简介:Puretungsten(PW)andW-1wt%La2O3(WL10)werepreparedbypowdermetallurgicalroutefollowedbytheswaging+rollingprocess.Thelogarithmicstrainsare0,0.37,0.58,and0.98forWL10and0,0.58forPW.Heattreatmentswereperformedattemperaturesvariedfrom1,573to2,173Ktodeterminetherecrystallizationtemperature.Recrystallizationtemperaturesare1,973and2,173KforWL1(logarithmicstrainof0.37)andWL3(logarithmicstrainof0.98),respectively.ButinthecaseofWL2(logarithmicstrainof0.58),fullrecrystallizationisnotachievedattemperatureofabove2,173K.Furthermore,therecrystallizationtemperatureofPWwithlogarithmicstrainof0.58isatleast300KlowerthanthatoftheequivalentWL10sample.Moreover,theincreaseofrecrystallizationtemperatureinhibitsthestrengthdegradationofWL2:sampleslose4%and22%strengthwhenannealedat1,573and1,973Kcomparedwithroomtemperature(RT)sample.Finally,thetextureevolutionfortheswaged+rolledWL10issignificantlyrelatedtothedeformationdegree:thedominatedorientationis<001>forWL2while<110>forWL3.
简介:Athree-dimensionalsimulationmodelfortheplasma-MIGweldingprocess,whichtakestheinteractionbetweentheplasmaarcandMIGarcintoaccount,ispresentedandthequasi-steadytemperaturefieldsontheworkpiecearecalculatedwiththemodel.The10mm-5A06aluminumalloyisweldedandthetemperaturefieldsaremeasuredwiththethermoelectriccouple.Thesimulationresultsandmeasuredresultsshowthatthebiggestdeviationofpeaktemperaturebetweenthemisbelow20℃,whichindicatesgoodcoincidencebetweenthesimulationandmeasurement.
简介:Theaxialandradialconvectiveflow,temperaturefluctuationanddistributionintheHMCZsiliconmeltarestudiedtentatively.Theexperimentalresultsshowthattheaxialandradialconvectivespeeds,thetempera-turevariationandtheradialtemperaturegradient,paralleltomagneticfieldandnearmeltsurface,alldecrease,buttheaxisymmetryoftemperaturedistributionnolongerexistswhenthemagneticfieldisapplied.
简介:Permanentmagneticmaterialscapableofoperatingathightemperatureupto500°Chavewidepotentialapplicationsinfieldssuchasaeronautics,space,andelectroniccars.SmCoalloysarecandidatesforhightemperatureapplications,sincetheyhavelargemagnetocrystallineanisotropyfield(6–30T),highCurietemperature(720–920°C),andlargeenergyproduct([200kJám-3)atroomtemperature.However,thehighestservicetemperatureofcommercial2:17typeSmComagnetsisonly300°C,andmanyeffortshavebeendevotedtodevelopnovelhightemperaturepermanentmagnets.ThisreviewfocusesonthedevelopmentofthreekindsofSmCobasedmagnets:2:17typeSmComagnets,nanocrystallineSmComagnets,andnanocompositeSmComagnets.Theoxidationprotection,includingalloyingandsurfacemodification,ofhightemperaturepermanentmagnetsisdiscussedaswell.
简介:Thecombinedquadraticorthogonalregressionmethodofexperimentdesignwasemployedtoexploretheeffectsofprocessparametersofplasmanitridingoftantalumsuchastotalpressure,temperatureandoriginalhydrogenmolarfractiononthehardness,roughnessandstructureofnitridingsurfaces.Theregressionequationsofhardness,roughnessandstructureweregivenaccordingtotheresultsofregressionandstatisticanalysis.Andthediffusionactivationenergyofnitrogenintantalumonplasmanitridingconditionswascalculatedaccordingtotheexperimentaldataofhardnessofplasma-nitridingoftantalumvstimeandtemperature.Thediffusionactivationenergycalculatedbelongsto(155.49+10.51)kJ/mol(783-983K).
简介:IntroductionIMI829titaniumaloyisakindofhightemperaturenearαaloy.Itsservicetemperatureisupto580℃.IthasbeenusedinRB211525E4en...
简介:Theinfraredcameraisusedtoinvestigatethetemperaturefieldofgasmetalarcwelding.Theresultsshowthatthetemperaturedistributionofweldpoolandadjacentareaappearsconeshape.AnewheatsourcemodelcombinedbyGaussiandistributionheatsourceofthearcandconicaldistributionheatsourceofthedropletissetupbasedontheexperimentalresults,andwiththecombinedboundaryconditions,thetemperaturefieldofgasmetalarcweldingissimulatedusingfiniteelementmethod.AccordingtothecomparisonbetweentheresultsofexperimentandsimulationintemperaturefieldshowsthatthenewcombinedheatsourcemodelismoreaccurateandeffectivethantheGaussheatsourcemodel.
