简介:双相不锈钢1Cr18Ni11Si4AlTi由前苏联研制,目前在我国某些特殊行业中有重要的作用。根据我国现有标准GJB2294—95和GB/T1220—92组织生产,发现按标准中现行成分设计、热处理制度生产的产品与标准要求的力学性能(屈服强度σ0.2)需达到的规定值存在较大差异,很难达到所需要的屈服强度。通过完善相关成分和工艺参数,获得了满意的金相组织和优良的综合力学性能。通过试验探讨了生产实际与标准中的部分规定存在的差距。
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简介:PrecipitationstudywascarriedoutinNi-35at.pctCralloybymeasuringelectricalresistivityatdifferentageingtemperaturesandlongageingtimes.Duringageing,itwasobservedthatelectricalresistivityinitiallyrosewithageingtimeandthenfellafterverylongageingataconstanttemperature.TheinitialincreaseinresistivityduringageingmaybeattributedtotheformationofGPzones/Cr-richprecipitatesatearlystagesbynucleationprocessanddecreaseinresistivity,andafterattainingamaximum,isduetothegrowthofprecipitateparticlesandsubsequentlybycoarseningoftheseprecipitates.TheresultsofelectricalresistivitymeasurementsduringageingwereconfirmedbyX-raydiffractionanalysisindicatingtheformationofaCr-richphaseandaCr3Ni2phaseintheNimatrix.
简介:1.IntroductionLightrareearthadditioncanremarkablyenhancetheservicelifeofFe-Cr-Alalloyforelectricalheatingelement,butitscontentinthealloymustbecontrolledbelowthelevelof0.1wt-%.Whenthecontentexceedsthat,theperformance
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简介:Si3N4/TiCnanocompositeceramicshavebeenfabricatedbyhotpressingtechniquewithAl2O3andY2O3asadditives.TheresultsshowedthatwelldispersedcompositepowderwascarriedoutbyaddingdispersantandadjustingpHvaluesofsuspensions.RemarkableincreaseinflexuralstrengthatroomtemperatureswasobtainedbyaddingnanoparticlesinSi3N4matrixwith10%(wtpct)ofnano-Si3N4and15%ofnano-TiC.Theflexuralstrength,fracturetoughnessandhardnesswere1025MPa,7.5MPa·1/2and15.6GPa,respectively.Themicrostructuresofmaterialswereanalyzedbyscanningelectronmicroscopy(SEM)andtransmissionelectronmicroscopy(TEM),whichindicatedthatTiCnanoparticlesdistributeinthematrixandatthegrainboundaries.Accordingtothefractureform,lowcontentsofnanoparticlescouldrefinematrixgrainsandleadtothecrackdeflectionaswellascrackpinning.Themultiplexmicrostructurewasformedbymixingnano-Si3N4particles.Thecracktrajectoriesexhibitedcrackdeflection,rod-likegrainbridgingandpull-out.
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简介:(Ni0.81Fe0.19)0.66Cr0.34hasahighresistivityandacrystalstructureclosetothatofNi0.81Fe0.19.TheelectricalandX-raydiffractionmeasurementsprovethatathinNiFeCrseedlayerinducesawell(111)-orientedNi0.81Fe0.19film.Post-annealingtreatmentimprovesthemagneticpropertiesof(Ni0.81Fe0.19)0.66Cr0.34(45A)/Ni0.81Fe0.19(150A)/Ta(55A)thinfilmpreparedunderadepositionfield,whereastheinter-diffu-sionofNiFe/Tadeterioratesthemagnetoresistancepropertiesofthefilm.
简介:Inthispaper,polycrystallinesiliconfilmsweredepositedbyelectroncyclotronresonanceplasma-enhancedchemicalvapordeposition(ECR-PECVD)usingSiH_4/ArandSiH_4/H_2gaseousmixture.EffectsofargonflowrateonthedepositionefficiencyandthefilmpropertywereinvestigatedbycomparingwithH_2.TheresultsindicatedthatthedepositionrateofusingArasdischargegaswas1.5-2timeshigherthanthatofusingH_2,whilethepreferredorientationsandthegrainsizesofthefilmswereanalogous.FilmcrystallinityincreasedwiththeincreaseofArflowrate.OptimizedflowratioofSiH_4toArwasobtainedasF(SiH_4):F(Ar)=10:70forthehighestdepositionrate.
简介:Si_3N_4-Si_2N_2Ocomposites被液相sintering(LPS)与非结晶的缩放nano的氮化矽粉末制作。Si_2N_2O阶段被in-situreaction2Si_3N_4(s)+1.5O_2(g)=3Si_2N_2O+N_2(g)产生直到在体积的60percent的Si_2N_2O阶段的内容在1650t的sintering温度被获得并且当sintering温度增加了或减少时,减少了,显示反应是可逆的。集体损失,相对密度和平均谷物尺寸与增加sintering温度增加了。当sintering温度在1700degC下面时,Theaverage谷物尺寸是不到500nm。Thesintering过程包含复杂结晶化和阶段转变:非结晶的氮化矽->equiaxialalpha-Si_3N_4->equiaxial->Si_3N_4->杆--相似Si_2N_2O->像针的beta-Si_3N_4。小回合--塑造的beta-Si_3N_4粒子在Si_2N_2O谷物被骗诱,界定差错的高密度位于在1650degC的sintering温度的Si_2N_2O谷物的中间。坚韧在1600degCto7.2MPa从3.5Mpa中心点m~(1/2)增加了在1800degC的中心点m~(1/2)。坚硬在1600degC象21.5GPa(Vickers)一样高。
简介:Intrinsiccarrierconcentration(ni)isoneofthemostimportantphysicalparametersforunderstandingthephysicsofstrainedSiandSi1-xGexmaterialsaswellasforevaluatingtheelectricalpropertiesofSi-basedstraineddevices.Uptonow,thereportonquantitativeresultsofintrinsiccarrierconcentrationinstrainedSiandSi1-xGexmaterialshasbeenstilllacking.Inthispaper,byanalyzingthebandstructureofstrainedSiandSi1-xGexmaterials,boththeeffectivedensitiesofthestatenearthetopofvalencebandandthebottomofconductionband(NcandNv)at218,330and393KandtheintrinsiccarrierconcentrationrelatedtoGefraction(x)at300KweresystematicallystudiedwithintheframeworkofKPtheoryandsemiconductorphysics.ItisfoundthattheintrinsiccarrierconcentrationinstrainedSi(001)andSi1-xGex(001)and(101)materialsat300KincreasessignificantlywithincreasingGefraction(x),whichprovidesvaluablereferencestounderstandtheSibasedstraineddevicephysicsanddesign.
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简介:采用HSiCl3—NH3—N2(稀释气体)体系在石英陶瓷基板上通过低压化学气相沉积(LPCVD)法沉积出了Si3N4涂层,研究了工艺条件对涂层沉积速率的影响。结果表明,在没有稀释气体的情况下,随着沉积温度升高,Si3N4涂层的沉积速率逐渐增加,在850℃附近达到最大值,随着反应温度的进一步升高,涂层沉积速率下降。当存在稀释气体时,在所选温度范围内随着沉积温度的升高,Si3N4涂层的沉积速率一直增大,反应的表观活化能约为222kJ/mol。随着原料中NH3/HSiCl3流量比值的增大,Si3N4涂层的沉积速率逐渐增加,随后稳定,但稍有下降趋势。在所选稀释气体流量范围内,Si3N4涂层的沉积速率随着稀释气体流量的增加而增大。
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