Investigation of the particular features of the structure factor of liquid Al-based alloys
Investigation of the particular features of the structure factor of liquid Al-based alloys
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DOI：
10.1016/j.molliq.2011.04.010
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发表时间：
2011-06
影响因子：
6
通讯作者：
O. Roik;A. Anikeenko;N. N. Medvedev-N.
中科院分区：
文献类型：
--
作者：
O. Roik;A. Anikeenko;N. N. Medvedev-N.
用反蒙特卡罗(RMC)和分子动力学(MD)模拟方法研究了铝与过渡金属(Al-TM)二元和三元液态合金的结构。讨论了它们的结构因子的两个明显特征：第二峰的肩部和主峰左侧的前峰。在模型中选择了形状接近正四面体(准正四面体)的相邻原子的四元组(Delaunay单形)并进行了检验。它们结合成不同形态的簇(多四面体)形成多四面体有序(PTO)，并且在我们的合金中没有类似于二十面体的这些四面体的致密簇。讨论了结构因子的第二峰特征与PtO有关，而不需要解释液态合金中存在二十面体短程有序(ISRO)。预峰是由化学短程有序(CSRO)引起的。在我们的模型中，它主要是在原子的子系统上观察到的，而原子的子系统与多面体的子系统是互补的。在单原子液体模型上对CSRO进行了模拟。模拟中得到了一个新的预峰长度标度。
We study the structure of liquid binary and ternary alloys of aluminum with transition metals (Al–TM) obtained by Reverse Monte Carlo (RMC) and Molecular Dynamics (MD) simulation methods. Two distinctive features of their structure factor are discussed: the shoulder on the second peak and the prepeak on the left side of the main peak. The quadruples of mutually neighboring atoms (Delaunay simplexes) with a shape close to a regular tetrahedron's (quasi-regular tetrahedra) have been selected in the models and examined. They combine into clusters of different morphology (polytetrahedra) forming a polytetrahedral order (PTO), and there are no compact clusters of these tetrahedra similar to icosahedron in our alloys. It is discussed that the second peak feature of the structure factor is associated with PTO, and does not require for its explanation the presence of icosahedral short-range order (ISRO) in the liquid alloys. The prepeak is caused by the chemical short-range order (CSRO). In our models it is observed mainly on the subsystem of atoms which is complementary to the subsystem of the polytetrahedra. Simulation of the CSRO was performed on a model of monatomic liquid. A new length scale responsible for the prepeak has been obtained in this simulation.