Structural evolution of Zr60Al15Ni25 bulk metallic glass in supercooled liquid region

Atomic structures of a bulk metallic glass Zr60Al15Ni25 at some elevated temperatures in the supercooled liquid region as a function of annealing time have been studied by x-ray diffraction. A fast xray measurement apparatus adopting the geometry of the Debye-Scherrer camera in combination with an imaging plate has been exclusively built for these in-situ measurements. A whole diffraction profile of very good counting statistics is obtained for a shorter time (congruent to 300s). In the measurements at 693K below the glass transition temperature (T-g), the atomic structure shows little change even for a long annealing time. In contrary, it shows a faster change in the supercooled liquid towards an atomic structure expected from the crystalline phase. A couple of structural features have been noted in the supercooled liquid. About 7% increase in the total coordination number around Zr and an increase in a fraction of Al around Zr in accompanied with a decrease in a fraction of Ni have been observed.