简介:Arheo-diecastingprocess(RDC)wasinvestigatedforsemisolidprocessingofanAZ91Dmagnesiumalloy.TheresultsoftheRDCsamplesinas-caststateindicatethatthemicrostructureofprimaryα-Mgparticleshasafinesize,nearlysphericalmorphology,anduniformdistributionthroughoutthecomponents.Duetotheadvancedmicrostructureandreducedlevelofdefects,theRDCAZ91DMgalloyexhibitsanapparentimprovementinmechanicalproperties.Thequantitativemetallographicinvestigationsrevealthatincreasingtheintensityofforcedconvectionduringtheslurrypreparationresultsinapromotednucleationandreducedvolumefractionoftheprimaryphasesolidifiedintheslurrymaker.
简介:Inthisstudy,atwo-stepheatingprocessisintroducedfortransientliquidphase(TLP)diffusionbondingforsoundjointswithT91heatresistantsteels.Atfirst,ashort-timehighertemperatureheatingstepisaddressedtomelttheinterlayer,followedbythesecondsteptocompleteisothermalsolidificationatalowtemperature.Themostcriticalfeatureofournewmethodisproducinganon-planarinterfaceattheT91heatresistantsteelsjoint.WeproposeatransitionalliquidphasebondingofT91heatresistantsteelsbythisapproach.Sincejointmicrostructureshavebeenstudied,wetestedthetensilestrengthtoassessjointmechanicalproperty.Theresultindicatesthatthesolidifiedbondmaycontainaprimarysolid-solution,similarcompositiontotheparentmetalandfreefromprecipitates.Jointtensilestrengthofthejointisnotlowerthanparentmaterials.Jointbend'sstrengthsareenhancedduetothehighermetal-to-metaljunctionproducinganon-planarbondlines.Nevertheless,thetraditionaltransientliquidphasediffusionbondingproducesplanarones.Bondingparametersofnewprocessare1260℃for0.5minand1230℃for4min.
简介:通过化学沉积法制备Ni-P、Ni-Mo-P单镀层以及与其成分相同的Ni-P/Ni-Mo-P双镀层。采用纳米压痕法和AFM分析测量镀层表面和截面的残余应力,并用电化学法评估镀层在10%HCl溶液中的腐蚀行为,以获得镀层残余应力与腐蚀行为之间的关系。结果表明:Ni-P单镀层和Ni-P/Ni-Mo-P双镀层表现为残余压应力,分别为241和206MPa;Ni-Mo-P单镀层呈现出257MPa的残余拉应力。残余压应力阻止镀层中孔洞的生长,保护镀层的完整性。Ni-P/Ni-Mo-P双镀层比它们的单镀层具有更好的耐蚀性。此外,镀层的应力状态影响其腐蚀形式。
简介:Microstructuresandmechanicalpropertiesoftransientliquidphase(TLP)bondedmagnesiummetalmatrixcomposite(MMC)jointsusingcopperinterlayerhavebeeninvestigated.Withanincreaseofbondingtimesfrom5minto50minatbondingtemperatureof510℃,theaverageconcentrationofcopperinthebondedzonedecreased,themicrostructureinthezonechangedfromCu,α-MgandCuMg2toα-Mg,CuMg2andTiC,andmechanicalpropertiesofthejointincreased.Theshearstrengthofthejointbondedat510℃for50minreached64MPaduetothemetallurgicalbondingofthejointandimprovingitshomogeneityofcompositionandmicrostructure.ItisfavorabletoincreasethebondingtimeforimprovingmechanicalpropertiesofTLPbondedmagnesiumMMCjoint.
