Impurity diffusion characteristics were determined for relaxed amorphous alloy samples at temperatures ranging from 573 to 694K. It was observed that there was no systematic dependence of the diffusivity upon the 2 different methods of surface preparation (table 33); thus proving the non-existence of crystalline particles in the surface layers of relaxed amorphous ribbons. The data could be described by the expression:
D (m2/s) = 1.1 x 10-6exp[-1.80(eV)/kT]
No difference between Fe impurity diffusion and Co diffusion could be detected in the relaxed amorphous alloy. This suggested that Fe and Co diffused via the same mechanism.
J.Pavlovský, J.Cermák: Scripta Metallurgica et Materialia, 1994, 30[10], 1317-20
Table 33
Diffusivity of Fe in Co79Nb14B7
Temperature (K) | Surface Treatment | D (m2/s) |
694 | polished | 7.07 x 10-20 |
669 | polished | 3.82 x 10-20 |
669 | sputtered | 2.74 x 10-20 |
640 | polished | 5.77 x 10-21 |
640 | sputtered | 8.02 x 10-21 |
603 | polished | 8.41 x 10-22 |
603 | sputtered | 1.28 x 10-21 |
573 | polished | 1.28 x 10-22 |
573 | sputtered | 1.21 x 10-22 |