Wide-gap brazing between K403 and DZ4 superalloys

The wide-gap brazing between K403 and DZ4 superalloys was investigated by using two tungsten-containing filler metals (N171 and N300) and Rene'95 superalloy powder. The results show that the wide-gap brazing between K403 and DZ4 could be realized by filling the joint gap with Rene'95 powder of proper particle size in advance. The post-brazing diffusion treatment at high temperature for a long time could obviously improve the joint microstructures and prevent the remelting of the wide-gap joints during the solution treatment. However, in order to prevent the phenomenon that the superalloy powder is excessively dissolved by the filler metal, the joints should be diffusion-treated first at a lower temperature, and then at high temperature. The joints brazed with N300 filler metal and Rene'95 powder can possess good mechanical properties at high temperature. After being diffusion-treated, the tensile strength of the joints at 900°C reaches 92% of that of casting K403 base metal, and the stress-rupture life time under 980°C/126 MPa is 135 h. After being solution-treated, the tensile strength of the joints at 900°C can surpasses that of casting K403 base metal (i.e. 677 MPa), and the stress-rupture life is also raised slightly.