Abstract θ-Al13Fe4 forms as a primary Fe-intermetallic compound (Fe-IMC) in the casting processes of most Al alloys. Si is added to Al alloys to improve the mechanical performance of products. Fe-IMCs including (Si doped) θ-Al13Fe4 have nontrivial impacts on the mechanical performances of the solidified Al-based components. Here, we investigate systematically Si solution in θ-Al13Fe4 using ab initio density functional theory (DFT). We reveal that Si prefers substitution on two Al sites (Al9 and Al8) in θ-Al13Fe4, forming θ-Al70(Si,Al)IX4(Al,Si)VIII4Fe24 (the Roman numerals represent the Al sites (Grin et al., 1994) [13]). The calculations identify a linear relation between the lattice parameters of the unit cell and the Si content. The knowledge obtained here is useful to get insight into the formation and structural and chemical properties of the Fe–Al–Si intermetallic compounds and to optimize the microstructures and properties of the solidified Al based alloys.

中文翻译：

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第一性原理在 θ-Al13Fe4 中的 Si 溶液

摘要 θ-Al13Fe4 在大多数铝合金的铸造过程中作为主要的铁金属间化合物 (Fe-IMC) 形成。在铝合金中添加硅以提高产品的机械性能。包括（Si 掺杂）θ-Al13Fe4 的 Fe-IMC 对凝固的铝基部件的机械性能具有重要影响。在这里，我们使用 ab initio 密度泛函理论 (DFT) 系统地研究了 θ-Al13Fe4 中的 Si 溶液。我们发现 Si 更喜欢在 θ-Al13Fe4 中的两个 Al 位点（Al9 和 Al8）上进行置换，形成 θ-Al70(Si,Al)IX4(Al,Si)VIII4Fe24（罗马数字代表 Al 位点（Grin 等人， 1994) [13])。计算确定了晶胞的晶格参数和 Si 含量之间的线性关系。