简介：Theadvancedfabricationofin-situdendrite/metallicglassmatrix（MGM）compositesisreviewed.Herein,thesemisolidprocessingandBridgmansolidificationaretwomethods,whichcanmakethedendriteshomogeneouslydispersedwithinthemetallicglassmatrix.Uponquasi-staticcompressiveloadingatroomtemperature,almostallthein-situcompositesexhibitimprovedplasticity,duetotheeffectiveblocktothefastpropagationofshearbands.Uponquasi-statictensileloadingatroomtemperature,althoughthecompositespossesstensileductility,theinhomogeneousdeformationandassociatedsofteningdominates.Highvolume-fractioneddendritesandnetworkstructuresmakein-situcompositesdistinguishinglyplasticupondynamiccompression.In-situcompositeexhibitshightensilestrengthandsoftening（necking）inthesupercooledliquidregion,sincethepresenceofhighvolume-fractioneddendriteslowerstherheologyoftheviscousglassmatrixathightemperatures.Atcryogenictemperatures,adistinguishingly-increasedmaximumstrengthisavailable;however,aductile-to-brittletransitionseemstobepresentbyloweringthetemperature.Besides,improvedtension—tensionfatiguelimitof473MPaandfour-point-bendingfatiguelimitof567MPaaregainedforZr58.5Ti14.3Nb5.2Cu6.1Ni4.9Be11.0MGMcomposites.Highvolume-fractiondendriteswithintheglassmatrixinduceincreasedeffectivenessonthebluntingandpropagatingresistanceofthefatigue-cracktip.Thefracturetoughnessofin-situcompositesiscomparabletothoseofthetougheststeelsandcrystallineTialloys.Duringsteady-statecrack-growth,theconfinementofdamagebyin-situdendritesresultsinenhancementofthetoughness.

简介：Basedonthethermodynamictheory,anorthotropicdamageconstitutivemodelwasdevelopedtodescribethenonlinearmechanicalbehaviorofC/SiCcomposites.Thediferentnonlinearkinematicandisotropichardeningfunctionswereadoptedtodescribeaccuratelythedamageevolutionprocesses.Thedamagevariablesweredefinedwiththedamagedmodulusandtheinitialundamagedmodulusonenergyequivalenceprinciple.Theinitialorthotropyanddamagecouplingwerepresentedinthedamageyieldfunction.Tensileandin-planeshearloadingandunloadingtestswereperformed,andagoodagreementbetweenthemodelandtheexperimentalresultswasachieved.

简介：Theresultsofatheoreticalstudyontheinfluenceofstrengthofinterphaseboundariesinmetal—ceramiccompositeonmacroscopicalcharacteristicsofcompositeresponsesuchasstrength,deformationcapacity,fractureenergyandfracturepatternarepresented.Thestudywasconductedbymeansofcomputer-aidedsimulationbymeansofmovablecellularautomatonmethodtakingaccountofadeveloped'mesoscopical'structuralmodelofparticle-reinforcedcomposite.Thestrengthofinterphaseboundariesisfoundtobeakeystructuralfactordeterminingnotonlythestrengthpropertiesofmetal—ceramiccomposite,butalsothepatternandrateoffracture.Theprinciplesforachievementofthehigh-strengthvaluesofparticle/binderinterfacesinthemetal—ceramiccompositionduetotheformationofthewidetransitionzones(areasofvariablechemicalcomposition)attheinterphaseboundariesarediscussed.Simulationresultsconfirmthatsuchtransitionzonesprovideachangeinfracturemechanismandmaketheachievementofahigh-strengthandahighdeformationcapacityofmetal—ceramiccompositepossible.

简介：Milledformofmesophasepitch-basedgraphitefiberswerecoatedwithatitaniumlayerusingchemicalvapordepositiontechniqueandTi-coatedgraphitefiber/Cucompositeswerefabricatedbyhot-pressingsintering.ThecompositeswerecharacterizedwithX-raydiffraction,scanning/transmissionelectronmicroscopies,andbymea-suringthermalproperties,includingthermalconductivityandcoefficientofthermalexpansion(CTE).Theresultsshowthatthemilledfibersarepreferentiallyorientedinaplaneperpendiculartothepressingdirection,leadingtoanisotropicthermalpropertiesofthecomposites.TheTicoatingreactedwithgraphitefiberandformedacontinuousanduniformTiClayer.Thiscarbidelayerestablishesagoodmetallurgicalinterfacialbondinginthecomposites,whichcanimprovethethermalpropertieseffectively.Whenthefibercontentrangesfrom35vol%to50vol%,thein-planethermalconductivitiesofthecompositesincreasefrom383to407Wá(máK)-1,andthein-planeCTEsdecreasefrom9.5910-6to6.3910-6K-1.

