsofthecasttensilebarsareillustrated ;inFjg.1.Thedimensionsofthewearspecimensarecubicof ;11mitt×8mill×17.8mil1.Thecounterfaceis40Crsteeldisc ;Of50milldiameter.whosehardnessisHRC4045.TheT6

    ;heattreatmentisusedforallspecimens.i.e.,solidsolution ;treatmentfor7hat515?,quenchinginwaterof60”C,aging

    ;for16hat175?.then.air-coo32

    ;/{

    ;l?

    ;l

    ;TT?萤@I4)002lAIBI(

    ;e

    ;Fig.1Thedimensionsofthetensilespecimens

    ;1.3Experimentmethods

    ;Theultimatetensilestrength(UTS1at300?wasmeasured

    ;usingwJ10BQingshanmechanicaluniversaltestingmachine. ;Thetensilespecimenswereheatedto300?inthefurnaceand

    ;holdingfor30min.Themaximumloadis20kN.thetensile ;velocityis1mm/min.Eachkindofthealloyshas8specimens ;tested.

    ;Wearexperimentsatroomtemperaturearecarriedoutusing ;MM200weartestingmachinewithaloadof40kg.Therotating ;speedofthelowersteeldiscis400rpm.Linearvelocityis ;1.05m/s.Thespecimensarelubricatedbv2Omachineoilat

    ;thespeedof1114dropsperminute.Eachspecimeniswom ;threetimes.andeverytimelastsfor1h(runout20minfirst). ;Thewearformisthefacecontactingslidingwear.Thewear

    ;behaviorsofthealloysaredeterminedbyweightloss. ;2Resultsanddiscussion

    ;2.1MechanicaIpropertiesandHVhardness ;ofthealloys

    ;Figures2and3showtheinfluenceofTicontentontheUTS

    andHVhardnessofthealloys.respectively.The ;at300?

    ;TicontentintheeutecticAlSipistonalloysareinvestigated ;intherangefrom0.00wt.%to0.21wt.%.Theresultclearly

    ;indicatesthattheUTSat300?increasesgraduallyastheTi ;contentintheeutecticAlSipistonalloysupto0.12wt.%. ;Mn

    ;0.799

    ;0.677

    ;0.761

    ;0.577

    ;0.734

    ;0.683

    ;<0.01

    ;0.05

    ;0.08

    ;0.12

    ;0.16

    ;0.21

    ;Fe

    ;0.155

    ;0.131

    ;0.147

    ;0.120

    ;0.154

    ;0.136

    ;Sr

    ;0.O3

    ;0.03

    ;0.O3

    ;0.03

    ;0.O3

    ;0.O3

    ;Balance

    ;TicontentinAISieutecticalIoys,wt%

    ;Fig.2TheinfluenceofTicontentontheUTSat300.C ;TicontentinAI-Sieutecticalloys,wt% ;Fig.3TheinfluenceofTicontentontheHVhardness ;anddecreasesquicklywiththeTicontentabove0.16wt. ;WhentheTicontentinthealloysreaches0.21wt.%.theUTS

;at300?islessthanthatoftheeutecticAlSiZL108alloy

    ;withnoTiaddition.TheHVhardnessincreasesrapidlyas ;theTicontentincreasesupto0.05wt.%.andinsignificantly ;changingoftheHVhardnesswiththeTicontentincreasing ;from0.05wt.%to0.16wt.%,thereafter.theHVhardness ;decreasesrapidlywhentheTicontentinthealloysreaches ;0.21wt.%.

    ;163

    ;o0n协卜3??0cpJ>r

    ;

    ;—??—?CHINAFOUNDRY

    ;164

    ;2.2Wearbehaviorandwornmorphology

    ;Figure4showstherelationshipbetweentotal3hwearweight ;lOSSandTicontentoftheheattreatedeutecticA1Sipiston

    ;alloys.Figure5showstherelationshipbetweenaverageof ;weightlossperhourandTicontentoftheheat-treatedeutectic ;AlSipistonalloys.Theyrevealthatthewearresistanceofthe ;alloysatfirstincreaseswithincreasingofTicontentinthealloys ;from0.00wt.%0.12wt.%andthendecreaseswithcontinuous ;increasingofTicontentinthealloys.TheZL108Ti2and

    ;ZL108Ti3alloysshowlowerwearrate.Anoptimumamount ;ofTiintheeutecticA1SiZL108pistonalloysis0.08wt.%

    ;0.12wt.%forwearpropertiesunderthelubricatingcondition. ;TicontentinalIoys,wt%

    ;Fig.4TheinfluenceofTicontenton3hweightloss ;l5o3

    ;Ticontentinalloyswt%

    ;Fig.5TheinfluenceofTicontentonaverageofweightloss ;perhour

    ;Figure6showsSEMmicrographsofwornsurfacesofthe ;heattreatedeutecticA1SipistonalloysZL108andZL108Ti.

    ;whichexhibitingdifferentmorphologies.A1lthealloysshow ;abrasivegroovesandstripes.Figure7istheSEMmicrographs ;ofthewornsurfaceswithhighermagnification.Itcanbe ;shownthatthegroovesofthewornsurfaceoftheZL108Ti2

    ;andZL108Ti3alloysaremoreshallowanddiscontinuous ;somewhere(seeFig.7(b)and(c)),whilethegroovesand ;stripesofthewornsurfaceoftheZL108arecontinuous. ;deeperandwider(seeFig.7(a)).

