Self-diffusion in the amorphous and supercooled liquid state of the bulk metallic glass Zr46.75Ti8.25Cu7.5Ni10Be27.5

Nickel and zirkonium self-diffusion in the amorphous and the supercooled li quid state of the bulk metallic glass Zr46.75Ti8.25Cu7.5Ni10Be27.5 has been investigated using the radiotracer method. Encompassing four orders of mag nitude in the diffusivity self-diffusion of Ni-63 cannot be fitted to a sin gle Arrhenius function. The deviation from an Arrhenius function is attribu ted to differences between the supercooled liquid and glassy state. This ex planation is supported by recent diffusion studies reported by other author s. Self-diffusion of the major component studied with the isotope Zr-95 is much slower compared to the above-mentioned measurements. We also performed high pressure experiments in the supercooled liquid state from which activ ation volumes for Ni-63 diffusion of about one mean atomic volume were dedu ced. This suggests that diffusion in the supercooled liquid state proceeds by a hopping process involving vacancy-like defects. (C) 1999 Elsevier Scie nce B.V. All rights reserved.