Self-diffusion in Zr ₅₅ Al ₁₀ Ni ₁₀ Cu ₂₅ and Pd ₄₀ Cu ₃₀ Ni ₁₀ P ₂₀ bulk metallic glass

Self-diffusion coefficients of Ni in Zr ₅₅ Al ₁₀ Ni ₁₀ Cu ₂₅ and of Ni and Pd in Pd ₄₀ Cu ₃₀ Ni ₁₀ P ₂₀ bulk metallic glass below and above the glass transition temperature T _g have been measured with an ion-beam sputter-sectioning technique using the radioactive isotope ⁶³ Ni and ¹⁰³ Pd. The diffusion coefficients in the supercooled liquid region are much higher than those extrapolated from low temperature data in the amorphous region. The temperature dependence of the diffusion coefficients exhibits non-Arrhenius behaviour in the supercooled liquid phase. Such a deviation from the Arrhenius plots is interpreted by a cooperation of moving tracer atom with the surrounding atoms. The difference of the diffusion behaviour in between Zr-Al-Ni-Cu and Pd-Cu-Ni-P glasses is attributed to the different structural stability of both glasses.