Microstructures, mechanical properties and formation mechanisms of tungsten heavy alloy brazed joints using Cu-Ti-Ni-Zr amorphous filler

• Published in: Materials & design 2022-11, Vol.223, p.111181, Article 111181
• Main Authors: Xu, Yuxin, Qiu, Xiaoming, Wang, Suyu, Wu, Chao, Su, Jinlong, Xing, Fei
• Format: Article
• Language: English
• Subjects: Amorphous brazing filler; Mechanical property; Microstructure; Tungsten heavy alloy (WHA)
• ISSN: 0264-1275; 1873-4197
• DOI: 10.1016/j.matdes.2022.111181

[Display omitted] •Brazing of tungsten heavy alloy was conducted with Cu-Ti-Ni-Zr amorphous filler, which could reduce the joining temperature with elevated room-temperature and high-temperature joint strength.•The effects of brazing temperature and holding time were analyzed, and the correlation between microstructures and joint properties was established.•The underlying joining mechanism considering the distribution of hard tungsten phase and the interaction between binder phase and liquid filler were proposed. Vacuum brazing of tungsten heavy alloys (WHAs) was conducted with a design of Cu-Ti-Ni-Zr amorphous filler. The effects of key brazing parameters (brazing temperature T, holding time t) on interfacial microstructures and mechanical properties were investigated. The typical microstructure of brazing seam was composed of CuTi eutectic, CuZr dendrites along with (Cu, Ti) (Ni, Zr) and (Cu, Ni) Ti2 phases. With the brazing temperature increased from 850 °C to 1000 °C, the phenomenon of “infiltration induced separation of adjacent W grains” was intensively expanded, which was addressed in view of the Marangoni convection effect, atom diffusion, internal reaction, and grain boundary wetting. The maximum shear strength of the joint brazed at 925 °C for 20 min reached 366.6 MPa. This first detailed study on wettability, interfacial microstructures, and joining mechanism of WHAs brazed joints can benefit an in-depth understanding in joining process of WHAs, which can also provide guidance for joining of sintered dual/multi-phase refractory composites.