Interdiffusion experiments were performed between various 2-phase Ni–Al alloys. A method was described for estimating the tracer diffusion coefficient of one of the constituents in a binary alloy, knowing the tracer diffusion coefficient of the other species. The procedure was based upon the so-called Darken-Manning analysis. The tracer diffusion coefficient of Al was determined in this way in Ni3Al:

D (m2/s) = 5.05 x 10-7exp[-243(kJ/mol)/RT]

The present results were compared with published data. The values for the self-diffusivity of Al, as calculated from interdiffusion experiments, gave consistent results. All of the measurements supported the theory that diffusion of minor element occurred via a vacancy mechanism in Ni3Al.

Intrinsic Diffusion in Ni3Al System. Cserháti, C., Paul, A., Kodentsov, A.A., van Dal, M.J.H., van Loo, F.J.J.: Intermetallics, 2003, 11[4], 291-7

Figure 5

Diffusion of Al and Fe in a Ni75.5Al24.5/Ni75.0Al19.0Fe6.0 couple

White circles, i = Fe; black circles, i = Al