中文摘要：

采用分子动力学方法对Al50Mg50合金熔体的快速凝固过程进行了模拟,并采用双体分布函数、键型指数法和原子团类型指数法等方法,从微观结的不同层面对Al-Mg合金熔体快速凝固过程中微观结构的演化机理进行了深入的分析研究.结果表明：本模拟所获得的Faber-Ziman偏结构因子与实验结果符合较好.Al50Mg50合金熔体具有遗传性,在快速凝固过程形成了非晶态结构,其中二十面体短程序结构对非晶态结构的形成起决定性作用.基于原子团类型指数法的团簇分析表明,Al50Mg50非晶态合金的微观结构由许多不同结构类型的短程有序结构单元构成,其中二十面体基本原子团是其主要的短程有序结构单元,短程有序区包含各种不同尺寸的团簇结构.其微观结构不能采用Bernal模型来表征.

英文摘要：

The rapid solidification of Al50 Mg50 alloy melt has been simulated by using molecular dynamics method, and the evolution mechanism of microstructures at different levels during the rapid solidification process have been deeply studied with the pair distribution function, the bond-type index method and the cluster-type index method. It is demonstrated that the simulated FaberZiman partial structure factors are in good agreement with the experimental results. The Al50 Mg50 alloy melt possesses heredity. The Al50 Mg50 amorphous structure is formed during the rapid solidification process, and the icosahedron short-rang-order structure plays a critical role in the formation of amorphous structure. The atomic cluster analyses based on the cluster-type index method shows that the microstructures of Al50 Mg50 amorphous alloy is built from some different types of short-rang-order structures, and the icosahedron is the main short-rang-order structure. There are various cluster structures with different sizes in the short-rangorder regions. But it can not be described with the Bernal model.