简介:Howtocontrolmeltcompositionisthekeyforgettinghighqualityalloymelt.Thepapermadethefollowingefforts:(1)TheactivitycoefficientsinTi-15-3melthavebeencalculated.(2)Takingadvantageoftheactivitycoefficients,theevaporationlossesofcomponentsinTi-15-3meltduringISMprocesshavebeenstudied.Thecalculatedresultsshowthatthereisacriticalvacuumdegree(about1.33Pa)duringmeltingprocess.
简介:AmodelhasbeendevelopedtodescribethemicrostructureevolutionintheatomizeddropletsofCu-Fealloyduringcoolingthroughthemetastablemiscibilitygap.CalculationshavebeenperformedforCu85Fe15alloytoinvestigatetheprocessofliquid-liquidphasetransformation.Thenumericalresultsindicatethattheminorityphasedropletsarenucleatedinatemperatureregionaroundthepeakofthesupersaturation.TheaverageradiusoftheFe-richdropletsdecreasesandthenumberdensityoftheminorityphasedropletsincreaseswithdecreasingtheatomizeddropletsize.Thesimulatedresultswerecomparedwiththeexperimentalones.Thekineticprocessoftheliquid-liquidphasetransformationwasdiscussedindetail.
简介:Microstructureandsubsequentphasetransformationsonheatingofthemelt-spunNd85Al15alloyhavebeenstudiedbyX-raydiffraction,transmissionelectronmicroscopyanddifferentialscanningcalorimetry.Themelt-spunNd85Al15alloyshowstwo-stagetransformationprocessesasfollows:amorphous+72nmsupersaturatedbcc-Nd(Al)solidsolution→7nmomega-likephase→AlNd3+hexagonalNd.Theactivationenergiesforthefirstandsecondtransformationwerefoundtobe100kJ/moland188kJ/mol,respectively.Theformationmechanismofnanoscaleomega-likephaseisdiscussed.
简介:Anas-castmagnesiumalloywithhighAlcontentMg15Alwassubjectedtoequal-channelangularpressing(ECAP)throughadiewithanangleofφ=90?at553KfollowingrouteBc.Itisfoundthatthenetworkβ-Mg17Al12phasesintheas-castMg15Alalloyarebrokenintosmallblocksanddisperseduniformlywithincreasingnumbersofpressingpasses.Moreover,manynano-sizedMg17Al12particlesprecipitateintheultra-fineα-Mgmatrix.Thegrainsareobviouslyrefined.However,thegrainstructureisinhomogeneousindifferentareasofthealloy.Theaveragesizeoftheprimaryphaseα-Mgisreducedtoabout1μmwhilegrainsofaround0.1-0.2μmareobtainedinsometwo-phaseareas.WithadditionalECAPpasses(upto8),coarseningofthegrainsoccursbydynamicrecovery.RoomtemperaturetensiletestsshowthatthemechanicalpropertiesofMg15Alalloysaremarkedlyimprovedafter4ECAPpasses.Theultimatetensilestrengthandelongationtofailureincreasefrom150MPato269.3MPaandfrom0.05%to7.4%,respectively.Comparedwiththatafter4passes,theelongationtofailureofthealloyincreasesbutthestrengthofthealloyslightlydecreasesafter8ECAPpasses.FracturemorphologyoftheECAP-processedalloyexhibitsdimple-likefracturecharacteristicswhiletheas-castalloyshowsquasi-cleavagefractures.
简介:喷洒的Zn和Zn15Al涂层被选择保护对的高张力水泥(PHC)的结束输送的金属的弧在东北中国在北瓷器和中立草地土壤对盐咸滩土壤的腐蚀堆。在二个模仿的土壤答案的涂的Q235钢样品的腐蚀行为被potentiodynamic极化和电气化学的阻抗光谱学(EIS)调查方法。试验性的结果证明在两个都模仿的答案的矩阵Q235钢的腐蚀被Zn和Zn15Al涂层显著地禁止。Zn和Zn15Al上的腐蚀产品厚、紧缩、坚挺、保护。Zn和Zn15Al涂的样品的腐蚀水流密度icorr与腐蚀时间,和费用转移电阻Rct显然被减少极大地被增加。在模仿的中立草地土壤答案的Zn和Zn15Al的腐蚀电阻索引是比在盐咸滩土壤的那些更突出的。在盐咸滩土壤的Zn15Al的腐蚀电阻比Zn的稍微优异。当喷洒的涂层与环氧基树脂树脂被封上时,涂层的腐蚀电阻进一步显著地被提高。
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简介:Er^3+-dopedSrBi4Ti4O15-Bi4Ti3O12(SBT-BIT-xEr^3+,x=0.00,0.05,0.10,0.15and0.20)inter-growthceramicsweresynthesizedbythesolid-statereactionmethod.Structural,electricalandup-conversionpropertiesofSBT-BIT-xEr^3+wereinvestigated.Allsamplesshowedasinglephaseoftheorthorhombicstructure.RamanspectroscopyindicatedthattheEr^3+substitutionforBi^3+atAsitesofthepseudo-perovskitelayerincreasesthelatticedistortionofSBT-BIT-xEr^3+ceramics.ThesubstitutionofBi^3+byEr^3+leadstoadecreaseofdielectriclosstanδandanincreaseofconductivityactivationenergy.Piezoelectricconstantd33wasslightlyimproved,butdielectricconstantwasdecreasedwiththeEr^3+doping.TheSBT-BIT-xEr^3+ceramicwithx=0.15exhibitstheoptimizedelectricalbehavior(d33~17pC/N,tanδ~0.83%).Moreover,twobrightgreen(532and548nm)andonered(670nm)emissionbandswereobservedunderthe980nmexcitation.Optimizedemissionintensitywasalsoobtainedwhenx=0.15fortheSBT-BIT-xEr^3+ceramic.Therefore,thiskindofceramicsoughttobepromisingcandidatesformultifunctionaloptoelectronicapplications.