Development of the interlayer alloy using for TLP diffusion bonding of GH3230 superalloy based on the CALPHAD method

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Vol. 918; p. 147434
• Main Authors: Zhang, Sihan, Qu, Wenqing, Teng, Junfei, Lyu, Yanlong, Zhao, Haiyun, Zhuang, Hongshou
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.12.2024
• Subjects: GH3230 superalloy; High-performance joining; Interlayer design; Tensile strength; TLP diffusion bonding; TLP diffusion bonding; GH3230 superalloy; Interlayer design; Tensile strength; High-performance joining
• ISSN: 0921-5093
• DOI: 10.1016/j.msea.2024.147434

The hot-end components of aero-engines and gas turbines not only require high-temperature alloys capable of withstanding extreme temperatures, but also demand welds with high-temperature-resistant properties. In this study, the CALPHAD method was employed, utilizing the thermodynamic theory of phase diagrams with Thermo-Calc software and the corresponding database, to design the interlayer composition for superalloy TLP diffusion connections. The optimization aimed to determine the interlayer material's solidus-liquidus and compound phase content, resulting in the selection of a new nickel-based interlayer material containing B as MPD, with Co and W as strengthening elements. Using GH3230 alloy as the research subject, TLP diffusion bonding experiments were conducted at a welding temperature of 1200 °C with a holding time of 4 h. The weld zone exhibited no defects, and the microstructure was identical to that of the GH3230 base metal, consisting entirely of a solid solution. High-temperature tensile tests revealed that fractures consistently occurred in the GH3230 base metal, indicating that the weld's strength significantly exceeded that of the base metal. The average tensile strength of GH3230 high-temperature alloy bar tensile simulated specimens is 899 MPa at room temperature and 213 MPa at high temperature. In addition, the 90° three-point bend test showed no cracking in the weld area, indicating adequate plasticity. •The development of interlayer using Thermal-Calc and TCHEA6 database can obtain high accuracy, and save costs.•The developed amorphous KNi-5(Ni-Cr-Co-W-B) interlayer is suitable for TLP diffusion bonding of GH3230 superalloy.•A solid solution structure formed in the interface with excellent mechanical properties and temperature resistance.