A Novel TiAl/GH4099 joining strategy utilizing the superplasticity of undercooled bulk metallic glass

Bulk metallic glasses (BMGs) exhibit unique properties, including ultra-high strength, exceptional hardness, and superplasticity in the supercooled liquid region, due to their defect-free atomic structure. In this study, the superplasticity of BMGs was exploited to achieve high-strength bonding between high-temperature alloys. A 0.5 mm-thick Ni₆₂Nb₃₈ amorphous interlayer was fabricated using vacuum die-casting technology and employed for joining TiAl and GH4099 alloys. The results demonstrated that the interlayer produced via vacuum pressing exhibited superior stability and performance consistency compared to the amorphous ribbon solder prepared by conventional single-roll melt spinning. The shrinkage behavior of interfacial pores in the supercooled liquid region, along with the subsequent atomic diffusion and microstructural evolution at elevated temperatures, was analyzed via X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM), and selected area electron diffraction (SAED) techniques. The findings revealed the formation of a robust metallurgical bond, where the joint consists of the γ-TiAl/Ti₃Al/AlNi₂Ti/NiNb and Ni₃Nb/γ-Ni phases. Shear tests performed at room temperature and 750 °C were employed to assess the bonding strength, revealing that the joint achieved shear strengths of up to 315 MPa at room temperature and 250 MPa at 750 °C.