Abstract:Transient liquid phase (TLP) bonding technique was used in joining IC6 alloy, a newly developed Ni₃Al based intermetallic material. Studies were focused on the borides at the interfacial zone, which were formed through the diffusion of boron from the interlayer into the base metal during the bonding process. The morphology and microstructure of the borides were investigated, as well as their growth mechanism and microstructure evolution with increasing holding time. Both the needle-like and the blocky borides were testified by EDS and TEM as Mo₂NiB₂, with (110) and (211) as interfacial planes. The results show that the borides have some orientation relationship with that of the base metal, that is (211)_borides∥(111)_substrate,〈1^-11〉_borides∥〈12^-3〉_substrate. The growth of the borides is controlled by long-range diffusion of solute atoms. The borides are always enveloped by γ′-Ni₃ (Al, Mo) films, which would influence the growth behavior of the borides greatly.

Key words: transient liquid phase bonding; borides; Ni₃Al based alloys