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Microstructure of a transient liquid phase (TLR) bonded joint between single crystal DD98 and polycrystalline K465 superalloys was investigated by scanning electron microscopy, transmission electron microscopy and X-ray diffraction techniques. After bonding at 1190 degrees C for 2 h, many phases formed in the centerline of the bonding zone due to an incompletely solidified liquid interlayer. There are script-like, tree-like and blocky compounds besides solid solution gamma phase in this region. The script-like phase is CrB boride that is rich in Cr, the tree-like compound rich in Ni is M(23)B(6) with FCC structure, and the blocky phase enriched in Ti, Ta, and Nb, is MC carbide that resulted from the interdiffusion of C atoms between dissimilar base metals. After TLP bonding, many blocky and fine M(6)C particles rich in Cr and W appeared in the diffusion zone of the K465 side. A number of blocky and platelet M(3)B(2) borides rich in W, Cr and Mo precipitated in the diffusion zone of the DD98 side. (C) 2011 Elsevier Inc. All rights reserved.