学科分类
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17 个结果
  • 简介:TheevolutionofmicrostructureandmechanicalpropertiesofAl-0.4Cu-0.14Si-0.05Mg-0.2Fe(wt.%)alloys,micro-alloyedwithZr,TiandSc,wereinvestigated.Theadditionof0.2%ZrtobasealloyacceleratestheprecipitationofSi-richnano-phaseinα-Almatrix,whichplaysanimportantroleinimprovingthemechanicalpropertiesofanalloy.Thetensilestrengthincreasesfrom102MPaforthebasealloyto113MPafortheZr-modifiedalloy.Adding0.2%Zr+0.2%Titobasealloyeffectivelyrefinesa-AlgrainsizeandacceleratestheprecipitationofSiandCuelements,leadingtoheavysegregationatgrainboundary.Byfurtheradding0.2%SctoZr+Timodifiedalloy,thesegregationofSiandCuelementsissuppressedandmoreSiandCuprecipitatesappearedinα-Almatrix.AccompaniedwiththeformationofcoherentAl3Scphase,thetensilestrengthincreasesfrom108MPafortheZr+Timodifiedalloyto152MPafortheSc-modifiedalloy.DuetoexcellentthermalstabilityofAl3Scphase,theSc-modifiedalloyexhibitsobviousprecipitationhardeningbehaviorat350℃,andthetensilestrengthincreasesto203MPaafterholdingat350℃for200h.

  • 标签: Micro-alloying MICROSTRUCTURE Mechanical properties AL3SC GRAIN
  • 简介:FenanowirearraywithstrongshapeanisotropywasemployedasthesoftphaseinNd-Fe-Bbasednanocomposites.TheeffectsoftheFenanowiredistributiononmagneticpropertiesofthenanocompositeswereinvestigatedbymicromagneticsimulation.TheresultsindicatethattheshapeanisotropyofFewiresaddedinthesamedirectionastheuniaxialmagnetocrystallineanisotropyofthehardphasecannotincreasethecoercivityofthenanocomposite.Whenthenanowiresaredistributedperpendiculartotheeasyaxisofthehardphase,theshapeanisotropyofsoftphasecanretardthemomentsfromrotatingtothefullreverseddirection,leadingtoenhancedcoercivity.Inaddition,withincreasingthenanowirediameter,thecoercivityofthenanocompositedecreases,butthedipolarinteractionshowsdifferentrolesinmagneticreversalofnanocompositefordifferentdistributionsofnanowires.ThecurrentresultssuggestthatthecoercivityoftheNd2Fe14B/α-Fenanocompositecanbeenhancedbyintroducingthesoftmagneticnanowirearraywiththediameterlessthantheexchangelengthandwiththelongaxisalongthedirectionotherthantheeasyaxisofhardphase.

  • 标签: Nd2Fei4B/α-Fe NANOCOMPOSITE MICROMAGNETIC simulation FE NANOWIRES
  • 简介:用无溶剂复合PET和VMPET以及PET/AL这种两种基材都是高阻隔材料的结构,目前是个难题,尤其是满版白墨或黄墨的印刷膜复合,难度更大。

  • 标签: 无溶剂复合 PET AL 成熟 高阻隔材料 印刷
  • 简介:AdditionofAl-5Ti-1Balloytomoltenaluminumalloyscanrefineα-Algrainseffectivelyandtherebyimprovetheirstrengthandtoughness.TiAl3andTiB2inAl-5Ti-1Balloyarethemainsecondary-phaseparticlesforrefinement,whiletheunderstandingontheeffectoftheirsizesonα-Algrainrefinementcontinuestobefragmented.Therefore,Al-5Ti-1Balloyswithvarioussizesandmorphologiesofthesecondary-phaseparticleswerepreparedbyequalchannelangularpressing(ECAP).Evolutionofthesecondary-phaseparticlesduringECAPprocessandtheirimpactonα-AlgrainrefinementwerestudiedbyX-raydiffractionandscanningelectronmicroscope(SEM).ResultsshowthatduringtheECAPprocess,micro-cracksfirstlyappearedinsideTiAl3particlesandthengraduallyexpanded,whichresultedincontinuousrefinementofTiAl3particles.Inaddition,micro-distributionuniformityofTiB2particleswasimprovedduetotheimpingementofTiAl3particlestoTiB2clustersduringdeformation.ExcessivelylargesizesofTiAl3particleswouldreducethenumberofeffectiveheterogeneousnucleusandthusresultedinpoorgrainrefinementeffectiveness.Moreover,excessivelysmallTiAl3particleswouldreduceinhibitoryfactorsforgraingrowthQandweakengrainrefinementeffectiveness.Therefore,anoptimalsizerangeof18-22μmforTiAl3particleswassuggested.

