X-RAY DIFFRACTION STUDY OF AL-GE MELTS IN A WIDE RANGE OF TEMPERATURES AND CONCENTRATIONS
O. M. Yakovenko, V. P. Kazimirov, A. S. Roik, N. V. Golovataya, S. P. Yaltanskii†, V. E. Sokol’skii
Taras Shevchenko National University of Kyiv, Kyiv, Ukraine
Keywords: расплав Al-Ge, микрогетерогенная структура, рентгеновская дифракция, ближний порядок, Al-Ge melts, microheterogeneous structure, X-ray diffraction, short-range order
Abstract
An X-ray diffraction study is performed of the structure of Al-Ge melts containing 0 at.%, 10 at.%, 20 at.%, 30.3 at.%, 40 at.%, 50 at.%, 60 at.%, 70 at.%, 80 at.%, and 100 at.% Ge near the liquidus line at 1273 K. The melts containing 40 at.%, 70 at.%, and 80 at.% Ge are studied in the temperature range up to 1823 K. The structural factor (SF) curves of the melts have a shoulder on the high-angle side of the first maximum at contents above 20 at.% Ge; the position of the shoulder coincides with that on the SF curve of liquid germanium. An increase in temperature leads to gradual smoothening of the shoulder because of the increase in the structural homogeneity of the melts, which is attributed to the metallization of the residual covalent bonds between germanium atoms. The structure of the melts is found to be microheterogeneous for germanium contents above 20 at.%, which is due to the coexistence of microclusters of liquid germanium and those of the melt with 20 at.% Ge, which provides a satisfactory description of the experimental SF curves in the concentration range 20-100 at.% Ge at temperatures near the liquidus line.
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