1 Aeronautical Key Laboratory for Welding and Joining Technologies, AVIC Manufacturing Technology Institute, Beijing 100024, China 2 School of Materials Science and Engineering, Dalian Jiaotong University, Dalian 116028, Liaoning, China
TiAl/Ti2AlNb dissimilar alloys were successfully bonded together by spark plasma diffusion bonding. The joints were subjected to post-weld heat treatment at different temperatures. The microstructure of the welded joint was analyzed and the tensile strength and microhardness of the joint were tested. The results indicate that after heat treatment, the microstructure of Ti2AlNb base metal, TiAl base metal and interface has no obvious change. In the Ti2AlNb heat affected zone(HAZ), most B2 phase gradually turns into O phase, due to the precipitation of acicular O phase, the microhardness increases significantly compared to as welded condition. With the increase of heat treatment temperature, the microhardness of the Ti2AlNb HAZ gradually decreases, meanwhile, the tensile strength of the joint at room temperature shows an evident increase compared to as welded. The maximum tensile strength of the joint reaches 376 MPa at heat treatment temperature of 900℃. After heat treatment, the fracture mode of the joint is brittle fracture.
LORIA E A . Gamma titanium aluminides as prospective structural materials[J]. Intermetallics, 2000, 8 (9/11): 1339- 1345.
WEI H E , TANG H P , LIU H Y , et al. Microstructure and tensile properties of containerless near-isothermally forged TiAl alloys[J]. Transactions of Nonferrous Metals Society of China, 2011, 21 (12): 2605- 2609.
KONG F , CHEN Y , ZHANG D , et al. High temperature deformation behavior of Ti-46Al-2Cr-4Nb-0.2Y alloy[J]. Materials Science and Engineering: A, 2012, 539 (2): 107- 114.
LIU J Q. Research on brazing process and mechanism of TiAl/Ti2AlNb alloy joint[D]. Harbin: Harbin Institute of Technology, 2016.
CAO J , DAI X Y , LIU J Q , et al. Relationship between microstructure and mechanical properties of TiAl/Ti2AlNb joint brazed using Ti-27Co eutectic filler metal[J]. Materials & Design, 2017, 121, 176- 184.
REN H S , XIONG H P , CHEN B , et al. Transient liquid phase diffusion bonding of Ti3Al/TiAl joint using a Ti-Zr-Cu-Ni-Fe interlayer[J]. Transactions of the China Welding Institution, 2016, 37 (3): 106- 110.
REN H S , XIONG H P , PANG S J , et al. Microstructures and mechanical properties of transient liquid-phase diffusion-bonded Ti3Al/TiAl joints with Ti-Zr-Cu-Ni interlayer[J]. Metallurgical and Materials Transactions A, 2016, 47 (4): 1668- 1676.
WU B , SHEN J Y , SHANG S L , et al. Prediction of phase equilibrium in Ti-22Al-27Nb alloy[J]. Chinese Journal of Rare Metals, 2002, 26 (1): 12- 14.
张永刚. 金属间化合物结构材料[M]. 北京: 国防工业出版社, 2001: 795- 797.
ZHANG Y G . Intermetallic compound structural material[M]. Beijing: National Defense Industry Press, 2001: 795- 797.
CHEN X , XIE F Q , MA T J , et al. Microstructure evolution and mechanical properties of linear friction welded Ti2AlNb alloy[J]. Journal of Alloys and Compounds, 2015, 646, 490- 496.
WANG W , ZENG W D , XUE C , et al. Quantitative analysis of the effect of heat treatment on microstructural evolution and microhardness of an isothermally forged Ti-22Al-25Nb (at.%) orthorhombic alloy[J]. Intermetallics, 2014, 45, 29- 37.