  • 标签: Equal channel ANGULAR PRESSING process Secondary
  • 简介:Tensileandfracturebehaviorsofsandwich-structuredcompositesconsistingofaFe-basedamorphouslayerwithaconstantthicknessandultrafine-grainedNilayerswithdifferentthicknesseswereinvestigated.TheresultsindicatethattheinitiationandthestablepropagationoftheshearbandintheamorphouslayerwasdominatedbytheNilayersduetotheirstrongconstraintrole.ThecatastrophicfractureoftheamorphouslayerwaspostponedinthesandwichcompositesthroughproperlyincreasingtheconstrainedNilayerthickness,whicheffectivelydecreasedtheshearstressontheshearfractureplanesoftheamorphouslayer,andthusledtostablepropagationoftheprimarySBcharacterizedbytheincreaseinthesmoothregionsizeoftheshearband.

  • 标签: Sandwich-structured composites AMORPHOUS alloy Shear stability
  • 简介:来自英国曼彻斯特大学和中南大学的科学家团队设计并制造了一种可以彻底改变高超音速旅行的新型硬质合金涂层。温度在以5马赫或以上(音速的5倍)行进的物体外部可以飙升至2000℃至3000℃,导致其表面发生破坏性氧化和烧蚀。

  • 标签: 硬质合金涂层 极端高温 曼彻斯特大学 高超音速 中南大学 科学家
  • 简介:Excessiveconsumptionofelectricalenergyhashamperedthewidespreadapplicationofelectrochemicaltechnologyfordegradationofvariouscontaminants.Inthispaper,aFe-basedmetallicglass(MG)wasdemonstratedasanewtypeofelectrocatalysttoeffectivelyandeconomicallydegradeanazodye.Incomparisontoothertypicalelectrodes,Fe-basedMGelectrodesexhibitaminimizeddegradationtime,andthespecificenergyis4-6ordersofmagnitudelowerthanthatofdimensionallystableanode(DSA),metal-likeboron-dopeddiamond(BDD)andotherelectrodes.Assacrificialelectrodematerials,Fe-basedMGshavelessspecificelectrodemassconsumptionthanironelectrodes.TheuseofFe-basedMGswillpromotethepracticalapplicationofelectrochemicaltechnologyandtheuseofMGsasfunctionalmaterials.

  • 标签: Metallic GLASSES Azo DYES Electrochemical degradation
  • 简介:Theyolk-shellFe3O4@Cnanocubesweresuccessfullysynthesizedthroughcarbothermicreductionprocessfromcarbon-coateda-Fe2O3precursor.Theresultsshowthattheyolk-shellFe3O4@Cnanocubesareuniformlycoatedwithathincarbonlayer,andaclearcavityabout150nminwidthbetweenFe3O4coreandcarbonshellareformedduetothevolumeshrinkageduringthereductiontreatment.Theobtainedyolk-shellFe3O4@Cnanocubesexhibitexcellentcyclingstability(thedischargecapacityis709.7mAh/gafter100cyclesatthecurrentdensityof0.1C)andrateperformance(1023.4mAh/gat0.1C,932.5mAh/gat0.2C,756.1mAh/gat0.5C,405.6mAh/gat1C,and332.3mAh/gat2C,andmoreimportantly,whenthecurrentdensityfinallybacksto0.1C,acapacityof776.8mAh/gcanberestored).Theoutstandinglithiumstoragepropertiesmaybeattributedtotheuniqueyolk-shellstructures.

