Abstract: Using hightemperature θθ Xray diffractometer,the liquid structure of Fe68Si32 alloy was investigated and the structure factor, radial distribution function, the nearest neighbor distance and coordination number were obtained. In the temperature range of 1250～1450 ℃ the nearest neighbor distance and coordination number of the alloy are 0.259～0.260 nm and 10.3(±0.2), respectively. A visible prepeak atQ=15.5 nm－1 in the structure factor S(Q) of liquid Fe68Si32 alloy is observed. According to the characters of prepeak, an atom model of liquid Fe68Si32 alloy was constructed, namely, ordered bcc Fe3Si clusters form a Fe3Si fcc superstructure unit(DO3) with a shared face. The results of Gaussian separation of RDF for Fe68Si32 alloy at 1250 ℃ agrees well with that of Fe3Si superstructure. The prepeak is related to the correlation between silicon atoms in the superstructure. The Xray diffraction of solid Fe68Si32 alloy showed the existence of Fe3Si phase in the alloy and the peaks agree with that of S(Q), which means the correlation of structure between liquid and solid Fe68Si32 alloy.

Key words: Liquid and solid Fe₆₈Si₃₂ alloy, Structure factor, Pre-peak, X-ray diffraction