Al-Mg合金熔体快速凝固过程中微观结构演化机理的模拟研究

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 关键词： Al-Mg合金熔体 快速凝固过程 分子动力学模拟 微观结构

Simulation of evolution mechanisms of microstructures during rapid solidification of Al-Mg alloy melt

The rapid solidification of Al₅₀Mg₅₀ 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 Faber-Ziman partial structure factors are in good agreement with the experimental results. The Al₅₀Mg₅₀ alloy melt possesses heredity. The Al₅₀Mg₅₀ 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 Al₅₀Mg₅₀ 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-rang-order regions. But it can not be described with the Bernal model.