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简介:Defectsofpolymer-derivedSi-C-OfiberswereintensivelystudiedbytheSEMandTEMtechniquesandtheiroriginationswerealsodiscussedonthebasisoffactorsexperiments.Thedefectswerefoundmainlyintheformofstrumaes,pitsandsplitsonsurfacesaswellasmicroflawnetworks,porosityclustersandinclusionsinthebulk.Factorsexperimentsrevealthatanonuniformoraninsufficientcuringwouldresultinlarger-sizedstru-maesorinteriormicroflaws.Gasevolutionratesduetodifferentfiringrateshaveagreatinfluenceontheformationofinternalmicrofiawsorporosityclustersandsomeoxidation-inducedpitsorsplitsmaybeformedonsurfacesbe-causeoratraceofoxygenorwatervaporaccumulatedfromtheflowinginertatmosphereduringpyrolysis.
简介:Usingaspecialconstantdeflectiondevice,thechangesindislocationconfigurationaheadofaloadedcracktipfor60Fe40Nialloy,beforeandaftermagnetizationinamagneticfield,havebeenstudiedinTEM.Theresultsshowedthatthemagnetizationfor60Fe40Nialloycouldenhancedislocationemission,multiplicationandmotion.Also,themechanicalpropertiesof60Fe40Nialloy,inairandinthemagneticfieldrespectively,havebeeninvestigatedusingtheslowstrainratetension.Andtheresultsindicatedthatmagnetizationcouldmaketheyieldstrengthcorrespondingtodecreaseby26percent,butdidnotinfluencetheultimatetensilestrengthandthefracturestrain,whichshowedthatmagnetizationcouldenhanceplasticdeformation.
简介:Basedontheclassicdiffusioncontrollednucleationandgrowththeory,thesympatheticnucleationledgewisegrowthmechanismofbainitewasstudiedtheoreticallyforIowcarbonFe-Calloys.Therationalityoftheoccurrenceofsympatheticnucleationontheterracesofledgescompetingwithlateralledgegrowthandothersitesnucleationwasdemonstratedbythepresentworkquantitatively.ThecalculationsindicatedthatIowreactiontemperaturesandhighcarbonconcentrationsmayfavorthesympatheticnucleation,thusaccountingfortheformationofmultilayerstructuresofbainite.
简介:Sodiumparanitrophenolatedihydrate(NPNa·2H2O)isanexcellentsemiorganicnonlinearoptical(NLO)material,crystallizesbothinwaterandmethanolwithhighdegreeoftransparency.Goodopticalqualitysinglecrystalsofdimensionupto18mmx6mmx3mmareobtainedbyisothermalsolventevaporationtechnique.Thesolubilityofthecrystalindifferentsolventswasmeasuredgravimetrically.ThesinglecrystalsofNPNa·2H2Oshowvariationinphysicalpropertiesandgrowthrateindifferentsolvents.Methanolorethanolsolutionyieldscrystalsofbipyramidalshapewithclearmorphology.However,methanolgrowncrystalisexhibitingimprovedhardnessparametersandpossessesexcellentthermalstabilityascomparedtowatergrowncrystals.TheeffectsofsolventonhardnessparameteralongwiththermalandopticalpropertiesofNPNa·2H2Owasrevealedinthispaper.