简介：Precipitationstrengtheningaswellassolutionstrengtheningiskeymechanismforheatresistantsteels.Itisveryimportanttocharacterizetheprecipitatesin9%Crferriteheatresistantsteels,especiallytoshowthenanometer-sizedparticles.Bytransmissionelectronicmicroscopeattachedwithanenergydispersivespectrometeraswellasopticalmicroscope,scanningelectronicmicroscope,themicrostructureandchemicalcompositionofprecipitatesina9%Crheatresistantsteelafterdifferentheattreatmentswereinvestigated.ItwasfoundthatthemicrostructureofnormalizedsamplewasmartensitewithfineNbCandFe3C.Themicrostructureoftemperedsampleistemperedmartensite,andtheremainlyweretwotypesofprecipitates,M23C6withthesizerangeof50-300nmandMXwiththesizeof10-100nm.SuperfineM23C6precipitatedpreferablyonpriorausteniticgrainboundariesandmartensiticlathboundaries,whilenanometer-sizedMXprecipitatesweredistributedrandomly.Aftershort-termcreep,Lavesphaseformedalonggrainboundariesofthe9%Crsteel,andM23C6andMXprecipitateswerefoundtobecomecoarser.Moreinformationaboutprecipitatesinthe9%Crsteelhadbeenexhibitedbyatomicforcemicroscopy.Thereby,distribution,sizeandshapeoftheprecipitatesaswellastheircompositionsandstructureswererevealed.

简介：Niobium,asthemosteffectivesecond-phaseformingelement,wasaddedintheFe-Cr13-C-Nhard-facingalloytogetcarbonitrideprecipitates.Morphologyandcompositionofcarbonitrideinthehardfacingalloywerestudiedbyopticalmicroscopy,scanningelectronmicroscopy,andelectronprobemicroanalyzer.Thether-modynamicsandtheeffectonthematrixoftheformationofcarbonitridewerealsodiscussed.ItwasfoundthatniobiumcarbonitridesarecomplexNb(C,N)precipitatedistributedongrainboundaryandmatrixofthehardfacingalloy.Underas-weldedcondition,primarycarbonitrideparticleswerereadilyprecipitatedfromthehardfacingalloywithlargesizeandmorphologyastheywereformedalreadyduringsolidification.Underheattreatmentcondition,alargenumberofsecondarycarbonitridescanpre-cipitateoutwithveryfinesizeandmakeagreatsecondaryhardeningeffectonthematrix.Asaresult,additionofniobiuminthehardfacingalloycanpreventtheformationofchromium-richphaseongrainboundariesandinter-granularchromiumdepletion.

简介：ThesecondaryhardeningreactionisaccompaniedwithprecipitationoffinecarbidesinhighCoNiultrahighstrengthsteel.Thecrystalstructureoftheprecipitatingcarbidesisunambiguouslydeterminedbymicrobeamdiffractionintransmissionelectronmicroscopy.Itisidentifiedthattheneedle-shapedcarbidesareM2Cwithahexagonalstructure.TheconcentrationofsubstitutionalalloyingelementsinthecarbidesquantifiedbyenergydispersiveX-rayspectroscopy(EDS)alsosupportstheresultabove.ThespatialstructureofM2CisidenticalwithL'3type.Metalatomsareinaclosepackedhexagonalstructure,thecarbonatomspartlydistributewithrandomintheoctahedralintersticesandthefillingprobabilityislessthan1/2.Particularattentionwaspaidtotherelationshipofneedle-shapedcarbides/ferritematrixatsecondaryhardeningpeaktemperedat482℃for5h.Observationbyhighresolutiontransmissionelectronmicroscopy(HRTEM)confirmsthatcarbideswithblack-whitecontrastarefullycoherentwithferriteandhaveindividualcrystalstructure,andthecoarsenedcarbideswithmoirefringearepartiallycoherentwithmatrix.TheorientationrelationshipbetweenM2CandferritematrixisdirectlyobservedandidentifiedwiththewellestablishedP-Srelationship[001]α//[111]c.

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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。