Diffusion bonding of TC4/TB8 titanium alloys with an interlayer by regulating temperature: Microstructure and mechanical performance

• Published in: Thin-walled structures 2025-03, Vol.208, p.112760, Article 112760
• Main Authors: Li, Tianle, Wu, Renhao, SaGong, Man Jae, Toor, Zaigham Saeed, Kim, Hyoung Seop
• Format: Article
• Language: English
• Subjects: Bonded interface; Deformation mechanism; Interlayer; Temperature; Titanium alloys
• ISSN: 0263-8231
• DOI: 10.1016/j.tws.2024.112760

•Phase transformations dominate atomic diffusion across the joints.•The α/β transformation relies on compositional fluctuations and temperature.•Dislocation accumulation at boundaries results from multiple slip & tangling.•A two-step method can optimize the microstructure and mechanical performance. Diffusion bonding of α+β type TC4 (Ti-6Al-4V) and metastable β type TB8 (Ti-15Mo-2.7Nb-3Al-0.2Si) alloys with interlayer addition was systematically investigated by regulating temperature, revealing the discrepancies in interfacial microstructure and mechanical performance of the joints. Microstructural evolution at the TC4/Ti interfaces and TB8/Ti interfaces can be attributed to atomic interdiffusion and α/β transformation depending on temperature. Additionally, 7 of the 12 α variants that comply with the Burgers orientation relationship with β parents at the transitional layer are identified. The elongation of the bonded samples upon the tensile direction perpendicular to the interfaces becomes decreased compared to that of samples subjected to the tensile direction parallel to the interfaces. The dislocation characteristics and fracture models are analyzed after plastic deformation. This study indicates that a two-step method (first high-temperature and short-duration, then low-temperature and long-duration) can optimize the microstructure and mechanical performance of joints for Ti alloys exposed to high temperatures. [Display omitted]