Self-diffusion in pure Ni-rich samples was measured at 882 to 1374K by using 63Ni radiotracer, serial sectioning and liquid scintillation counting techniques. It was found that the product of grain-boundary diffusivity and grain boundary width was described by:

D (m3/s) = 3.27 x 1013exp[-168(kJ/mol)/RT]

Grain boundary diffusion was also investigated in B-doped (0.24at%) Ni-rich samples at 882 to 1352K. These results could be described by:

D (m3/s) = 1.24 x 1012exp[-187(kJ/mol)/RT]

The increase in activation enthalpy, and the decrease in the pre-exponential

product of grain-boundary diffusivity and grain boundary width, as a result of B-doping was attributed to the segregation of B in the Ni3Al grain boundaries.

S.Frank, J.Rusing: Intermetallics, 1996, 4[8], 601-11