Brazing of Titanium with Silver-Base Filler Metals

Abstract

The properties of brazed joint of titanium with silver-base filler metals have been examined, and an improvement of the filler metals has been made to find ones suitable for vacuum and inert-gas atmosphere brazing. It is found that the increase in the Cu-content of Ag-Cu filler metal increases the brittleness of the joint, the upper limit allowable being about 10% Cu. With electron-probe microanalysis, Cu in the brazement is found to be concentrated around the base metal/filler metal interface. By addition of Ni to the filler alloy, the microstructure of brazement is changed and the distribution of Cu becomes more uniform, resulting in an improvement of mechanical properties of the joint. The alloys Ag-15 Cu-3Ni and Ag-20Cu-3Ni are proved to give joints with satisfactory strength by vacuum brazing. The joints brazed in argon atmosphere by Li-containing Ag-Cu-Ni alloy show similar strength to that brazed in vacuum by Li-free Ag-Cu-Ni alloys.