简介:为了对高合金异种钢焊接工艺有更多的了解,本文通过对某火力电厂锅炉后屏过热器检修换管过程中涉及到的钢种(SA213-T91马氏体高合金耐热钢与Cr25Ni13奥氏体高合金耐热钢)的现场焊接工艺进行介绍,以给类似工程的施工提供一定的借鉴。
简介:InordertocontrolthesizeanddistributionofthehighconductiveFe2PinLiFePO4/Fe2Pcomposite,twodifferentcoolingrates(Fast:15℃·min-1,Slow:2℃·min-1)wereemployedaftermechanicalalloying.Thedischargecapacityofthefastcooledwas83mAh·g-1andtheslowcooled121mAh·g-1.TheparticlesizeofthesynthesizedpowderwasexaminedbytransmissionelectronmicroscopyanddistributionofFe2Pwascharacterizedusingscanningelectronmicroscopy(SEM).Inaddition,two-stepheattreatmentwascarriedoutforbetterdistributionofFe2P.X-raydiffraction(XRD)andRietveldrefinementrevealthatLiFePO4/Fe2Pcompositeconsistsof95.77%LiFePO4and4.33%ofFe2P.
简介:Weldshapecontrolisafundamentalissueinautomaticwelding.Inthispaper,adoublesidevisualsystemisestablishedforpulsedgasmetalarcwelding(P-GMAW),andbothtopsideandbacksideweldpoolimagescanbecapturedandstoredcontinuouslyinrealtime.Byanalyzingtheweldshaperegulationwiththemoltenmetalvolume,sometopsideweldpoolcharacterizedparameters(WPCPs)areproposedfordeterminingpenetrationinbuttweldingofthinmildsteel.Moreover,someBPnetworkmodelsareestablishedtopredictbacksideweldpoolwidthwithweldingparametersandWPCPsasinputs.
简介:Thehotdeformationbehaviourof7075aluminiumalloyreinforcedwith10%ofSiCparticleswasstudiedbyemployingboth'processingmaps'andmicrostructuralobservations.Thecompositewascharacterizedbyemployingopticalmicroscopetoevaluatethemicrostructuraltransformationsandinstabilityphenomena.Thematerialinvestigatedwasdeformedbycompressioninthetemperatureandstrainraterangesof300-500℃and0.001-1.0s-1,respectively.Thedeformationefficiencywascalculatedbystrainratesensitivity(m)valuesobtainedbyhotcompressiontests.Thepowerdissipationefficiencyandinstabilityparameterswereevaluatedandprocessingmapswereconstructedforstrainof0.5.Theoptimumdomainsandinstabilityzonewereobtainedforthecomposites.Theoptimumprocessingconditionsareobtainedinthestrainraterangeof0.1-0.9s-1andtemperaturerangeof390-440℃withtheefficiencyof30%.
简介:55%SiCp/A356(体积部分)以铜锌金焊接在把Zn-Al合金用作filler金属的空中的composites被调查。在以铜锌金焊接的过程期间,超声的颤动为结合被用于样品,进在基础材料的矩阵合金的filler金属的重要溶解发生了。当以铜锌金焊接的温度被增加,在基础材料的部分融化层的厚度增加了。原文如此,在基础材料的部分融化层的粒子在超声的行动下面被变成液体filler,有同类地分布式的加强的一张契约在团结以后被获得。体积部分原文如此,在契约的粒子能被改变以铜锌金焊接的温度改变。最大值原文如此,契约材料的粒子体积部分在500的以铜锌金焊接的温度到达了37%?????????????敷摬摥??
简介:AmorphousNi–PcoatingwasplatedonAZ31magnesiumalloyviatheelectrolessplatingtechnique,andtheplatedalloywassubsequentlyannealed.X-raydiffraction(XRD),scanningelectronmicroscopy(SEM),energydispersivespectroscopy(EDS),anddifferentialscanningcalorimetry(DSC)wereusedtocharacterizethecoating.Theresultsshowthatthehardnessofthecoatingismuchhigherthanthatofbaremagnesiumalloy,whichfurtherincreasesaftercrystallization.Theelectrochemicalpolarizationandsaltspraytestsshowthatthecoatingexhibitsamuchhighercorrosionresistancethanthatofthebaremagnesiumalloy.Moreover,thecrystallizedcoatingstillexhibitsamuchstrongercorrosionresistancethanthatofthebaremagnesiumalloy,althoughitscorrosionresistanceislowerthanthatoftheas-platedone.