简介:Solidificationstructurevariationofsinglephasealloywithundercoolingpriortonucleationhasbeenwidelystudied.Theprogress,especiallyduringthelastdecade,isreviewedsoastogiveacomprehensiveknowledgeforit,inwhichtheemphasesarelaidonthestructureevolutionmechanismandthepotentialapplication.Lastly,thefutureinterestingsubjectsarepresented.
简介:DensityofmoltenNiandNi-Walloyswasmeasuredinthetemperaturerangeof1773~1873Kwithasessiledropmethod.ThedensityofmoltenNiandNi-Walloystrendstodecreasewithincreasingtemperature.ThedensityandmolarvolumeofthealloystrendtoincreasewithincreasingWconcentrationinthealloys.ThecalculationresultshowsanidealmixingofNi-Walloys.
简介:1.IntroductionLightrareearthadditioncanremarkablyenhancetheservicelifeofFe-Cr-Alalloyforelectricalheatingelement,butitscontentinthealloymustbecontrolledbelowthelevelof0.1wt-%.Whenthecontentexceedsthat,theperformance
简介:Theinfluenceofthevolumefractionoftemperedmartensiteonmagnetomechanicaldampingoftheferriticmatrixindual-phasealloyswasstudied.Theexperimentalresultsshowedthat(1)dual-phasedampingalloyisofgoodcombinationofstrengthandtoughness:(2)gooddampingca-pacity(Q-1≥5.0×10-3)canbeobtainedindual-phasealloysonlywhenthevolumefractionoftemperedmartensitewascontrolledproperly.Theeffectofmartensiteonmagnetomechanicaldamp-ingoftheferriticmatrixwasanalysed.Thedampingcapacityofdual-phasealloyswasrelatedtothevolumefractionVmoftemperedmartensitebyQ-1=Q-1(1-Vm/1+BVm)atsmallvibrationstrainamplitudesεA≤5.0×10-6.
简介:
简介:RapidsolidificationofCu-Pbmonotecticalloyshasbeenaccomplishedduringfreefallina3mdroptube.BothmacrosegregatedanduniformlydispersedstructuresareobservedinCu-40wtpctPballoydroplets,whereasdropletsofcompositionCu-64wtpctPbexhibitonlymacrosegregationmorphologies.Themicrostructuresarestronglydependentondropletsize.Thehigherundercoolingtendstofacilitateliquidphaseseparationandresultsinmoreextensivemacrosegregationinsmallerdroplets.ThereexistsapronouncedtendencyforthePb-richliquidtooccupythesurfaceofthedropletsofbothcompositions,resultingfromthequitelowersurfacetensionofthePb-richphaseandcausingaPb-richlayeratthesurfaceofthesolidifieddroplet.ThenucleationofmonotecticcellsintheCu-40wtpctPbdropletswithdispersedstructurespreferentiallyoccursatthedropletsurface.Asinglenucleationeventtakesplacemorefrequentlyasdropletsizeisreduced.
简介:Thedevelopmentofthermalanalysistechniquesforevaluationofcastalloymeltqualityanditscurrentapplicationsinthefoundrywerereviewed.Thecharacteristicsofthecurrentthermalanalysistechniqueswereanalyzed.Anewcomprehensivemethodforcoolingcurverecognitionhasbeenproposed.Theevaluationofcastalloymeltqualitywasrealized.
简介:TheX-raydiffractionpeak-shiftmethodwasintroducedintothedeterminationofdeformationfaultprobability(α)ofFe-Mn-SialloyswithvariousMncontentsandthermomechanicalcyclingnumbers.Thepreciselatticeconstantsrequiredwereobtainedbynumericalcalculationinsteadofusingstandardsamplewithoutanyfault.Theinfluenceofinternalstressonthedeterminedαhasbeenevaluated,andthecausedrelativeerrorwasdeterminedasabout4%andthusnegligible.TheresultsshowthatthedeformationfaultprobabilityincreaseswithdecreasingMn-contentandincreasingcyclenumber,whicharequalitativelyconsistentwiththoseresultsofPsfdeterminedbypeak-broadeningmethod.
简介:InthisstudyweconductedsingleV-groovebuttwelding(GTAW)onthreetypesofheattreatablealuminumalloys2024-T351,6061-T6and7075-T6andcomparedtheangulardistortionlevelsofthethreealuminumalloysatdifferentVeepreparationangleswithorwithoutrestraint.ExperimentalresultsdemonstratedthatwhentheVeepreparationanglewas0°(I-shapedgroove),theangulardistortionleveloftherestrainedweldmentcanexceedthatoftheunrestrainedweldments.Moreover,whentheVeepreparationanglewas45°,60°or90°,therestrainedweldmenthadlowerangulardistortionthantheunrestrainedweldments.ThesingleVeepreparationangle(amountoffillermetal)inbuttweldingaffectedtheangulardistortionoftheweldment.Withoutrestraint,theangulardistortiontendedtoincreasewiththesingleVeepreparationangle.Meanwhile,theangulardistortiontendedtodecreasewhenthesingleVeepreparationanglewas60°.Additionally,arestrainedweldmenthadhighangulardistortionwhenthesingleVeepreparationanglewas0°.Notably,theangulardistortiontendedtoreducewithincreasingsingleVeepreparationangle.Theangulardistortionoftheweldmentwasminimizedatanangleof60°.However,theangulardistortionincreasedwhentheVeepreparationangleexceeded60°.Thehigh-temperatureyieldstrengthofamaterialalsoaffecteditsangulardistortion.Angulardistortionincreasedwithhigh-temperatureyieldstrength.Experimentalresultsalsoshowedthat,fromthestrongesttotheweakest,thehigh-temperatureyieldstrengthofthethreetypesofaluminumalloysfollowedtheorder6061-T6and2024-T351>7075-T6.
