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1、Al-Cu-Li合金电子束焊接工艺及接头组织与性能溶液中浸泡96h后，未观察到有明显的剥蚀现象。电化学腐蚀试验测试结果表明，焊接接头的耐蚀性能好于Al-Cu-Li合金母材。关键词：Al-Cu-Li合金，电子束焊，显微组织，力学性能，焊后热处理，耐蚀性II南京航空航天大学硕士学位论文ABSTRACTNowadays,withtherapiddevelopmentofaerospaceindustry,aluminum-lithiumalloysasastructurematerialwithexcell
2、entproperties,haveincreasinglyreceivedconsiderableattentionasreplacementofconventionalaluminumalloys.Atpresent,Al-Lialloysappliedinengineeringarethethird-generationalloys.Comparedwiththesecond-generationAl-Lialloys,thenewgenerationAl-Lialloyshaveexcelle
3、ntcomprehensiveproperties,suchasthewellbalancebetweenstrengthandtoughness,gooddamagetolerance,lowanisotropyofmechanicalproperties,thermalstability,corrosionresistanceandwellformability,etc.However,duetothehighchemicalactivityofLielement,welddefectssucha
4、sweldporosityandhotcrackwillappearwhentheconventionalweldingmethodsareusedtoweldthesenovelAl-Cu-Lialloys.Sotheweldedjointswithbetterqualityaredifficulttobeobtained.Comparedwiththecommonweldingmethods,electronbeamweldinghasmanyadvantagesincludinghighener
5、gydensity,anarrowheat-affectedzone,lowdistortionandgoodatmosphereasweldingisperformedinahighvacuum.Therefore,itissuperiortoweldAl-Cu-Lialloys.Basedonthese,inthispaper,theelectronbeamwelding(EBW)ofAl-Cu-Lialloyswith2.5mmthicknessisinvestigated.Theeffecto
6、felectronbeamcurrentontheweldappearence,microstructureandmechanicalpropertiesofweldedjointsarestudied.Moreover,inordertoimprovethemicrostructureandmechanicalpropertiesofweldedjoints,thepost-weldheattreatment(PWHT)includingsolutionandagingiscarriedouttot
7、hejoints.Besides,thecorrosionresistanceofweldedjointsisalsosystematicallyevaluated.Themicrostructureobservationofweldedjointsshowsthatas-weldedAl-Cu-LialloysEBWjointsexhibitthreeregions,namely,fineequiaxedgrainszone(EQZ),columnarcrystalsandequiaxedcryst
8、alsrespectivelyfromfusionzonetothecenterofweldment.TheequiaxedgrainszoneformednearfusionlineisrelatedtoZrandLielementinAl-Lialloys.Atthesametime,theunitedrecrystallizationintheedgeofmoltenpoolisrestrainedbyEQZ.Therearealotofeutec
