Rapidly achieving high-performance joining of single crystal superalloy and powder metallurgy superalloy via partial transient liquid phase diffusion bonding

A rapid and high-performance partial transient liquid phase diffusion bonding process has been proposed for the DD5 single crystal superalloy and the FGH96 P/M superalloy via a mixture of Ni-Ti alloy and FGH96 P/M superalloy powders as interlayer. During the bonding process, isothermal solidification and homogenization of the joint were achieved through a rapid diffusion mechanism of short-range and large-area between the liquid phase of Ni-Ti and the FGH96 particles and the base material. When bonded at 1170 degrees C only for 60 min of the holding time, isothermal solidification and homogenization of the joints were completed. The isothermal so-lidification joint consisted of a polycrystalline zone with gamma/gamma ' structure similar to that of FGH96 and an epitaxial growth zone (EGZ) derived from DD5. Compared with traditional brazing and transient liquid diffusion bonding process (TLP), no brittle compounds and eutectics of Si and B were presented in the joint, which ensured the joint with excellent mechanical properties. With the increase of holding time, both the tensile strength and elongation was significantly increased on account of the reduction of eta-Ni3Ti. When the joints were bonded at 1170 degrees C for 60 min, the elevated temperature strength of 650 degrees C reached 880.7 MPa, which was more than 80 % and 60 %o that of the DD5 and FGH96, respectively.