简介:TheDCcharacteristicsofSiGeHBTirradiatedatdifferentelectrondosehavebeenstudiedinacomparisonwiththoseofSiBJT.Generally,IbandIb-Ib0increase,Ic,Ic-Ic0andits+/-transitionVbeaswellasDCcurrentgainβdecreaseswithincreasingdose;increaseofIb-Ib0withincreasingdoseforSiBJTismuchlargerthanthatforSiGeHBT;βincreaseswithVbeorIb,butdecreasesatIb<0.25mAwithIb,andcongregatesathigherdose;andadamagefactord(β)ismuchlessatthesamedoseforSiGeHBTthanforSiBJT.SiGeHBThasmuchbetteranti-radiationperformancethanSiBJT.SomeanomalousphenomenaforincreaseofIc,Ic-Ic0,Ib-Ib0andβatlowdosehavebeenfound.Someelectrontrapshavebeenmeasured.Themechanismofchangesofcharacteristicsisdiscussed.
简介:MicrostructureandtextureofTi-Nb-Sibasedalloys,preparedbywaterquenchingfromβ-phasefield,coldrollingandrecrystallizationheattreatmentfollowedbywaterquenching,wereinvestigatedintermsofopticalmicrostructureandanalysisofX-raypolefigureresult.Inas-quenchedsample,relativelyrandomdistributionofpolefigurewasdetectedwithoutshowingaspecifictexturecomponent.Inas-coldrolledsample,however,itisfoundwell-developedseveraltexturecomponentsconsistingofrotatedcube,α-fiberandγ-fibertexturecomponentswhicharefrequentlyobservedinbcc-structuredmetalsandalloyswerefound.Therefore,texturecomponentsdevelopedinthepresentalloysarecloselyrelatedtothedeformationofβ-phaseeventhoughsmallamountofα″phaseco-existinthemicrostructure.Inrecrystallizedsample,α-fibertexturecomponentisweaklydetectedwhiletheothertexturecomponents,rotatedcubeandγ-fibercomponents,appearstoberelativelyunchanged.Noadditionaltexturecomponentsweredetectedbesidesthosetexturecomponentsobservedinthecoldrolledsamples.
简介:磁性的元素Fe,公司和Ni的线性热扩大(CLE)的系数用与MATLAB计算相结合的理论模型从试验性的信息被估计。模型参数能精确地被决定,并且估计的数据在对试验性的结果的好同意。便于评价,热扩大的理论被使用把CLE分开成它的无磁性、磁性的部件。对CLE的无磁性的贡献的计算基于MnBi/NdFeB混血儿的修改Grc性质结合的磁铁都逐渐地减少,当混合磁铁的密度几乎线性地改善时。在293-398的一个温度范围?K,混合磁铁的coercivity温度系数从0.59逐渐地改善?%比较。建模和频率与二低角落频率认为压力消除阀门是一个秒顺序系统是合理的试验性的结果表演。PID控制,死了的乐队赔偿控制和鷸?鷸??
简介:ThesolidsolubilityofCe、La、SmandNdinFeorNiatvarioustemperaturewasdeterminedbymeansofadiffusion-couplemethodwiththeaidofanelectronprobemicroanalyzer.Twomethods,namelyareamethodandwholerangemethod,wereproposedfordataprocessinginthepresentpaper.Theprincipleandre-latedproblemsintheexperimentaldeterminationofthesolidsolubilityofrare-earthelementsinFeorNibyuseoftheabovementionedmethodswerealsodiscussed.
简介:本文从观测常规产品Ni70Mn25Co5触媒合金片的表面缺陷入手,讨论了触媒片表观质量对金刚石合成效果的影响,从而也为触媒产品质量标准的制定提供了某些参考依据。
简介:Poroussiliconpillararray(PSPA)sampleswhichareidealsubstantialmaterialswithdominantelectronicandluminescencepropertieswerepreparedbysurfaceetchingmethod.ZnOnanorodswithorwithoutMndopinggrownuniformlyandalignedontoPSPAregardlessoflatticematchingshowvariousphotoluminescence(PL)properties.ThedopedMnionsinZnOnanorodsweredirectlyobservedbyX-rayphotoelectronspectroscopy(XPS),andZnOstructuresweredetectedbyX-raydiffraction(XRD).Asthedopingconcentrationincreases,XRDpeaksofZnOnanorodsshifttolowangle.TheinfluencesofdopingMnionsonluminescencepropertiesofZnOnanorodswereinvestigated.Exceptfortheultraviolet(UV)PLband,thebroadPLbandisobservedatvisibleregion.Thebandcouldbedividedintothreeseparatebands(orange,greenandred)byLorentziandeconvolution.TheintensityoforangePLbandfirstlyincreasesthendecreases,andthengetsthemaximumatthedopingMn-to-Znmolarratioof2.0:100.0whichisthemosteffectivedopingconcentration.ThegreenPLbandisattributedtozincvacancyofZnO,theorangePLbandtoMnionsrecombinationofitself,andtheredPLbandtooxygenvacancyofZnO,respectively.AstheMn-dopedZnOnanorodscouldemityellowgreenluminescenceexcitedbyUVradiation,anddopedMnionscouldimprovethecolorrenderingindexoftheluminescence,thenanorodscouldbeusedaspromisingwhite-lightemittersinthefuture.
简介:Al-5Ti-0.5C-8Sr(集体部分,%)主人合金用一个melt反应方法被准备。微观结构和主人合金的合成过程被光显微镜学,X光检查衍射,扫描电子显微镜学和X光检查调查精力散的光谱。结果证明主人合金由组成一(艾尔),TiAl3,TiC,Al4Sr和Al-Ti-Sr分阶段执行。主人合金的合成机制如下:TiAl3通过在K2TiF6和艾尔之间的反应被形成在基础材料的部分融化层融化在850个C粒子与同类地分布式的加强在超声的行动和一张契约下面被变成液体filler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brazi到达了37%?
