摘要
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 .
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.
出处
《化学学报》
SCIE
CAS
CSCD
北大核心
2002年第2期287-292,共6页
Acta Chimica Sinica
基金
国家自然科学基金 (No .5 0 0 710 2 8)
山东省自然科学基金 (No .L2 0 0 0F0 1)资助项目