简介：Objectives:Polymerizationshrinkageofdentalcompositesremainsamajorconcerninrestorativedentistrybecauseitcanleadtomicro-crackingofthetoothanddebondingatthetooth-restorationinterface.Theaimofthisstudywastomeasurethefull-fieldpolymerizationshrinkageofdentalcompositesusingtheopticaldigitalimagecorrelation(DIC)methodandtoevaluatehowthemeasurementisinfluencedbythefactorsinexperimentsetupandimageanalysis.Methods:Fourcommercialdentalcomposites,PremiseDentine,Z100,Z250andTetricEvoCeram,weretested.Compositewasfirstplacedintoaslotmouldtoformabarspecimenwithrectangular-sectionof4mmmm,followedbythesurfacepaintingtocreateirregularspeckles.Curingwasthenappliedatoneendofthespecimenwhiletheotherpartwerecoveredagainstcuringlightforsimulatingtheclinicalcuringconditionofcompositeindentalcavity.Thepaintedsurfacewasrecordedbyacharge-coupleddevice(CCD)camerabeforeandaftercuring.Subsequently,thevolumetricshrinkageofthespecimenwascalculatedwithspecialistDICsoftwarebasedonimagecrosscorrelation.Inaddition,afewfactorsthatmayinfluencethemeasuringaccuracy,includingthesubsetwindowsize,specklesize,illuminationlightandspecimenlength,werealsoevaluated.Results:ThevolumetricshrinkageofthespecimengenerallydecreaseswithincreasingdistancefromtheirradiatedsurfacewithaconspicuousexceptionbeingthecompositePremiseDentineasitsmaximumshrinkageoccurredatasubsurfacedistanceofabout1mminsteadoftheirradiatedsurface.Z100hadthegreatestmaximumshrinkagestrain,followedbyZ250,TetricEvoCeramandthenPremiseDentine.Largersubsetwindowsizemadetheshrinkagestraincontoursmoother.Butthecostwasthatsomedetailsintheheterogeneityofthematerialwerelost.Verysmallsubsetwindowsizeresultedinalotofnoiseinthedata,makingitdifficulttodiscernthegeneralpatterninthestraindistribution.Speckle

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简介：Inthisstudy,Almatrixcompositesreinforcedby7.5and15vol.%B4CparticlesandalsomonolithicAl（AlwithouttheB4Cparticles）wereproducedbywetattritionmillingandsubsequenthotforwardextrusionprocesses.Themicrostructureofthecomposites,evaluatedbyscanningelectronmicroscopy（SEM）,showedthattheB4CparticleswereproperlydistributedintheAlmatrix.MechanicalpropertiesoftheAI/B4CcompositesandmonolithicAlwereinvestigatedbytensile,wearandhardnesstests.TheresultsrevealedthatwithincreasingcontentofB4Cparticles,thetensilestrengthandmicrohardnessofcompositesincreasedbuttheelongationdecreased.Inaddition,thetensilestrengthandmicrohardnessofcompositesampleswerehigherthanthoseofmonolithicAl.ThedensitymeasurementsrevealedthatthedensityofcompositesdecreasedwithincreasingcontentoftheB4Cparticles.

简介：Althoughin-situgrowingcarbonnanotubes(CNTs)oncarbonfiberscouldgreatlyincreasethematrix-dominatedmechanicalpropertiesofcarbon/carboncomposites(C/Cs),italwaysdecreasedthetensilestrengthofcarbonfibers.Inthiswork,CNTswereintroducedintounidirectionalcarbonfiber(CF)preformsbyelectrophoreticdeposition(EPD)andtheywereusedtoreinforceC/Cs.EffectsofthecontentofCNTsintroducedbyEPDontensilepropertyofunidirectionalC/Cswereinvestigated.ResultsdemonstratedthatEPDcouldbeusedasasimpleandefficientmethodtofabricatecarbonnanotubereinforcedC/Cs(CNT—C/Cs)withexcellenttensilestrength,whichpaysameaningfulwaytomaximizetheglobalperformanceofCNT—C/Cs.

简介：Tomeettheincreasingdemandforadvancedmaterialscapableofoperationover2000℃forfuturethermalprotectionsystemsapplication,C/C—ZrC—SiCcompositeswerefabricatedbyreactivemeltinfiltration(RMI)withZr,Simixedpowdersasrawmaterials.ThestructuralevolutionandformationmechanismoftheC/C—ZrC-SiCcompositeswerediscussed,andthemechanicalpropertyoftheas-preparedmaterialwasinvestigatedbycompressiontest.TheresultsshowedthataftertheRMIprocess,aspecialstructurewithZrC-SiCmulti-coatingasouterlayerandZrC-SiC-PyCceramicsasinnermatrixwasformed.ZrCandSiCrichareaswereformedinthecompositesandonthecoatingsurfaceduetotheformationofZr-SiintermetalliccompoundsintheRMIprocess.MechanicaltestsshowedthattheaveragecompressionstrengthoftheC/C-ZrC-SiCcompositeswas133.86MPa,andthecarbonfibersinthecompositeswerenotseriouslydamagedaftertheRMIprocess.