二元液态金属Cu-Ni和Ag-Cu凝固过程的分子动力学模拟研究

用Quantum Sutton-Chen多体势对Ag6Cu4和CuNi液态金属凝固过程进行了分子动力学模拟研究.在冷却速率2×1012到2×1014K/s范围内,CuNi总是形成fcc晶体结构,而Ag6Cu4总是形成非晶态结构.考虑到CuNi及AgCu中原子半径之比分别为1.025和1.13,那么模拟结果证实了原子的尺寸差别是非晶态合金形成的一个主要影响因素.此外采用键对及原子多面体类型指数法对凝固过程中微观结构组态变化的分析,不但能说明二十面体结构在非晶态合金形成和稳定性中所起的关键作用,又有助于对液态金属的凝固过程、非晶态结构特征的深入理解.

Molecular-dynamics simulations of the solidification processes of binary liquid metals: Cu-Ni and Cu-Ag

A molecular dynamics (MD) simulation study has been performed for the solidification processes of binary liquid CuNi and Ag 6Cu 4 alloys by adopting the quantum Sutton Chen many body potentials. It is demonstrated that as cooling rates being in the range of 9×10 12 to 2×10 14 K/s, the CuNi alloy always forms a fcc crystal while Ag 6Cu 4 always forms a amorphous state. The former has radius ratio of 1.025(CuNi), while the latter (AgCu)-amorphous former has a ratio 1.13, this just confirm that the role of size mismatch is the main factor for forming amorphous. In addition, by using bondtype and polyhedron cluster type index methods to analyze the transformation of the microstructure, not only the key role of icosahedron in amorphous formation and stability can be explained, but also the solidification processes and the configuration characteristic of amorphous metals understood deeply.