ti2alnb基合金的热变形行为及加工图研究

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1、AbstractTi2AlNb-basedalloyisadvancedstructuralmaterialappliedinairlineandindustryandhascomprehensivelyexcellentmechanicalpropertiesinhighspecificstrength,specificstiffness,fracturetoughnessandcreepresistance.Therefore,Ti2AlNb-basedalloyisanewstudyhot-spotininte

2、rmetalliccompoundresearchfieldwithagreatrangeofpotentialutilitiesandaprospectofdevelopment.However,Ti2AlNb-basedalloyisdifficult-to-deformationmaterial.Itsorganizationandpropertyareextremelysensitivetothedeformationparameters,soit’shardtogetproductsstableinorga

3、nizationandproperty,andthehighcostofmanufacturerestrictsitsapplicationrange.ThispaperconsidersTi2AlNb-basedalloy.Theisothermalconstantstrainratecompressionexperimentswereconductedbetween900~1110℃and0.01~10s-1deformationparameter.Theauthoranalyzedthetruestress-s

4、traincurves,calculatedthisalloy’sactivationenergyandconstructedaconstitutiveequationwithhighaccuracy.ProcessingmapsindifferentdependentvariablesweredrewaccordingtoPrasadandMurtycriterions.Theauthoralsostudiedtheanalysisdiagramwiththemicrostructureandgottheinsta

5、bilityregions,thebetterhotworkingareaanditscorrespondingthermodynamicparametersanddeformationmechanism.Mainresultsareasfollows.FlowstresscurveofTi2AlNb-basedalloyhasfeatureslikestresspeak,flowsofteningandsteadystateflow.Flowstressdecreaseswiththeincreaseofdefor

6、mationtemperatureandthedecreaseofstrainrate.Accordingtothecalculation,Ti2AlNb-basedalloy’sactivationenergyQ=358.24KJ/mol,whichisobviouslybiggerthanselfdiffusionactivationenergyofpureαtitaniumandpureβtitaniumalloy.ThisshowsthatthermaldeformationofTi2AlNb-basedal

7、loyiscontrolledbyprocesseseliminatehightemperaturediffusion.Aconstitutiveequationwithhighaccuracyisconstructed,andtheerroranalysisshowsthatinallthedatapoints,datapointsoflessthan15%errorsaccountedfor93.8%and90.8%.Processingmapsindifferentdependentvariableswered

8、rewaccordingtoPrasadandMurtycriterionsseparately.Bythecomparisonofthesetwokindsofprocessingmaps,theauthorfoundthatthistwohasasimilarpredictionofinstabilityregion,butwhencons