    ;Fig.6WornsurfaceofeutecticAI-Sipistonalloys:noTiaddition(a);0.08wt.%Ti(b);0.12w

    t.%Ti(c)

    ;Fig.7HighermultipleSEMmicrographsofwornsurfacemorphologyofeutecticAI-Sipist

    onalloys:

    ;noTiaddition(a);0.08wt.%Ti(b);0.12wt.%Ti(c) ;2.3Wearmechanism

    ;ThemainphasesintheeutecticA1SiZL108alloysareO【一A1

    ;andeutecticSiparticles.Themicrostructuresoftheeutectic ;A1SipistonalloysZL108andZL108Ti3areshownin

    ;Fig.8.Themorphologyofdendritica(A1)ofZL108and ;ZL108Ti3alloysareshowninFig.8(a)and(b),respectively. ;ThemorphologiesoftheeutecticSiparticlesofZL108and ;ZL108Ti3alloysareshowninFig.8(c)and(d),respectively. ;TheseconddendriticarlTlspacing(DAS)inFig.8(b)issmaller ;thanthatinFig.8(a1.Thesizeandshapeoftheeutecticsilicon ;particlesissmallerandfiner,distributionoftheeutecticsilicon ;particlesismoreuniforminFig.8(d)thanthatinFig8(c). ;Someintermetalliccompoundphaseinhabitslittlevolume ;0E-Ioc-IQ??oIlcbl0^o0mL>

    ;E,??oIlcbI?;Ioc

    ;

    ;August2008

    ;fractionl2].

    ;Mg,SiandCuA1,phasesaresoluteduniformly

    treatment.Themicrohardness ;intheAlmatrixafterheat

    ;oftheoppositesteelcounterfaceisgreaterthanthatofthe ;aluminummatrix.Itgreatlyimpactsonthealuminummarx. ;Themicrohardnessoftheprotrudingeutecticsiliconphase ;isgreaterthanthatofaluminummatrix.Itcontactsdirectly ;thesteelcounterfaceandtherebyavoidingcontactbetween ;Research&Development

    ;thealuminummatrixandthesteelcounterface.Theeutectic ;siliconparticlesarenoteasytodeformplasticallytotake ;upenergyunderheavierloadduringthewearprocess.They ;mightbecomefragmentandpeelofftobecomeabrasive.The ;mainwearmechanismoftheexperimentsunderlubricating ;conditjonjsabrasivewear.

    ;Fig.8Themorphologiesofdendritic

    fAI)andtheeutecticSiparticlesoftheeutecticAISi

    ;pistonalloysZL108andZL108Ti3:ZL108(a);ZL108Ti3(b);ZL108(c);ZL108Ti3(d)

    ;Inconclusion,Tiisoneofthemosteffectivegrainrefinement ;elementsofaluminiumalloy~Butitdoesnotmean,themore ;andthebetterforTicontentinalloys.Whentheexperimental ;eutecticA1.SiZL108alloysaremadebytheelectrolyticlow

    ;titaniumA1basedalloys.higherSicontentinalloyscanmove ;theperitecticpointofTiA1phasetotheleft[13-14]. ;Sicanalso

    ;replacepartiallytheTiofTiAl3phaseandformtheternary ;compoundTi(Al1xSix)whichdecreasestheeffectof

    ;heterogeneitynucleationofTiAlparticles.WhenTicontent ;islower.itcannotrefinethemicrostructureofexperimental ;alloysevidently.WhileTicontentinexperimentalalloys ;increases,theamountoftheternarycompoundTi(AllxSix)3

    ;increases,theabilityOfheterOgeneitVnucleationenhances,

    coolingdegreeofTielementincreases ;componentunder

    ;whichcanactivatesmoreAlphasetonuclei.atthesame

    ;time.thefunctionofTirestrictingthegrowthofAlphase

    ;increases.Correspondingly,theresultscanbeobtainedthat ;thesecondaryDASofAlphasedecreases,thesizeofthe

    ;eutecticSiparticlesdecreasesandbecomesmoreuniformand ;finer.SO.mealloywiththehigherstrength.higherhardness ;andbetterwearresistancecanbeachievable.WhenTicontent ;inexperimentalalloysismorethan0.12wt.%.itperhapsresult ;incollecting,growingupandprecipitatingofTi(AllxSix)3

    . ;particlesl6

    ;RefiningfunctionofTiappearsfading.Itcan

    ;beknownfromabovethatthedistribution,sizeandshapeof ;theeutecticSiphasecansignificantlyinfluenceonthewear ;resistanceoftheeutecticA1SiZL108alloys.

    ;3Conclusions

    ;(1)TheadditionofTielementintheeutecticAlSiZL108

    ;pistonalloyscanrefinethemicrostructure;changetheUTS ;at300?andHVhardnessofthealloys.WhenTicontent

    ;inthealloysreaches0.08wt.%0.12wt.%.thebetterrefined

    ;micrOstructure.superiorUTSat300?andHVhardness

    ;areachieved,suchas135.94MPainUTSandHV141.7in ;hardness,respectively.

    ;(2)ThewearmechanismoftheeutecticAlsiZL108piston

    ;alloysunderlubricatingconditionisabrasivewear.Thebroken ;siliconphasesareoneofsourcesofabrasivemateria1.Thehigher ;strengthandHVhardnessvaluesimpmvethewearresistanceof ;experimentalalloyswhichhave0.08wt.%-0.12wt.%Ticontent. ;(31ItisrevealedthattheoptimumTicontentintheeutectic ;AlSiZL108pistonalloyslaysbetween0.08wt.%_0.12wt.%. ;whentheelectrolyticlowtitaniumaluminiumalloysappliedto ;makepistons.

    ;165

    ;

    ;????CHINAFOUNDRY

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    ;

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