Tracer diffusion coefficients were measured for large- and small-sized impurities in several bulk metallic glass compositions. Molecular beam deposition was used to grow thin films, and secondary ion mass spectrometry was used to determine the concentration versus depth profiles of several tracers. A dependence of the atomic mobility of the tracer upon its size was found. The presence of Al reduced the diffusion coefficients in general, with a sharper decrease in the case of small-sized tracer. The results suggested the existence of 2 different diffusion mechanisms.

Diffusion in Amorphous NiZrAl Alloys. S.Flege, U.Fecher, H.Hahn: Journal of Non-Crystalline Solids, 2000, 270[1-3], 123-8

[749] Ni54Zr46: Au, Hf Diffusion

Tracer diffusion measurements were performed, in vacuum and under high hydrostatic pressures, using amorphous samples. A marked structural relaxation effect was observed for both solutes, and led to a decrease in the diffusivity with annealing time. The relaxation time was nearly the same in both cases. For well-relaxed samples, the results could be described by:

Au:     D (m2/s) = 1.9 x 10-9 exp[-1.65(eV)/kT]

Hf:     D (m2/s) = 2.8 x 10-9 exp[-1.78(eV)/kT]

The activation volumes were equal to 0.51 and 0.52 atomic volumes, respectively.

A SIMS Investigation of Tracer Diffusivities in an Amorphous Ni54Zr46 Alloy. Y.Loirat, J.L.Bocquet, Y.Limoge: Journal of Non-Crystalline Solids, 2000, 265[3], 252-64

Table 84

Diffusivity of Ni in Ni-Fe-Al Alloys

continued

Table 84 (continued)

Diffusivity of Ni in Ni-Fe-Al Alloys