Microstructural characterization of electron beam welded joints of TiAl-based intermetallic compound  

作　　者：WUHuiqiang FENGJicai HEJingshan ZHOULi 

机构地区：[1]NationalKeyLaboratoryofAdvancedWeldingProductionTechnology,HarbinInstituteofTechnology,Harbin150001,China

出　　处：《Rare Metals》2005年第1期82-86,共5页稀有金属（英文版）

基　　金：ThisprojectisfinanciallysupportedbytheNationalHigh-TechResearchandDevelopmentProgramofChina(863Program,No.2002AA724040).

摘　　要：The feasibility to use electron beam welding to join the nominal compositionTi-48Al-2Cr-2Nb (at. percent) alloy was assessed. The microstructure characterization and crackingsusceptibility of the joints were evaluated by means of OM, SEM, XRD, and microhardness. It wasfound that the welded microstructure exhibited columnar and dendritic structures. Microstructuralconstituents in the fusion zone were a massive gamma structure and some amount of lamellar structureconsisting of alternating platelets of alpha_2 and gamma. The major contributing factor to thesusceptibility to solidification cracking was microsturctural change in this study for thesuppression of a phase decomposition leading to produce more retained alpha_2 brittle phase.Compared with transgranular cleavage fracture in the base metal, the weld metal exhibited mainlytranslamellar fracture.The feasibility to use electron beam welding to join the nominal compositionTi-48Al-2Cr-2Nb (at. percent) alloy was assessed. The microstructure characterization and crackingsusceptibility of the joints were evaluated by means of OM, SEM, XRD, and microhardness. It wasfound that the welded microstructure exhibited columnar and dendritic structures. Microstructuralconstituents in the fusion zone were a massive gamma structure and some amount of lamellar structureconsisting of alternating platelets of alpha_2 and gamma. The major contributing factor to thesusceptibility to solidification cracking was microsturctural change in this study for thesuppression of a phase decomposition leading to produce more retained alpha_2 brittle phase.Compared with transgranular cleavage fracture in the base metal, the weld metal exhibited mainlytranslamellar fracture.

关 键 词：electron beam welding titanium aluminide MICROSTRUCTURE CRACK 

分 类 号：TG146.21[一般工业技术—材料科学与工程] TG444[金属学及工艺—金属材料]