Microstructure and mechanical properties of TiAl/Ni-based superalloy joints vacuum brazed with Ti–Zr–Fe–Cu–Ni–Co–Mo filler metal

• Published in: Rare metals Vol. 40; no. 8; pp. 2134 - 2142
• Main Authors: Wan, Bao, Li, Xiao-Qiang, Pan, Cun-Liang, Li, Dong-Yu, Qu, Sheng-Guan, Yang, Chao
• Format: Journal Article
• Language: English
• Published: Beijing Nonferrous Metals Society of China 01.08.2021; Springer Nature B.V
• Subjects: Aerospace vehicles; Biomaterials; Brazed joints; Chemical composition; Chemistry and Materials Science; Chromium; Cobalt; Copper; Energy; Filler metals; High temperature; Intermetallic compounds; Iron; Materials Engineering; Materials Science; Mechanical properties; Metallic Materials; Microcracks; Microstructure; Molybdenum; Nanoscale Science and Technology; Nickel base alloys; Original Article; Physical Chemistry; Room temperature; Seams; Shear strength; Solid solutions; Substrates; Superalloys; Thickness; Titanium aluminides; Vacuum brazing; Weight reduction; Shear strength; Brazing; Ni-based superalloy; Microstructure; TiAl alloy
• ISSN: 1001-0521; 1867-7185
• DOI: 10.1007/s12598-020-01550-x

For the purpose of elevated temperature service and weight reduction in aerospace vehicle applications, a novel Ti–Zr–Fe–Cu–Ni–Co–Mo filler metal was employed to join TiAl to Ni-based superalloy (GH536). The effects of brazing temperature on interfacial microstructure and chemical composition of the joints were analyzed. The representative joint microstructure from TiAl substrate to GH536 substrate was primarily composed of four characteristic layers in order: B 2 ; Al 3 NiTi 2 ; AlNi 2 Ti containing Cr-rich (Cr, Ni, Fe) ss (subscript ss represents solid solution), Ni-rich (Ni, Cr, Fe) ss and TiNi 3 ; Cr-rich (Cr, Ni, Fe) ss containing AlNi 2 Ti, Ni-rich (Ni, Cr, Fe) ss and TiNi 3 . Layer IV has the majority of the brazing seam, while Layer II was the thinnest. And the thickness of Layer II was not affected by brazing temperature. With the increase in brazing temperature in the range of 1110–1170 °C, both the shear strength and the thickness of brazing seam firstly increased and then decreased. The joint performance was jointly controlled by the thickness of brazing seam, the amounts of microcracks and intermetallic compounds formed in brazing seam. The maximum shear strength of 183 MPa at room temperature was obtained together with a peak thickness when the joint was brazed at 1150 °C for 10 min and the shear fracture mainly occurred in the thinnest Layer II Al 3 NiTi 2 . Graphic abstract