中文摘要：

利用高温液态X射线衍射研究了纯铁,Fe-1C和Fe-1Si合金在约1550℃及Fe-1C-xSi(质量分数,%)合金从熔点附近至1560℃的液态结构.结果表明:与纯铁的最近邻距离r1=0.259 nm和配位数N1=10.5相比,液态Fe-1C合金的r1和N1略有增加.而液态Fe-1Si合金的r1和N1却略微减小.在1560-1470℃,液态Fe-1C-1Si合金的r1=0.254-0.250 nm,明显低于液态Fe-1C合金和Fe-1Si合金的r1值.从1560℃降温至1530℃时,Fe-1C-1Si合金的r1值减少,而N1由10.3剧增至11.8,并且在熔点以上不高的温度保持12.0不变.分析表明:在液态二元系中,C和Si以不同形式存在;而在三元系中,C和Si对纯铁的液态结构具有复杂的影响.Fe-1C-1Si合金在1560-1530℃范围内存在由δ相向γ相的转变,而这种相变随Si含量的增加向低温区域扩展,在Si含量为4%时熔体为单一的δ相,这主要是Si元素抑制γ相区而扩展δ相区产生的.

英文摘要：

The liquid structures of pure iron, Fe-1C, Fe-1Si at about 1550 degreesC and Fe-1C-xSi alloy in a range from melting point to 1560 degreesC were studied by high temperature X-ray diffractometer. Compared with the nearest neighbor distance r(1) =0. 259 nm and the first coordination number N-1 = 10.5 for pure liquid iron, there is a bigger r(1) and N-1 for Fe-1C alloy, but a smaller r(1) and N-1 for Fe-1Si alloy. There is a bigger decrease of r(1) for Fe-1C-1Si alloy than those of pure liquid iron and binary alloys. Cooling from 1560 degreesC to 1530 degreesC for Fe-1C-1Si alloy, an abrupt increase of N-1 from 10.3 to 11.8 exists in the liquid, which maintains at about 12.0 near the melting point. The existence forms for C and Si in binary liquids are different. In Fe-1C-1Si liquid, a phase transition of delta --> gamma exists in the temperature range from 1560 degreesC to 1530 degreesC, which extends to lower temperature range with increasing of Si content, and there is a single 6 phase existing in the melt at about 4%Si. The appearance of the phase transition is mainly caused by silicon atoms.