简介：ＦｒａｃｔｕｒｅＣｈａｒａｃｔｅｒｉｓｔｉｃｓｏｆＳｉＣ（ｐ）／ＡｌＣｏｍｐｏｓｉｔｅｓＧｕＨｏｎｇｗｅｉ；ＣａｏＬｉ；ＹｕａｎＧｕａｎｓｅｎ；ＬｉｕＡｎｓｈｅｎｇ；ＷｕＺｉｑｉｎａｎｄＣｈｅｎＬａｎｆｅｎｇ（古宏伟），（曹利），（袁冠森），（刘安生...

简介：ThefracturebehaviorofSiCp/A356compositeatroomandhightemperatureswasstudied.Undertensilestressconditionatroomtemperature,thefractureismostlyacombinationofthebrittlefractureofSiCparticlesandductilefractureofA356matrix.Asthetensiletemperatureincreases,thecompositechangesthemainfracturebehaviortotheseparationfractureofthebondingsurfacebetweenSiCparticlesandA356matrix.Whenthetensiletemperaturereaches573K,thefracturebehaviorofthecompositesisalmostthewholeseparationfractureofthebondingsurface,whichisthemainstrengtheningmechanismathightemperature.Underthecyclestressconditionatroomandhightemperatures,themainfracturebehaviorofthecompositesisalwaysacombinationofthebrittlefractureofSiCparticlesandductilefractureofA356matrix.However,underthecyclestressathightemperature,cyclebehaviorofthecompositeschangesfromcyclehardeningatroomtemperaturetothecyclesofteningathightemperature.

简介：Themultilayered7XXXseriesaluminumalloywasimpactedby7.62mmogivalprojectilesatvelocitiesrangingfrom787to851m·s~(-1).Thedeformedmicrostructureundervariousimpactingvelocitiesandfracturesurfacesofdifferentsectionswereinvestigatedatdifferentphysicalscalestodeterminetheprocessoffailure.Opticalmicroscopy(OM),electronback-scattereddiffraction(EBSD)andscanningelectronmicroscopy(SEM)wereusedintheinvestigation.Theresultsshowthatcraterisconstrainedinthe7B52frontlayerandtwotypesofadiabaticshearbandswhicharetransformedbandsanddeformedbandsanddifferenttypesofcracksareobserved.Spallfractureisthesignificantfailuremodeof7B52frontlayer,andtheresultingdelaminationleadstothepresenceofbendingtensilefractureinsteadoftheshearplugging.Theductile7A01layerbluntsanddeflectsthespallcracktips,preventingthetargetsfromfullspall,andinducesaconstraintof7A52rearlayer.Theleveloftheconstraintdeterminesdifferentfracturemodesof7A52layer,accountingfortheasymmetryofdamage.

简介：Mechanicalpropertiesofgalvannealed(GA)steelsheetusedforautomotiveexposedpanelandpredictedfailurephenomenonofitscoatinglayerwereevaluatedusingfiniteelementmethod.V-bendingtestwasperformedtounderstandbetterthefractureofcoatinglayerofGAsteelsheetduringplasticdeformation.Yieldstrengthofthecoatinglayerwascalculatedbyusingarelativedifferencebetweenhardnessofcoatinglayermeasuredfromthenano-indentationtestandthatofsubstrate.Tomeasureshearingstrengthattheinterfacebetweensubstrateandcoatinglayer,shearingtestwithtwospecimensattachedbyanadhesivewascarriedout.Usingthemechanicalpropertiesmeasured,aseriesoffiniteelementanalysescoupledwithafailuremodelwasperformed.Resultsrevealthatthefractureofcoatinglayeroccursinanirregularmannerattheregionwherecompressivedeformationisdominant.Meanwhile,aseriesofverticalcracksperpendiculartomaterialsurfaceareobservedatthetensilestressed-region.Itisfoundthat0.26-0.28oflocalequivalentplasticstrainexistsatthecoatingandsubstrateatthebeginningoffailure.Thefractureofcoatinglayerdependsonductilityofthecoatinglayerconsiderablyaswell.

简介：在典型周期的装载下面的near-alpha钛合金的疲劳行为上的试验性的调查被执行模仿装载在引擎片上使用的状态的服务。低周期的疲劳(LCF)测试的轴的控制压力的紧张紧张在最大的压力和压力比率的一个范围上被执行。旋转弯曲测试用一个装载步的过程被进行揭示高周期的疲劳(HCF)限制压力。周期的弄软效果在这材料被观察，并且紧张ratcheting在900装载的最大的LCF显然发生?MPa。LCF抵抗被发现依赖于装载的最大值和压力比率。为1的HCF限制压力?NA被货车derWaals力量鰨?鰨主要地管理？？

简介：AnexperimentalMg97Zn1Y2(molarfraction,%)alloywasproducedbyrollingtheas-castalloy.Themicrostructureofthealloyiscomposedoftheα-Mg(alsomarkedas2H-Mgwithreferencetolong-periodstackingstructureaccordingtohexagonalclosepackedstructure)andlong-periodstacking(LPS)phase.TensiletestsofMg97Zn1Y2alloyincomparisonwithpureMgwereconducted.Thefracturemorphologiesofthetensilespecimenswerecharacterizedandthemicrostructuresnearfracturesurfacewereobserved.TheresultsshowthattherolledMg97Zn1Y2alloyshowsamixedfracturemodeincludingdimplesindicatingaductilefracturepatternandasmallfractionofcleavageplanesindicatingabrittlefracturepattern,whichisdifferentfromthesinglebrittlefractureoftheas-castalloy.Inaddition,theplasticdeformationismainlyfromdislocationsinducedstrainwithsmallstrengtheningeffectduringplasticdeformationintheas-castMg97Zn1Y2alloy,andthestrainhardeningrateissimilartothatoftheas-castpuremagnesium.ThedeformationmechanismofMg97Zn1Y2alloyisdifferentfromthatofthepuremagnesiumaccordingtoametallographicalobservationthatwhethertwinsarefoundornot.ThestrengtheningeffecthardlyexistsintherolledMg97Zn1Y2alloyunderthesamedislocationsinducedstrain,whichisdifferentfromthatoftheas-castalloywithmoderatestrengtheningeffect.

简介：Inthepresentwork,anovelhybridcompositecomposedofTi-aluminidemulti-layeredpartandcontin-uous-SiCf-reinforcedTi-matrixpartusingavacuumhotpressing/hotisostaticpressure（VHP/HIP）sinteringprocesswassynthesized.Then,thedamagetolerancebehaviorofthishybridcompositewasstudiedbytensiletestsandinsituscanningelectronmicroscopy（SEM）three-pointbendingtests.Theresultsindicatethatthemechanicalpropertiesandcrackpropagationofthehybridcompositearestronglyinfluencedbytheextrinsictoughnessmecha-nism.Indetail,thecrackdeflectionofmulti-layeredcompositeandstrengtheningeffectofSiCf-reinforcedmatrixcompositeareobservedinthehybridcomposite.Owingtothestrengtheningeffectofcontinuous-SiCrre-inforcedTi-matrixpart,thetensilestrengthofhybridcompositeismuchhigherthanthatofneatTi-aluminidemulti-layeredcomposite.Furthermore,itisfoundthattheoptimaldamagetoleranceabilityisoptimizedwhenthenotchpositionislocatedattheTi-aluminidemulti-layeredpartduetothecrackdeflectionofmulti-layeredstructure.