SOME CORRELATIONS OBSERVED FOR DIFFUSION IN AMORPHOUS TI60NI40 AND FE40NI40B20 ALLOYS

A systematic study pertaining to the diffusion of several impurity ato ms (B, Be, Fe, Cu, Si and Ti) in relaxed amorphous Ti60Ni40 and Fe40Ni 40B20 alloys was carried out in the temperature range 573-690 K using the technique of secondary ion mass spectrometry (SIMS) for concentrat ion depth profiling. Based on the results of this study the following observations were made: (i) the smaller atoms diffused much faster tha n the bigger atoms, suggesting a correlation between the diffusion coe fficient, D, and the diffusant atom size; (ii) a trend of increasing e ffective activation enthalpy, Q, with an increase in the diffusant ato m size was apparent; and (iii) the values of the prefactor, D0, and th e effective activation enthalpy, Q, followed the relation D0 = A exp(Q /B), where A and B are empirical values which uniquely characterize th e amorphous materials.