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:ThemicrostructuresandVickershardnessatroomtemperatureofarc-meltingprocessedintermetallicsofMo5Si3-MoSi2hypoeutecticalloyandhypereutecticalloyannealedat1200℃fordifferenttimewereinvestigated.LamellarstructureconsistedofMo5Si3(D8m)phaseandMoSi2(C11b)phasewasobservedinallthealloys.ForMo5Si3-MoSi2hypoeutecticalloy,thelamellarstructurewasfoundonlyafterannealinganddevelopedwellwithfinespacingontheorderofhundrednanometersafterannealingat1200℃for48h.Butwhentheannealingtimewasupto96h,thewell-developedlamellarstructurewasdestroyed.ForMo5Si3-MoSi2hypereutecticalloy,thelamellarstructurewasfoundbothbeforeandafterannealing.Howeverthevolumefractionandspacingofthelamellarstructuredidnotchangesignificantlybeforeandafterannealing.Theeffectsoftheformation,developmentanddestructionoflamellarstructureonVickershardnessofalloyswerealsoinvestigated.WhenMo5Si3-MoSi2hypoeutecticalloyannealedat1200℃for48h,theVickershardnesswasimprovedabout19%comparedwiththatwithoutannealingandformationoflamellarstructure.ThehighestVickershardnessofMo5Si3-MoSi2hypereutecticwasincreasingabout18%whenannealingat1200℃for48h.
简介:
简介:ThehydrogenstoragepropertiesofTi1.2Fe+xCa(x=1%,3%and5%inmassfraction)alloyswasinvestigated.ResultsshowthatthemodifiedalloyscanbeactivatedwithoutanythermaltreatmentatroomtemperatureduetotheadditionofCaandexcessTiinthealloys.HydrogenstoragepropertiesofthesemodifiedalloysvarywithCaamountandreactiontemperature.Inaddition,theinfluencemechanismoftheadditionofCaandexcessiveTiontheactivationbehaviorandhydrogenstoragecapacityofthealloyswasdiscussed.
简介:TheeffectsofheattreatmentsonthephasetransformationbehaviorofTi49Ni49.5Fe1V0.5andTi48Ni48.5Fe1V2.5alloyswereinvestigated.TheresultsindicatethatthealloyssubjectedtodifferentheattreatmentshaveB2structureatroomtemperature.AllthespecimensexhibitatwostageB2→R→B190martensitictransformationoncooling,butaB190→B2one-stagereversemartensitictransformationonheatingexceptagedA1alloy,whichundergoesanabnormaltwo-stagetransformationuponheating.ThephasetransformationtemperaturesareaffectedbyheattreatmentsandVcontent,whichcanbeattributedtothevariationofthesecond-phaseparticlescontentinthematrix.
简介:采用纯Al片表面浸Zn后再电镀厚Cu层的方法制备Cu/Al层状复合材料。在473~673K温度范围内对该复合材料进行退火,研究退火过程中Cu/Al界面扩散与反应、界面金属间化合物(IMCs)层的长大动力学以及Cu/Al层状复合材料电阻率。结果表明,经过473K、360h的退火处理,未观察到Cu.AlIMCs层,显示Zn中间层能有效抑制Cu/Al界面扩散。可是,当复合材料经573K及以上温度退火时,Zn层中的Zn原子主要向Cu中扩散,从Al侧到Cu侧形成CuAl2/CuAl/Cu9Al4三层结构的反应产物。IMC层遵循扩散控制的生长动力学,Cu/Al复合材料的电阻率随退火温度及时间的增加而增大。
简介:通过第一性原理计算方法研究了Mg-Al-Ca-Sn合金中主要强化相Mg17Al12,Al2Ca,Mg2Sn和Mg2Ca的结构稳定性、电子结构、弹性常数和热力学性质。计算所得晶格常数与实验值及文献值吻合。合金形成热和结合能计算结果表明,Al2Ca具有最强的合金形成能力及结构稳定性。通过对这些化合物的态密度、Mulliken电子占据数、金属性和差分电荷密度计算分析了其结构稳定性的机制。通过计算Mg17Al12,Al2Ca,Mg2Sn和Mg2Ca的弹性常数,推导出了各相的体模量、剪切模量、杨氏模量和泊松比。热力学性质计算结果表明,Al2Ca和Mg2Sn的Gibbs自由能低于Mg17Al12,即Al2Ca,Mg2Sn的晶体结构稳定性优于Mg17Al12相。因此,通过添加Ca和Sn元素可以提高Mg-Al系合金的热力学稳定性。更多还原
简介:Thecorrosionbehaviorandanti-corrosionmechanismoftheZn-Ni-Al2O3compositecoatingwereinvestigatedbySEM,EDSandXPS.TheresultsindicatethatthecorrosiontypeoftheZn-Ni-Al2O3coatingsinneutral5wt.%NaClsolutionisuniformcorrosion.ThepresenceofcompactanduniformlydispersednanoaluminaparticlessubstantiallyinhibitsthecorrosionofZn-Ni-Al2O3compositecoatings.Intheinitialcorrosionstage,thecorrosiveproductsofZn-NimatrixformacompactZnCl2·4Zn(OH)2layer.Withthedevelopmentofcorrosion,somenanoaluminaparticlesareembeddedandformaNienrichmentlayer.InNienrichmentlayer,NipresentsasNiandNiO.