【摘要】 铝硅合金具有质轻、耐磨等优点,是重要的发动机缸体材料.铝硅合金主要以共晶结构存在,对铝硅晶体结构的研究可以帮助我们了解其成键性质及微结构.采用进化算法结合密度泛函理论研究了Al₄Si₃晶体的全局最稳定结构,结果表明,P4/MMM结构的结合能最大,为-29.05 eV.能带和电子局域函数表明Al₄Si₃晶体是零带隙导体,Si-Si、Al-Si键都是强共价键.对弹性模量和声子谱的分析也表明P4/MMM结构是动力学稳定的,还讨论了其力学性能.更多还原

【Abstract】 Aluminum-silicon alloy is an important engine block material with light weight and excellent wear resistance.Al-Si alloys exist mainly in eutectic structure.The investigations on the Al-Si crystal structures can help us understand the bonding properties and microstructures.This paper studies the global minima structure of Al₄Si₃ crystals by using evolutionary algorithm combined with the density functional theory.The results show that the P4/MMM structure has the largest binding energy of-29.05 eV.The electronic band structure and the electron localization function indicate that the Al₄Si₃ crystal is a zero band gap conductor,and the Si-Si,Al-Si bonds are strong covalent bonds.Analyses on the elastic modulus and phonon spectrum show that the P4/MMM structure is dynamically stable,and its mechanical properties are also discussed.更多还原