nitinb2ftc4激光的微焊接裂纹形成机理与控制方法的研究

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1、butwhenNiTiNbplacesintheupper,put50μmthickessofthinplateofNiinthemiddle,nocrackisfoundintheweld.However,brittleTi2Niphaseisfonudatthebottomwithparentmetal.ForNiTiNb/TC4dissimilarmaterialsbuttjoints,whenfillinginapureNiwirewithdiameterofΦ300μm,thereisacracknearthe

2、fusionlineatthesideofTC4.ATi2Niphaseareaabout20μmwideisfoundatthesideoftheTC4,whilethecombinationisverygoodatthesideofNiTiNb.Themaximumtensilestrengthofthejointis322MPa.FillinapureTiwirewiththediameterofΦ300μm,microcracksarefoundinthesurfaceoftheweld.ATi2Niphasez

3、oneabout10μmwideisobservedatthesideofNiTiNb.Themaximumtensilestrengthofthejointis447MPa.FillinapureNbwirewiththediameterofΦ300μm,theformingoftheweldsurfaceisverygood,andnocrackdefectinthejoint.Themaximumtensilestrengthofthejointis740MPa,whichisupto82%ofthebasemat

4、erialofannealedstateofTC4.Keywords：lasermicro-welding;NiTiNb/TC4titaniumalloydissimilarmaterials;weldingcracks;microstructure;propertiesIII南昌航空大学硕士学位论文目录目录摘要..........................................................................................................

5、....................................IAbstract............................................................................................................................................II目录..........................................................................

6、..................................................................IV第1章绪论.....................................................................................................................................11.1选题的依据、目的及意义..........................................

7、.......................................................11.2NiTiNb与TC4的性能特点及应用现状..........................................................................21.3NiTiNb与TC4的焊接技术现状......................................................................................41.

8、3.1NiTiNb与TC4的焊接冶金特点...........................................................................41.3.2NiTiNb同种材料焊接现状............................................