Al5Fe2合金熔体中程有序结构的研究

采用紧束缚原子间作用势，利用分子动力学模拟(MD)的方法研究了Al5Fe2合金熔体的微观结构，发现在结构因子的小角部分(Q=15.7nm^-^1)出现了一个明显的预峰(FSDP)，并得到X射线衍射实验的进一步印证，在实验测得的合金衍射图样中，液态衍射曲线与固态衍射曲线间存在着很好的对应关系，它们在小角部分都存在峰位，这表明Al5Fe2合金熔体与其固态在结构上存在着很大的相似性。通过对化学短程序参数α及Bhatis-Thornton(BT)结构因子的分析计算，发现熔体中存在较强的化学序，并认为正是这种化学序导致了中程有序结构(MRO)的产生。Faber-Ziman(FZ)偏结构因子的SFe-Fe(Q)和SAl-Fe(Q)在Q=15.7nm^-^1处分别存在最大值与最小值，也是熔体中存在着超结构的表征。同时，我们还给出了体系的配位数及代表中程有序的原子团簇的结构模型。

Study on medium-range order structure in liquid Al5Fe2 alloy

The molecular-dynamics (MD) simulation based on the tight-bind potential for a liquid Al 5Fe 2 has been carried out to invstigate the structure of medium-range order (MRO), combined with X-ray diffraction experiment. It is found that there exists an obvious prepeak in the low-Q domain (Q = 15.7 nm -1) of the structure factor. In the X-diffraction pattern, the liquid diffraction curve is corresponding with the solid diffraction curve. There exist the prepeaks for them in the low-Q domain, which shows that there is the comparability in the microstructure between them. Both the chemical order parameter and the Bhatis-Thornton (BT) partial structure factors indicate the existence of stronger chemical-range order (CRO) in the liquid alloy. The maximum and minimum in S Fe-Fe(Q) and S Al-Fe(Q) at Q = 15 7 nm -1 also show the existence of superstructure. We have also calculated the neighbor numbers of the system and given the structure model representing MRO.