Sodium compatibility of refractory metal alloy/304L braze joints

Technical Report · Tue May 01 04:00:00 EDT 1984

OSTI ID:6944365

Hosking, F M

Vacuum induction brazing of Mo, Re, Ta, and W aloys to 304L stainless steel with AWS BNi filler metals was investigated. Metal powder (BNi-5 and BNi-7) and metallic glass (BNi-3 and modified BNi-5) brazing alloys were evaluated. Excellent braze joints were obtained with the BNi-3 and modified BNi-5 metallic glass foils. Cracks and porosity were observed in the metal powder BNi-5 and BNi-7 brazes. The as-brazed, refractory metal/304L samples were also qualified in a sodium environment of 1073/sup 0/K (1472/sup 0/F)/130 hours/2 and 100 ppM oxygen concentration. There was no significant chemical corrosive attack observed on any of the sodium samples and weight changes were generally negligible. Braze separation along the refractory metal interface and crack growth in the filler metal, however, were observed in the metal powder brazes after the sodium exposures. As a result, the metal powder fillers were not recommended. A band of discontinuous voids in the metallic glass brazes near the refractory metal interface was also detected. Metallographic, thermal and microprobe analyses revealed that these voids were caused by a diffusion mechanism called Kirkendall porosity. Since the voids were not connected and would not provide a leak path, the metallic glass filler metals were recommended for brazing refractory metal alloys to 304L and for subsequent sodium exposures.

• Research Organization: Sandia National Labs., Albuquerque, NM (USA)
• DOE Contract Number: AC04-76DP00789
• OSTI ID: 6944365
• Report Number(s): SAND-84-0708; ON: DE84012877
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360101* -- Metals & Alloys-- Preparation & Fabrication
ALKALI METALS
ALLOY-TZM
ALLOYS
BRAZED JOINTS
CHROMIUM ALLOYS
CHROMIUM STEELS
CHROMIUM-NICKEL STEELS
COMPATIBILITY
CORROSION RESISTANCE
CORROSION RESISTANT ALLOYS
ELEMENTS
FILLER METALS
HEAT RESISTANT MATERIALS
HEAT RESISTING ALLOYS
IRON ALLOYS
IRON BASE ALLOYS
JOINTS
MATERIALS
METALS
MOLYBDENUM
MOLYBDENUM ALLOYS
MOLYBDENUM BASE ALLOYS
NICKEL ALLOYS
RHENIUM
RHENIUM ALLOYS
SODIUM
STAINLESS STEEL-304L
STAINLESS STEELS
STEELS
TANTALUM ALLOY-T111
TANTALUM ALLOYS
TANTALUM BASE ALLOYS
TITANIUM ALLOYS
TRANSITION ELEMENTS
TUNGSTEN
TUNGSTEN ALLOYS
VERY HIGH TEMPERATURE
WELDED JOINTS
ZIRCONIUM ALLOYS