Progress, applications, and perspectives of titanium-based braze filler metal: a review

The progress of materials has never stopped, and the joining process of dissimilar materials is still a serious challenge. Vacuum brazing technology is a joining process developed in the 1940s and still meets the challenges of advanced dissimilar material joining. The choice of filler metal directly determines the performance of the brazing joint. Titanium-based filler metal is widely used because of its excellent properties. Titanium-based fillers of different compositions and contents are used to address various joining challenges and facilitate material advancements. In recent decades, dozens of types of titanium-based fillers have been developed, mainly focusing on the continuous optimization of the element types and composition content in the fillers. This paper reviews the development of titanium-based filler metal in recent years. The unique roles of common Ti, Zr, Co, Be, Mo, V, Nb, RE, and other elements in the components of titanium-based filler metal are summarized. The melting point of the filler metal with different element combinations and different content combinations and the mechanical strength of the experimental joints were compared. In addition, the characteristics, classification, and production methods of titanium-based filler metal are introduced, and the main application fields and brazing materials of titanium-based filler metal are discussed. Finally, the future development and challenges of titanium-based filler metal are proposed, and the prospect is made in order to provide reference for the future research on dissimilar material connection.