液体和非晶态NiAl3合金结构的从头算分子动力学模拟

应用从头算分子动力学方法模拟了液体以及淬冷形成的NiAl₃合金体系,得到了它们的对相关函数、结构因子、键对分析信息.结果分析表明,在淬冷条件下得到的体系呈现非晶态性质,且非晶态结构类似于液态NiAl₃合金的结构,可以用液体结构近似描述非晶态性质.还进行了电子结构分析,得到液体NiAl₃合金的电子态密度和电荷分布.在液体镍铝合金中,镍为电子受体,部分电子由铝向镍转移,支持了Candy等人的XPS实验结果.镍铝间强烈作用,形成带有弱共价键性质的金属键.镍在合金中相当分散,这能部分解释由淬冷形成的NiAl₃合金制得的骨架镍催化剂活性增强的原因.

Ab initio Molecular Dynamics Simulation of Structures of NiAl3 Alloys in Liquid and Amorphous Phase

Liquid and rapidly quenched NiAl 3 alloys were simulated by ab initio molecular dynamics. The system properties such as pair correlation function, structure factors, bond pair analysis, electronic density of states and population analysis have been got. The results show that the amorphous alloys can be obtained by quenching rapidly and their structure is similar to that of liquid alloys, and the amorphous properties can be approximately described by means of the structure of liquid alloys. Electronic structure analysis indicates that the electronic charge transfers from Al to Ni, which supports the XPS experiment of Candy et al. Meanwhile, there are strong interactions between Ni and Al and the formed metallic bonds exhibit weak covalent property. The observed increased reactivity of skeletal Ni catalyst might be attributed to the greater dispersion of Ni atoms in amorphous NiAl 3 alloys than in liquid phase.