简介:ThesubmicronpowdermixturesofTiC-TiN-WC-Mo-C-Nisinteredat1400℃orbelowinvacuumwerestudiedbyX-raydiffraction(XRD),scanningelectronmicroscopy(SEM)andtransmissionelectronmicroscopy(TEM)analyses.TheresultsshowedthatMo2Cformedat800℃orbelow.BothWCandMo2Cdisappearedat1200℃,andTiNdisappearedat1250℃.Inaddition,thevariationsoflatticeconstantsofthetitaniumcarbonitrideandnickelbinderphasewithsinteringtemperaturewereexperimentallyobtained,andthereasonwasanalyzed.
简介:Anewhardfacingprocess,reactivebrazecoatingprocess(RBCC)wasstudied,and(TiC+Cr3C2)/FecompositecoatingswerepreparedbyRBCCusingcarbon,Cr3C2,iron,ferrochromiumandtitaniumpowderastherawmaterialsinvacuumbrazefurnace.TheresultsshowthatTiCisin-situsynthesizedinthecoatings.ThemethodsofintroducingCr3C2havegreateffectsonthedistributionofTiC.AddingCr3C2directlytotherawmaterialsforcoatings,fineTiCparticlesaggregateintodiscoidsparalleltothecoatingsurface,whereas,in-situsynthesizingCr3C2incoatings,theaggregationsofTiCarelumpish.Duringbrazecoating,Cr3C2particlesdirectlyaddeddissolveandprecipitatetobecomeneedle-shaped.Thecoatingshaveanevenandsmoothsurfaceandarecombinedwiththeirmildsteelsubstratesbyametallurgicalbonding.
简介:Basedonalargeamountofdissectionatweldedinterfaceandquantitativemicroscopicexaminationofweldedrate,thesuitablelimitgreyscalevaluewasdetermined,andtheweldedrateofsuperplasticsolid-stateweldinginterfaceofheterogeneoussteelwassystematicallystudiedbymeansofself-madeultrasonicC-scanningimaginginspectionsystem.Theexperimentalresultsshow:theweldedstateofsuperplasticsolid-stateweldinginterfaceofheterogeneoussteelcanbeconductedtobemoreaccurately,reliablyandquicklyinspectedbymeansofthissystem,andtheultrasonictestingresultsaregoodconsistentwithactualexaminationresultsoftheinterfacedefectivedistribution.Withintheextentofthesuitbleweldedrate,theweldedratein40Cr/T10Asuperplasticweldingprocesstestedbythissystemislinearwithitstensilestrengthofjoint.
简介:EffectsofalloyelementsonthemicrostructureandcrackresistanceofFe-C-Crweldsurfacinglayerwereinvestigated.Theresultsshowthatmicrostructuresofthelayermainlyconsistofcarbidesandaustenitematrix.IncreasingCandCrcontentsimpairthecrackresistanceofthelayerduetoincreasedamountofbrittlecarbides.TheadditionofNi,NborMoimprovesthecrackresistanceofFe-C-CrweldsurfacinglayerbyincreasingtheamountofausteniteandformingfineNbCorM7C3carbidesinthelayer.But,theexcessiveNb(>2.50wt%)orMo(>1.88wt%)impairsthecrackresistanceofthelayer,whichhasrelationwithincreasedcarbidesorcarbidecoarseningandaustenitematrixsolidsolutionstrengthening.ThepropercombinationofC,Cr,Ni,NbandMocanfurtherimprovenotonlythecrackresistanceofFe-C-CrweldsurfacinglayerbutalsotheerosionresistanceasaresultoffineNbCandM7C3carbidesdistributinguniformlyinaustenitematrix.Theoptimallayercompositionsare3.05wt%C,20.58wt%Cr,1.75wt%Ni,2.00wt%Nband1.88wt%Mo.
简介:在二种铝锂alloys2090和2090+Ce的脱臼的微观结构借助于TEM技术被观察。到力量的8''和T_1precipitates的贡献被使用量的金属组织学的结果和微变丑的行为的分析独立计算;三角洲的共同加强的效果“andT_1猛抛被学习。结果证明三角洲共同加强的增加的关系“并且T_1根据1.4以近的山峰条件形成的q=,即,三角洲tau_p~(1.4)=三角洲字形物_(三角洲“)~(1.4)+三角洲字形物_(T_1)~(1.4);但是增加的关系是近似一种线性关系(q=1)以未成年的条件并且成为抛物线形式什么时候over-aged(q=2)。共同加强的增加的关系三角洲的贡献“并且显然依赖于老化时间的T_1is。
简介:1IntroductionTherareearthcobaltalloyshavethepotentialformakingthemagneticandmagnetoopticalmaterials.Sofar,therareearthcobaltalloyfilmsaresubstantiallyproducedbysputteringorvacuumplating.Ifsuchfilmsarepreparedbyelectrodepositioninstead,productionefficiencywouldbeimprovedandthecompositionofthealloycouldbecontrolled.Becausetheoxidationreductionpotentialsofrareearthelementsareverynegative,organicsolventsmaybeusedaselectrolyticmedia.ElectrodepositionofGdCoandSmCoinorganicsolutionshasbeenreporte...
简介:作为材料的重要性质之一,硬度一直受到人们广泛的重视和研究。Cohen和Liu利用第一性原理计算从理论上预言了一种超硬性能的新材料β—C3N4,其体积弹性模量超过金刚石。CVO3组采用微波等离子体化学气相沉积法(MPCVD),用高纯N2(99.999%)和CH4(99.9%)作反应气体,在单晶Si(100)和多晶Pt衬底上沉积碳氮薄膜,开展了对β-C3N4薄膜的制备与表征的探索性研究,取得了一定的进展。