简介:Ni83Fe17filmswithathicknessofabout100nmweredepositedonthermaloxidizedsiliconsubstratesatambienttemperature,240,350,and410℃byDCmagnetronsputtering.Thedepositionratewasabout0.11nm/s.Theas-depositedfilmswereannealedat450,550,and650℃,respectively,inavacuumlowerthan3x10-3Pafor1h.TheNi83Fe17filmsmainlygrowwithacrystallineorientationof[111]inthedirectionofthefilmgrowth.Withtheannealingtemperatureincreasing,the[111]orientationenhances.Forfilmsdepositedatallfourdifferenttemperatures,thesignificantimprovementonanisotropicmagnetoresistanceoccursattheannealingtemperaturehigherthan550℃.Butforfilmsdepositedatambienttemperaturesand240℃,theanisotropicmagnetoresistancecanonlyrisetoabout1%after650℃annealing.Forfilmsdepositedat350℃and410℃,theanisotropicmagnetoresistancerisestoabout3.8%after650℃annealing.Theatomicforcemicroscopy(AFM)observationshowsasignificantincreaseingrainsizeofthefilmdepositedat350℃atter650℃annealing.Thedecreaseinresistivityandtheincreaseinanisotropicmagnetoresistancearecausedbythedecreaseinpointdefects,theincreaseingrainsize,andtheimprovementinlatticestructureintegrityofthefilms.
简介:Theeffectofsolidificationrateonthemicrostructuredevelopmentofnickel-basedsuperalloyunderthetemperaturegradientof500K·cm-1wasstudied.Theresultsshowthat,withtheincreaseofdirectionalsolidificationratefrom50to800μm·s-1,boththeprimaryandthesecondarydendritearmspacingsofthealloydecreasegradually,andthedendritemorphologiestransformfromcoarsedendritetosuperfinedendrite.Thesizesofallprecipitatesinthesuperalloydecreasegradually.Themorphologyof...
简介:Threekindsofmathematicalmodelsrepresentingweldingheatsourcesarepresented.Amongthem,Gaussianmodelanddoubleellipsoidalmodelareusedtoanalyzethethermaldistributionswithfiniteelementmethod.Atthesametime,thispaperanalyzedtheinfluencesoftheheatsourcemodels,thelatentheatandtheweldingparametersonthetemperaturedistributions.Thecomparisonsbetweenthesimulatedresultsandtheexperimentsshowdoubleellipsoidalmodelisgoodforthree-dimensionalnumericalsimulations.Furthermore,theadaptivemeshtechniqueisappliedinthethree-dimensionalmodelwhichgreatlyreducesthenumberofnodesandelementsinthesimulation.
简介:Theaccuratecalculationandmeasurementofweldingtemperaturefieldisanimportantpreconditionforweldingmetallurgicalanalysisandweldingprocesscontrolling.Inthispaper,theconformaltransformationisfirstlyusedtoanalyzetheweldingtemperaturefieldoffeatheredgedcylinder.Thecenterofthecylinderischosenastheoriginofcolumncoordinatesystem,andeverypointmaybeexpressedascomplexfieldvector.Thebranchisogonalitycounterchangesthelineparallelwiththefusionlineinhalf-infinitez-planetothecircleconcentricwiththefusionlineininfinitecylinder.TheLaplaceequationandPoisson'sequationstillkeepvalidity,sothetemperaturefieldequationcanbesolved.TheconformaltransformationandequationsolutionisprocessedbyMatlabprogramlanguage.Itshowsthattheobtainedanalyticalmodelingoftemperaturefieldforfeatheredgedcylinderbasedonconformaltransformationiseffectiveandaccurate.
简介:Theliquid-filmsolution-diffusionbondingofZCuBe2.5alloyswasconductedusingCu-basedalloypowders.Thetensilestrengthofthebondingtimedecreasesandtheinterfacemigrationvelocityincreasesbondingtime,thethicknessofdiffusionlayerincreaseswiththeincreaseoftemperaturegradient,andthistendencybecomesmoreremarkablewiththeprolongingofbondingtime.
简介:1IntroductionOverthepastfewyears,intensiveworkhasbenmadetoachievemulticolororfulcolorthinfilmelectroluminescence(EL)device...