A concept of regulating the distribution of continuous brittle phases by spatial division of the Ti3SiC2/Ti2AlNb brazing seam

Abstract

Herein, a novel concept was proposed to address the issue that continuous brittle phases degrade the mechanical properties of a brazed joint. In this concept, the continuous brittle phases could become dispersive by inserting a network-like structure to divide the brazing seam spatially. This concept was verified in a specific brazing system, where Ti3SiC2 ceramic and Ti2AlNb alloy were brazed by an AgCu interlayer. Ductile Cu foam with a network-like structure was used to disperse the continuous brittle TiCuSi intermetallic that should have in-situ formed in the Ti3SiC2/AgCu/Ti2AlNb brazed joint. Results show that the effect of Cu foam on dispersing the brittle TiCuSi intermetallic is pronounced. The effects of holding time and pore size on the dispersion effect of Cu foam were investigated. The joint fracture analysis and micro-mechanical properties of phases analysis reveal that the dispersive TiCuSi intermetallic is superior to the continuous one. The reason is that the microstructure of discrete TiCuSi intermetallic surrounded by ductile Ag-based and Cu-based solid solutions has a more robust capacity to accommodate microcracks. Thus the brazed joint is toughened and strengthened.