简介:ThemicrostructureandtensilepropertiesofSn-9Znsolderunderdifferentcoolingandagingconditionwerestudied.Duringsolidification,thedistributionofZn-richphasesandgrainsizeinthemicrostructureofSn-9Znsolderweredecidedbythecoolingrate.TheZn-richphaseinSn-9Znsolderunderfurnacecooling,aircoolingandwatercoolingmediawasseparatelyexistedascoarsendendriticandneedlelikeshape,fineneedlelikeshapeandveryfinerod-likeshape,respectively.Afteraging,thecoarsendendriticwasbrokenandthecoarsenneedlelikeZn-richphasewaspartlychangedintofinedistributionofZn-richphaseforSn-9Znsolderwithfurnacecooling,andtherod-likeZnphaseintheSn-9ZnsolderunderwatercoolingwaschangedtoconglomeratedZnwithneedleshape.DuringtensiletestingonSn-9Znsolder,tensilestrengthandductilityreachedthebestwithwatercooling,butdecreasedwithagingeffect.Meanwhile,theductilityofsolderwithaircoolingandthestrengthofsolderwithfurnacecoolingincreasedwithaging.Thefracturemodewasductileandwasindependentofcoolingmediaandagingeffect.Thesizeanddepthofdimplesdecreasedfromwater,furnacetoaircooling.Afteraging,numberandsizeofdimplesincreasedonthesolderwithfurnacecoolingandaircooling.ThechangeonthesizeofdimplesfortheSn-9Znsolderunderdifferentcoolingconditionandwithagingeffectwasaccordancetothetensileproperties.
简介:Carbonnanotube(CNT)reinforcedaluminummetalmatrixcompositeswereweldedbyelectronbeamweldingandthemicrostructuresofweldedjointswereinvestigated.TheresultshowedthattheinterfacialreactionhappenedbetweentheCNTsandAlmatrix,whichresultedinproducingbrittleAl_4C_3compoundsinelectronbeamwelds.Theextentofinterfacialreactionvariesgraduallyinthedepthandwidthdirection.ThelengthofthereactantsAl_4C_3becameshortduotothetemperaturegradientinthemoltenpool.ThequantityandsizeofAl_4C_3compoundsincreasedwiththeincreaseofbeamcurrentandthedecreaseofweldingspeedinthemiddlezoneofweld.However,noneedle-likephaseAl_4C_3wasobservedinHAZ.
简介:BondingofAl2O3tocuisperformeddirectlyusingTifoilattemperatureof1273K.Themicrostructureofthejointinterfaceisinuestigatedthroughscanningelectronmicroscope(SEM),electron.probemicroanalysis(EPMA)andX-raydiffraction(XRD).theeffectoftheinitialtifoilthicknessonthereactionlayerthicknessandthejointStrengthareinvestigated.
简介:ThefrictionandwearbehaviorofFe-Alintermetallicsbasedcoatingproducedbyhighvelocityarcsprayingtechniqueunderdryslidingatroomtemperaturewereinvestigatedusingaball-on-disctribotester.Theeffectofslidingspeedonfrictioncoefficientandwearofthecoatingwasstudied.Thewornsurfaceofthecoatingwasanalyzedbyscanningelectronmicroscope(SEM)toexploreslidingfrictionandwearmechanism.Theresultsshowthatthevariationsoffrictioncoefficientcanbedividedintothreedistinctstepsduringthetrail.Boththefrictioncoefficientandthewearofthecoatingincreasewithincreasedslidingspeedduetoacceleratedcrackpropagationrateandlamellarstructurewithpoorductilityofthecoating.Thecoatingsurfaceissubjectedtoalternatelytensilestressandcompressionstressduringslidingwearprocess,andthepredominantwearmechanismofthecoatingsappearstobebrittlefractureanddelamination.
