TLP Weldability of Nickel-Base Superalloys

The TLP (Transient Liquid Phase) weldability of nickel-base heat-resistant alloys (Hastelloy X, Inconel X-750 and Udimet 500) have been studied by microscopy, electron-probe-microanalysis, tensile tests and stress-rupture tests of the joints.The major cause to restrict the TLP weldability was the formation during welding of a continuous array of stable Ti, Al and/or Nb compounds at the joint interface, which produce a weak plane joint grain boundary. In order to prevent this phenomenon, it was found important for interlayer alloys to melt moderately the base metal surface at the joint interface. For this purpose it was indicated that such interlayer alloys as including both boron and silicon which lower the melting point of the interlayer were more effective for TLP welding.