Structure of Zr{sub}52Ti{sub}5Cu{sub}18Hi{sub}15Al{sub}10 Bulk Metallic Glass at Elevated Temperatures

摘要

The glass transition and the phase formation during crystallization of the Zr{sub}52Ti{sub}5Cu{sub}18Ni{sub}15Al{sub}10 bulk metallic glass were followed in situ by high-temperature X-ray diffraction using synchrotron radiation at the high energy beam-line BW5 (λ = 0.·0 nm) at the storage ring DORIS (HASYLAB, Hamburg). The experimental set-up enables to record intensities in transmission up to scattering vectors q of 200 nm{sup}(-1) with a measuring tune of 20 s per diagram. The crystallization starts with the formation of an extremely fine nanostructure followed by the transformation into tetragonal NiZr{sub}2-type crystals plus an unknown phase. Both phases are metastable and transform at about 1123 K into the stable equilibrium phases. The temperature dependence of the structure factor S(q) of the glass can be well described within the framework of the Debye theory. At the glass transition the first derivative dS(q)ldT changes. A Debye temperature Θ = 412 K was estimated for the glassy, and Θ = 162 K for the liquid state of the Zr{sub}52Ti{sub}5Cu{sub}18Ni{sub}15Al{sub}10 alloy. The short-range order of the glass, of the supercooled liquid state, and of the equilibrium melt at T= 1193 K is found to be quite similar.