(沈阳工业大学 材料科学与工程学院，沈阳 110870)
摘 要: 为了研究Mg2Si含量不同的Al-Mg2Si复合材料中相成分的变化规律，利用原位内生工艺制备Al-15%Mg2Si、Al-20%Mg2Si、Al-25%Mg2Si和Al-30%Mg2Si这4种不同成分的复合材料，并通过实验和理论模拟相结合的手段来分析。SEM、EDS、DSC以及XRD定性和定量分析的实验结果表明，4种成分Al-Mg2Si复合材料中主要含α(Al)相和Mg2Si相，但Mg2Si实测的质量分数均比理论值小。利用基于密度泛函理论的第一性原理的模拟方法，计算Al-Mg2Si复合材料中可能相(Mg2Si和Mg17Al12)的结构稳定性和电子结构。结果表明：Mg2Si相的键合能力、合金化能力和晶体结构稳定性均优于Mg17Al12相的。所以，Mg2Si相是Al-Mg2Si复合材料中优先形成的结构稳定的化合物，而Mg2Si相含量减少可能是由于Mg元素烧损引起的，适当增加Mg加入量能有效减小实验误差。
关键词: 第一性原理；差示扫描量热；定量分析；电子结构；差分电荷密度
（School of Material Science and Engineering, Shenyang University of Technology, Shenyang 110870, China）
Abstract:The Al-Mg2Si as-cast in-situ composites with different amounts of Mg2Si were fabricated, such as Al-15%Mg2Si, Al-20%Mg2Si, Al-25%Mg2Si and Al-30%Mg2Si, and the changes of phase composition in Al-Mg2Si composite were then analyzed by combination of experiments and theoretical simulations. Microstructural examinations were assessed by the use of SEM, EDS, DSC and XRD. The results show that phase composition of the four different components of Al-Mg2Si composite is α(Al) phase and Mg2Si phase; and content of Mg2Si phase in the four different components is less than theoretical value. Structural stabilities and electronic structures of possibly emerging phase (Mg2Si phase and Mg17Al12 phase) in Al-Mg2Si composite were investigated by first-principles program based on density functional theory. The calculation results reveal that both Mg2Si and Mg17Al12 can form stable compounds, whereas Mg2Si phase has stronger bonding ability and alloying ability as well as the higher structural stability. Therefore, Mg2Si is the priority stable phase in Al-Mg2Si composites, while the decrease of mass fraction of Mg2Si phase turns out to be the burning loss of magnesium, and increasing the additions of magnesium can reduce the experimental error effectively.
Key words: first-principles; DSC; quantitative analysis; electron structure; charge density difference
