(沈陽工業(yè)大學 材料科學與工程學院，沈陽 110870)
摘 要: 為了研究Mg2Si含量不同的Al-Mg2Si復合材料中相成分的變化規(guī)律，利用原位內(nèi)生工藝制備Al-15%Mg2Si、Al-20%Mg2Si、Al-25%Mg2Si和Al-30%Mg2Si這4種不同成分的復合材料，并通過實驗和理論模擬相結合的手段來分析。SEM、EDS、DSC以及XRD定性和定量分析的實驗結果表明，4種成分Al-Mg2Si復合材料中主要含α(Al)相和Mg2Si相，但Mg2Si實測的質(zhì)量分數(shù)均比理論值小。利用基于密度泛函理論的第一性原理的模擬方法，計算Al-Mg2Si復合材料中可能相(Mg2Si和Mg17Al12)的結構穩(wěn)定性和電子結構。結果表明：Mg2Si相的鍵合能力、合金化能力和晶體結構穩(wěn)定性均優(yōu)于Mg17Al12相的。所以，Mg2Si相是Al-Mg2Si復合材料中優(yōu)先形成的結構穩(wěn)定的化合物，而Mg2Si相含量減少可能是由于Mg元素燒損引起的，適當增加Mg加入量能有效減小實驗誤差。
關鍵字: 第一性原理；差示掃描量熱；定量分析；電子結構；差分電荷密度
（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
