An advanced technology for joining powder metallurgy (P/M) superalloy and single crystal (SC) superalloy is highly needed for fabricating a high-strength turbine bladed disk and the joints must meet the requirements of harsh working conditions such as long service time, high temperature and high pressure environments.Brazing, due to its simplicity, small capital investment and potential as a mass-production process,is a suitable joining method for dissimilar materials and complex aero-engine structures.The main limitation of brazing for joining P/M superalloy to SC superalloy is finding proper brazing filler metals that have desirable properties.In the present paper, P/M superalloy FGH96 and SC superalloy DD6 were joined together using Ni-Cr-B brazing alloy.The microstructure of the joint brazed at 1120℃ for 10 min showed that massive Ni3B phase was formed in the central part of the brazing seam.In the FGH96 matrix near the brazing seam, a small bright phase which contained some element B, Cr, Mo, W distributed along with grain boundary forming (Mo,W)B compounds.The joints were subjected to a diffusion heat treatment at 1000℃ for 1 h, 4 h and 16 h,respectively.The results showed that the diffusion depth of B is increased from 80 μm at 1000℃/1 h to 140 μm at 1000℃/16 h.In addition, the bright phase was refined obviously, indicating the homogenization of the joint microstructure.Compared with the heat treatment for 1 h and 4 h, the strength of the joints treated for 16 h was increased remarkably from 604~630 Mpa to 913 Mpa.