Dependence of diffusion on the alloy composition in ZrTiCuNiBe bulk glasses

The diffusion coefficients of impurities in ZrTiCuNiBe-bulk glasses with different Be/Ti ratio were measured in the temperature range around the glass transition using the technique of secondary ion mass spectrometry. During long time annealing, the Zr41Ti14Cu12.5Ni10Be22.5 glass (V1) undergoes an amorphous decomposition and the diffusion coefficients decrease by more than one order of magnitude. Two glasses, Zr41Ti8.7Cu12.5Ni10Be27.8 (D1) and Zr41Ti16.5Cu12.5Ni10Be20 (D2), which were produced to represent the decomposition phases of V1, also show a tendency of decomposition and time-dependent diffusion coefficients. Diffusion measurements performed at short annealing times yield only small differences between the temperature dependencies of the diffusion coefficients of the different impurities in all alloys. In general, the size rule is obeyed, i.e. the activation energies of diffusion increase with increasing atom size. The Arrhenius curves are not linear, indicating a significantly higher activation energy above about 580 K than below this temperature. No systematic effect of glass composition on the diffusion is observed.