简介:BasedontheMiedemamodelandExtendedMiedematheory,theformationenergiesofdifferentsolutecomponentsinEr-XbinarysystemandAl-Er-Xternarysystemswerecalculated.TheresultsshowthatthevariationoferbiumcontenthaslittleinfluenceonthechancerateoftheformationAl-ErcompoundintheAl-Mg-Mn-Zr-Ersystem.ThecalculatedformationenergiesintheEr-XbinarysystemandAl-Er-XternarysystemsindicatethatAl3Erphasecantakepriorityofdepositing,Al-Er-Zrternarycompoundsmayalsofoundwhichagreeswiththeexperimentalresultsinreferences.TheconsistencyofcalculationandexperimentprovesthattheintermetalliccompoundsintheAl-Mg-Mn-Zr-ErsystemcanbepredicteddirectlybycalculatingtheformationenergiesofthereactionsinEr-XbinarysystemandAl-Er-XternarysystemswiththeMiedemamodelandExtendedMiedematheory.
简介:通过射线照相检测对TC4钛合金铸件内部常见缺陷及其在热等静压前后的演变进行分析,结果表明:TC4钛合金铸件内部大部分闭合孔洞类缺陷经热等静压均可消除,内部缺陷底片上显示消失;少量的夹杂类和非闭合孔洞类缺陷未压合,在底片上与热等静压前缺陷显示基本一致;个别缩孔缺陷部分压合或表面压陷,极少量的大尺寸缩孔缺陷压缩变形为线性缺陷,在底片上缺陷显示形态发生变化。由于线性缺陷的结构特征在射线照相检测时易导致影像对比度下降,进而影响缺陷的检出率,因此应在热等静压前对易产生缩孔部位进行射线照相检测并将大尺寸缩孔清除补焊,避免热等静压后缩孔压缩变形造成缺陷漏检。
简介:Inthisinvestigation,themechanicalpropertiesandlow-temperaturefracturetoughnessofAPI5LX65offshorepipelineweldedjointswerestudied.StructureIntegrityAssessmentProcedure(SINTAP)-FailureAssessmentDiagram(FAD)methodwasappliedtothepipestructurewithsurfaceflawattheweldtoe.AccordingtotheISOstandardBS7448,theCTODfracturetoughnessoftheweldedjointswasdeterminedatthetemperatureof0℃.Fortheheat-affectedzone(HAZ)specimens,post-testmetallographicanalysiswasperformedtoverifythatthetipofthecrackwaslocatedinthecoarsecrystalzoneinordertoconfirmthevalidityoftheaboveresults.Thefailurelinesofanalysislevel1and3ofweldmetalwerederivedfromtheresultsofthemechanicalpropertytest.Theassessmentwasperformed,consideringthemaximumlaystress,residualstressconservativelyassumedtobeuniformtensilestress,andminimumCTODvalue.Theresultsoftheassessmentshowedthatpipelinestructurewithasurfaceflaw(theheightandlengtharerespectively2.2mmand5mm)attheweldtoeissafe.ThisstudylaysthefoundationofapplicationofSINTAPtopipelinestructureassessment.
简介:X-rayDouble-crystalDiffractometerwithHorizontalSlitsandItsApplicationsXuJingyangandZhuNanchang徐景阳,朱南昌(ShanghaiInstituleofMeta...
简介:MgTixNi(x=0,0.1,and0.2)alloysweresuccessfullypreparedbymechanicalalloying(MA),andtheinfluenceofmillingtimeontheelectrochemicalcharacteristicsoftheelectrodeswasdiscussed.MgTixNialloysafter90hmillingdisplayedthebestelectrochemicalperformance.TheX-raydiffractionpatternsshowedthatthealloyball-milledfor90hwasamorphouswithawideneddiffractionpeak.Thecharge-dischargetestsindicatedthatthesealloyshadgoodelectrochemicalactivationproperties,andtheMgTi0.2Nialloyelectrodeexhibitedthebestcycleperformance.TheinitialdischargecapacityoftheMgTi0.2Nialloyreachedupto401.1mAh·g-1,andtheretentionrateofcapacitywas31.0%after30cycles,muchhigherthanthatofMgNi(17.3%).TheTafelpolarizationcurvesrevealedthatTiadditioncouldenhancetheanticorrosionperformanceofthesealloysinalkalisolution,whichwasresponsiblefortheamelioratedcyclicstabilityofthesealloyelectrodes.
简介:X-raydiffraction(XRD)anddifferentialscanningcalorimetry(DSC)wereusedtoinvestigatethecrystallizationprocessofamorphousAl90TMxCe10-x(atomfractionin%;TM=FeorNi;x=3,5)alloys.AgingeffectswereexaminedbyX-raydiffraction.ThestructurecorrespondingtotheprepeakfortheamorphousAl90Fe5Ce5alloyismorestablethantheamorphousmatrix,butitisnotstableforamorphousAl90Ni5Ce5alloyduringthefirstcrystallizationstageandevendecomposesatroomtemperature.AlthoughbothAl-NiandAl-Fehavestrongchemicalbonding,thecrystallizationonsettemperatureofamorphousAl-Fe-CealloysismuchhigherthanthatofamorphousAl-Ni-Cealloys,whichislikelycausedbythedifferentstabilityofthestructurecorrespondingtotheprepeak.ThecrystallizationonsettemperatureincreasesasCe/NiratioincreasesinamorphousAl90NixCe10-xalloys,whereasitdecreasesasCe/FeratioincreasesinamorphousAl90FexCe10-xalloys.AbetteratomicpackingproducesasCecontentincreasesbecauseofthesizemismatchinAlNi-CesystemsandasFecontentincreasesbecauseoftheincreasingFecentralstructuralunits.