简介:DropletsofCo-37.6wtpctMoandNi-47.7wtpctMoeutecticalloyswererapidlysolidifiedduringcontainerlessprocessingina3mdroptube.Akindofanomalouseutecticappearsinthesetwoeutecticalloyswhenundercoolingisbeyond56and61K,respectively.Thetwoeutecticphasesinanomalouseutecticwereobservedtogrowindendritemanner.Theformationofanomalouseutecticisascribedtothecooperativedendritegrowthofthetwoindependentlynucleatedeutecticphases.Currentdendriteandeutecticgrowththeoriesareappliedtodescribetheobservedprocesses.
简介:Basedontheclassicdiffusioncontrollednucleationandgrowththeory,thesympatheticnucleationledgewisegrowthmechanismofbainitewasstudiedtheoreticallyforIowcarbonFe-Calloys.Therationalityoftheoccurrenceofsympatheticnucleationontheterracesofledgescompetingwithlateralledgegrowthandothersitesnucleationwasdemonstratedbythepresentworkquantitatively.ThecalculationsindicatedthatIowreactiontemperaturesandhighcarbonconcentrationsmayfavorthesympatheticnucleation,thusaccountingfortheformationofmultilayerstructuresofbainite.
简介:InvestigationhasbeencarriedouttofindtheeffectsofNdsubstitutionandCuadditiononthehydrogenstoragepropertiesofAB5-typealloywithamulticomponentLa0.6M0.4Ni4.8Mn0.2(M=Y,Nd)system.La0.6Y0.4Ni4.8Mn0.2,whichwasusedinanair-conditioningsystem,showedpoorhysteresisandslopingcharacteristics,whichledtoadecreaseconcerningthecoefficientofperformanceofthesystem.BythesubstitutionofNdforY,thehydrogenstoragecapacityincreased,andtheplateaupressuredecreasedalittle,butthehydrogenabsorptionkineticsdecreaseddramatically.CuadditioncaneffectivelyimprovethekineticsofhydrideformationwithoutchangingthehydrogenstoragecapacityofLa0.6Nd0.4Ni4.8Mn0.2.IthasbeenfoundthatLa0.6Nd0.4Ni4.8Mn0.2Cu0.1alloyshowedgoodhydrogenstoragecharacteristicsformetalhydrideair-conditioningsystem.Theresultsshowedthat,foreachcomponentofLa0.6Mo.4Ni4.8Mn0.2,theeffectivehydrogenstoragecapacityincreasedwithdecreaseoftheunitcellparameterc/aandthehydrogenabsorptionplateaupressureincreasedwithdecreaseoftheparametera.
简介:Thestudyofthetriplejunctionsofthegrainboundariesinsomefccsolidsolutions,orderedalloysandintermetallicswithL12hasbeencarriedoutusingtheopticalmetallographyandTEMmethods.Two-typesofthetriplejunctionswerefoundinthealloysinvestigated(1),consistingoftheboundariesoftherandom(RT),and(2),consistingoftheRTboundaryandthespecialboundaries(ST).TherelativevaluesoftheRTandSTboundaryenergyweredeterminedonthebasisofthemeasurementsoftheanglesbetweenthegrainboundaryplanes.IthasbeenshownthattheenergyofSTboundariesincreaseswiththeincreaseofthestackingfault(SF)energy.TheenergyoftheRTboundariesdoesnotdependontheSFenergy.
简介:有双阶段的结构(alpha+beta)的alpha钛和它的合金在大约10~的紧张率下面动态地被使变形4s~(-1)。形成和微结构进化局部性砍乐队们被扫描电子显微镜学(SEM)和传播电子显微镜学(TEM)描绘。结果表明紧张和紧张率应该同时被看作机械条件为砍乐队形成,和twinning是变丑的一个重要模式。试验性并且在乐队以内的材料经历了的计算表演超高频率的紧张率(9X10~5s~(-1))变丑,它是平均紧张率的二大小要求了为砍乐队形成;在乐队的脱臼能被压缩并且发展成房间结构;到在乐队以内的alpha_2的阶段转变fromalpha被观察,并且转变产品(alpha_2)与他们的父母一起有某个结晶的取向关系;有在在乐队以内观察的直径的10亩m的一种平均尺寸的equiaxed谷物被建议是再结晶的结果。
简介:ThedensityofNi-Alalloysinbothliquidstateandsolid-liquidcoexistencestatewasmeasuredwithamodifiedpycnometricmethod.ItwasfoundthatthedensityofNI-AlalloysdecreaseswithincreasingtemperatureandAlconcentrationinthealloys.ThemolarvolumeofliquidNi-AlbinaryalloysincreaseswiththeincreaseoftemperatureandAlconcentration.ThepartialmolarvolumeofAlinNI-Albinaryalloywascalculatedapproximately.ThemolarvolumeofliquidNI-Alalloydeterminedinthepresentworkshowsanegativedeviationfromtheideallinearmolarvolume.
简介:1.IntroductionSofarthemicrostructureandcoercivityofSm(Co,Cu,Fe,Zr)7.4alloyhavebeenstudiedindetailbyvariousauthors.TheeffectofZr-richlaminarphasestructureonthehighcoecivityofalloyismoreattractive.Thechangesofmagnetic