  • 标签: Fe3O4 yolk-shell nanocube ANODE lithium STORAGE
  • 简介:Themicrostructureevolutionandphasecompositionofanα+βtitaniumalloy,Ti-3Al-5Mo-4.5V(wt.%),havebeeninvestigated.Electronprobemicroanalysis(EPMA)quantitativeresultsmanifestthatthestabilityofβphasedecreaseswithincreasingquenchingtemperature,whichisinfluencedbythesignificantvariationofβ-stabilizingelementsconcentration.Detailedmicrostructureanalysisshowsthattheβ→ωphasetransformationdoesoccurwhenquenchingat750℃and800℃.Theω-reflectionschangefromincommensurateω-spots(750℃)toidealω-spots(800℃)astheβstabilityofthealloydecreases.Furtherthedecreaseofβphasestabilityencouragestheformationofathermalα"martensite,whichhasthefollowingorientationrelationships:[111]β//[110]α",[100]p//[100]α"and[-110]p//[00-1]α"withrespecttotheβmatrix.

  • 标签: DUAL-PHASE titanium ALLOY β PHASE STABILITY
  • 简介:Inthepresentstudy,aseriesofregenerationconditionsandtheregenerationmechanismofmodifiedlakesedimentbiochar(Fe-KOH/LSB)catalystsforlow-temperaturecatalytichydrolysisofcarbondisulfide(CS2)wereinvestigated.TheresultsshowedthatRm-WNAmethodhadthebestregenerationeffect.Underoptimalregenerationconditions,thesulfurcapacity(13.86mg[s]/g[catalyst])ofregeneratedFe-KOH/LSBwasclosetothatoffreshFe-KOH/LSB(14.88mg[s]/g[cataiyst]).Thewaterwashingprocesscouldwashawayasmallnumberofsulfatesandalargenumberofalkalinegroups.TG-DTAandDRTFIRresultsindicatedthatthenitrogensweepingprocesscoulddecomposeFe2(SO4)3intoFe2O3,whichpartiallyrecoveredthecatalyticandtheadsorptiveabilities.CO2-TPDresultsindicatedthatthealkalisteepingprocessoffer-OHgroups,furtherimprovingthecatalyticandtheadsorptiveabilities.After3times-regeneration,thesulfurcapacityofFe-KOH/LSBreached13.31mg[s]/g[cataiyst],indicatingthattheRm-WNAmethodhadgoodstabilityfortherecoveryofthecatalyticactivity.BET,XPSandXRDresultsrevealedthatthedecreaseofthesulfurcapacityforregenerationwasattributedtothedecreaseoftheadsorptiveabilitiesofCandSiO2.

  • 标签: REGENERATION condition modified lake sediment REGENERATION
  • 简介:Thisstudywasconductedtodiscusstheeffectofrollingstrainonmicrostructureandtensilepropertiesofdual-phaseMg-8Li-3Al-2Zn-0.5Y(wt%)alloy,whichwaspreparedbycasting,andthenhomogenizedandrolledat200℃.Therollingprocesswasconductedwith10%reductionperpassandfivedifferentaccumulatedstrains,varyingfrom10%to70%.Theresultsindicatethattheas-castandas-rolledMg-8Li-3Al-2Zn-0.5Yalloysarecomposedofα-Mg,β-Li,AlLiandAl2Yphases.Afterrollingprocess,anisotropicmicrostructurewasobserved.a-Mgphasegotelongatedinbothrollingdirectionandtransversedirectionwiththeadditionofrollingstrain.Consequently,thestrengthofthealloyinbothdirectionswasnotablyimprovedwhereastheelongationdeclined,mainlycausedbystrainhardeninganddispersionstrengthening.Thetensilepropertiesoftheas-rolledalloysintheRD,nomattertheYS,UTSortheelongation,arehigherthanthoseoftheTDduetotheirlargerdeformationstrainandsignificantanisotropyinthehcpα-Mgphase.Inaddition,thefractureandstrengtheningmechanismofthetestedalloyswerealsoinvestigatedsystematically.

  • 标签: Mg–8Li–3Al–2Zn–0.5Y ROLLING ANISOTROPY TENSILE properties STRAIN
  • 简介:这研究调查低温实验法的张力的性质和小说的破裂行为搅动焊接并且32Mn-7Cr-1Mo-0.3N钢的焊接以后的对待热的关节。低温实验法的易碎的骨折,发生在同样焊接的关节,与在联合乐队结构包含钨的剩余粒子有关。韧化的焊接以后的水导致了关节的低温实验法的intergranular易碎物,它在韧化的焊接以后的水期间与溶质原子的非平衡分离有关。在550点退火吗??

  • 标签: 破裂行为 实验法 焊接 关节 低温 张力