DIFFUSION OF CU AND TI IN AMORPHOUS FE40NI40B20

The diffusion coefficients of Cu and Ti in the amorphous alloy Fe40Ni40B20 are measured in the temperature range 573 to 645 K by using the technique of secondary ion mass spectrometry (SIMS). The measurements are carried out on the pre-relaxed alloy specimens and the diffusion coefficients are found to lie in the range 3.0 x 10(-24) to 9.0 x 10(-21) m2 s-1. The temperature dependence of the measured diffusion coefficients is found to be Arrhenius in nature yielding the values of the activation energy as (2.73 +/- 0.27) and (3.82 +/- 0.37) eV atom-1 for the diffusion of Cu and Ti, respectively. The corresponding values of the pre-exponential factors are 1.3 x 10(1 +/- 2.2) and 8.5 x 10(8 +/- 3.0) m2 s-1. A comparison with other reported data on diffusion in this alloy is suggestive of a possible size dependence of diffusivity in this alloy.