The invention relates to a low temperature diffusion welding method of tungsten alloy and tantalum alloy. The steps of the method include: (1) workpiece surface cleaning steps: the tungsten alloy and tantalum alloy are processed to a specified size, and the oxide layer and the middle layer-nickel foil to be welded surface are removed; (2) Workpiece assembly steps: place the middle layer - nickel foil between tungsten alloy and tantalum alloy to construct the welder workpiece; (3) Vacuum diffusion welding steps: put the welder parts into the vacuum diffusion welding furnace, heat and keep warm. When the heat preservation begins, apply axial pressure on the welder parts. After the heat preservation, remove the pressure and cool with the furnace. The invention can overcome the problem that the existing welding technology cannot realize high-quality diffusion welding of tungsten alloy and tantalum alloy at low temperature, especially suitable for reliable and precise diffusion welding between tungsten alloy and tantalum alloy at low temperature, and the tungsten and tantalum welding body prepared can be used in dynamic high pressure physics and nuclear fusion and other research fields.
Tantalum alloy with high density, high melting point, good corrosion resistance, excellent high temperature strength, workability, weldability and low plastic/brittle transition temperature, excellent dynamic mechanical properties and surface density, stable, high dielectric constant of the amorphous oxide film and other characteristics, widely used in electronic, chemical, aerospace, weapons, and other fields. So in order to more fully play their respective advantages of the high density tungsten alloy and tantalum alloy, in the high-tech fields such as aerospace, dynamic high-pressure physics, nuclear fusion, has important applications in areas such as weapons, and to adopt effective welding technology, to obtain high quality high density tungsten alloy and tantalum alloy welded joint of dissimilar metal materials.
Defects in direct welding joints of tungsten alloy and tantalum alloy lead to low corrosion resistance and reduced service life of materials. The welding strength was improved after the welding temperature was further improved, but the fracture toughness of the material was reduced due to the recrystallization and grain coarsening of W and Ta. The decrease of welding temperature will lead to the decrease of welding strength; At the same time, Ta begins to oxidize when heated to 200°C, and rapidly oxidizes above 500°C, and has the characteristics of absorbing hydrogen, oxygen and nitrogen. A small amount of gaseous impurities will have a strong impact on its organizational structure and mechanical properties.
