Dependence of diffusion on the alloy composition in ZrTiCuNiBe bulk glasses

The diffusion coefficients of impurities in ZrTiCuNiBe-bulk glasses with di fferent Be/Ti ratio were measured ill the temperature range around the glas s transition using the technique of secondary loll mass spectrometry. Durin g long rime annealing, the Zr41Ti14Cu12.5Ni10Be22.5 glass (V1) undergoes an amorphous decomposition and the diffusion coefficients decrease by more th an one order of magnitude. Two glasses, Zr41Ti8.7Cu12.5Ni10Be27.8 (D1) and Zr41Ti16.5Cu12.5Ni10Be20 (D2), which were produced to represent the decompo sition phases of V1, also show a tendency of decomposition and time-depende nt diffusion coefficients. Diffusion measurements performed at short anneal ing times yield only small differences between the temperature dependencies of the diffusion coefficients of the different impurities in all alloys. I n general, the size rule is obeyed, i.e, the activation energies of diffusi on 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 d iffusion is observed. (C) 2001 Elsevier Science B.V, All rights reserved.