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.