摘要
采用基于密度泛函理论的赝势平面波法,计算Al-Sc的4个稳定相的电子结构,分析其成键情况,并采用基于第一性原理的热力学计算公式,计算各相的生成焓、结合能、德拜温度、体弹模量和自由能。结果表明:Al-Sc金属间化合物在费米面以下,主要通过Al3s-Sc3d和Al3p-Sc3d杂化成键,在费米面以上则以Sc3d成键为主;随着Al在各相中所占比例的增大,体系中共价性增大,稳定性提高,且Al2Sc与Al3Sc在低能级区成键电子较多,结构较为稳定。在4个化合物中,0K时合金化形成能力最强的是Al2Sc(H0=-52.02kJ/mol),最弱的是AlSc2(H0=-35.93kJ/mol)。自由能计算所得曲线表明:Al2Sc的结构稳定性最好,AlSc2的最差;随着温度的升高,晶体稳定性都降低。所有热力学计算值与试验值吻合良好。
Based on the density functional theory（DFT）,the plane-wave pseudopotential method was used to calculate the electronic structures of four stable phases for Al-Sc alloys.The bonding situation was analyzed,and the formation enthalpy,binding energy,Debye temperature,bulk modulus and free energy of each phase were calculated by the thermodynamic calculation formula based on the first-principle.The results show that,under the Fermi energy,the bonds of each phase are mainly mixed by Al 3s-Sc 3d and Al 3p-Sc 3d;over the Feimi energy,those bonds are mainly contributed by electrons of Sc 3d.As the Al content increases,the covalent and stability of the system increase,and Al2Sc and Al3Sc are the stable structures by the more bonding electrons in low-energy area.Among the four crystals,the alloy-forming ability of Al2Sc（H0=-52.02 kJ/mol） is the greatest,that of the AlSc2（H0=-35.93 kJ/mol） is the lowest.The free energy curves show that the crystal stability of Al2Sc is the highest,AlSc2 is the most unstable;and the stabilities of the four crystals are all reduced with increasing temperature.All the calculations data agree well with the experimental data.
出处
《中国有色金属学报》
EI
CAS
CSCD
北大核心
2010年第5期946-953,共8页
The Chinese Journal of Nonferrous Metals
基金
湖南省自然科学基金资助项目(07JJ3102)
长沙市科技计划资助项目(k0902132-11)
关键词
Al-Sc金属间化合物
电子结构
稳定性
热力学性能
自由能
密度泛函理论
赝势平面波法
Al-Sc intermetallics compounds
electronic structure
stability
thermodynamic properties
Gibbs free energy
density functional theory
plane-wave pseudo-potential method
