DEVELOPMENT OF LOW TEMPERATURE BRAZING ALLOYS FOR TITANIUM HONEYCOMB SANDWICH MATERIALS

An investigation was made to develop a process for brazing Ti honeycomb sandwich compatible with its aging cycle (below 1100 F). Also, the brazed joints were to be capable of service up to 850 F. Initial tests indicated that wetting and flow of the braze alloys were negligible on Ti-6Al-4V at 1050 F; however, by increasing the time at temperature (to approximately 1 hr or more) good wetting and flow occurred. Further investigation revealed that small additions of Ti to the braze alloys permitted brazing Ti-6Al-4V within 3 to 5 min at 1050 F. Preplaced Ti powder at the joints to be brazed also increased wetting and flow and reacted with the braze alloys to raise the remelt temperature of the joints appreciably. Joints brazed with Au-Sn-Ti showed good resistance to corrosion and high temperature air oxidation; however, strength and ductility were low. (Author)