简介:我国是铝的第一生产大国,但是在上世纪80年代初,因铝导体生产工艺低下严重影响了铝导体的使用。主要制约铝导体推广和使用因素是达不到国际公认的61%IACS导电率水平,以及与导电率相矛盾的断裂强度与伸长率,这就严重地制约了铝导体的使用。随着科学技术的不断发展,铝导体加工工艺的不断进步,人们想出了可在铝的熔炼过程中加入一些其他元素,来弥补铝导体性能的不足,发展到今天就形成了铝合金导体。从2005年开始,铝合金导体在电缆中的使用逐步发展起来,由于铝合金导体除了在导电率上与铜存在差距,在导体压蠕变、柔韧性、抗腐蚀以及电缆敷设方面都优于铜导体电缆,同时,在导电率上也可以通过扩大导体截面来弥补载流量的缺陷,从而人们也慢慢开始使用铝合金材料作为电缆导体。
简介:Theelectronbeamwelding-brazingbeingusedtojoin5A06AlalloytoTC4Tialloydecreasestheformationofbrittleintermetalliccompound.Experimentswerecarriedouttostudytheinfluenceofelectronbeamweldingparametersonthetensilestrengthofwelds,basedonanorthogonaltestandanalysismethod.Theweldingparametersincludebeamcurrent,weldingspeed,scanningfigure,scanningfrequency,figuresize,beamoffsetandfocuscurrent.Theoptimumparametersfor3mm5A06Alalloyand2mmTC4alloywereasfollows:accelerationvoltagewas60kV,beamcurrentwas11mA,weldingspeedwas600mm/min,focuscurrentwas0mA,scanfigurewasO,scanningfrequencywas1000Hzandbeamoffsetwas0.5mm.Theresultsshowthatthejointswerewithgoodappearanceandqualityweldedbytheoptimumparameters.ThesuccessfuljointscouldbegainedandthemaximumtensilestrengthofAl/Tidissimilaralloyjointscouldbeupto222.61MPausingelectronbeamwelding-brazing.
简介:ThispaperintroducesabrazingprocessbetweenAl_2O_3ceramicandInvaralloy.Al_2O_3canbebrazedwithInvareffectively.TheinterfacialstructureofAl_2O_3/Invarjointcanbeexpressedas:Invar/Ag(s,s)+Cu(s,s)+Fe_2Ti(zoneⅠ)/Ag(s,s)+Cu(s,s)+Fe_2Ti+NiTi+Cu_3Ti(zoneⅡ)/Ag(s,s)+Cu(s,s)+Cu_2Ti+Al(s,s)+TiC+TiO(zoneⅢ)/Al_2O_3.Themaximumshearstrengthof139MPawasmeasuredforas-brazedAl_2O_3/Invarjointbrazedat850℃for25minor900℃for15min.
简介:Forthedevelopmentofalow-melting-pointfillermetalforbrazingaluminumalloys,aseriesofAl-Si-Cu-(Ni,Sn,Zn)fillermetalshavebeenstudied.Throughdifferentialthermalanalysis(DTA),themeltingtemperaturesofsuchAl-Si-Cu-(Ni,Sn,Zn)fillermetalsweredetermined.Theresultsshowthattheadditionof3wt.%-5wt.%SnintotheAl-6Si-15Cufillermetalcausesitssolidustemperaturetodecreasebyabout12℃.ThefillermetalwiththecompositionAl-6Si-l5Cu-2Niisproposed,whichpossessesameltingtemperaturerangeof512℃to520℃andamicrostructarethatincludesanAl-Cueutecticphases,Al-Si-Cueutecticphases,siliconparticlesandCu_2Al,AlNi_3,Al_7Cu_4NiandAl_3Ni_2intermetalliccompounds.Anadditionof5wt.%-7wt.%ZnintosuchAl-Si-Cufillermetalscausetheirsolidustemperaturestodropfurthertoavaluelowerthan498℃.MetallographicobservationsindicatethattheadditionofZnintotheAl-Si-CufillermetalinhibitstheformationoftheAl-Si,Al-CuandAl-Si-Cueutecticphases.TheremainingphasesareaAl_2Cuintermetalliecompound,anα-Alsolidsolutionandsiliconparticles.
简介:Themicrostructureandmechanicalpropertiesofsteel/Alstructurematerialproducedbyadditivemanufacturing(AM)wasinvestigatedinthisworkbasedonthecoldmetaltransferwelding.Theresultsshowthatthemicrostructuregraduallychangedfromthesteelsidetothealuminumside.Themicrostructureinthesteellayerconsistedofvermiformlike8ferriteandaustenitestructure,whileinthealuminumlayerthemicrostructurewasconstitutedbyα-AlgrainsandtypicalreticulatedistributiveAl-Sieutecticstructure.Besides,a7μmthicknessNi-Alintermetalliccompoundlayerwasemergedattheinterfaceofnickelandaluminumlayer.Themaximumroom-temperaturetensilestrengthoftheSteel-Alstructurematerialswasfoundtobe54MPa,therupturemorphologyshowedabrittlefracturecharacteristic.
简介:TheAl-alloyarc-weldingshapingsystembasedonarc-weldingrobotisestablished,andtheAl-alloyshapingmanufactureisrealizedwiththeDC(directcurrent)gasmetalarcwelding(GMAW).TheresearchindicatesthatthemetaltransfertypeofDCGMAW,heatinputandtheinitialtemperatureoftheworkpiecegreatlyaffecttheAl-alloyshapingbasedonarcweldingrobot.Onthepenetration,theweldwidthandthereinforcement,theinfluenceofweldingparametersisanalyzedbygeneralizedregressionneuralnetwork(GRNN)fitting.