In this study, the influence of different contents of Ba additions on the microstructure evolution, phase reaction characteristic, and mechanical property of Al–Mg–Si alloy was investigated. Microstructural characterization was conducted by means of scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS) facility, X-ray diffraction (XRD), and electron backscatter diffraction (EBSD). The mechanical property was examined using hardness test. The results revealed that cubic primary Mg₂Si crystals shaped by {100} facets with an average particle size of 35 μm were successfully fabricated through the addition of 0.2 wt. % Ba element to Al–Mg–Si melts. For the first time, it is revealed that the Al₄Ba compound can act as the nuclei for the primary Mg₂Si during solidification, which leads to the refining of the primary Mg₂Si particle size extensively. Furthermore, the formation of Al₂Si₂Ba and AlSiBa intermetallic compounds (IMCs) are liable for the Mg₂Si particle refinement; hence, the hardness of the alloy increased from 60.21 to 67.83 Hv. Besides, thermal analysis showed that the nucleation temperatures of the primary Mg₂Si phase increased with the addition of Ba. Ba additions perform a substantial role in determining the shapes of primary Mg₂Si crystals, which can be altered from coarse dendritic structure (0 wt. %) to crystals with a combination of eight {111} and four {100} facets (0.08 wt. %), then to truncated cube (0.1 wt. %), and finally to a cube fully bounded by {100} facets (0.2 wt. %) with increasing Ba concentrations. This study revealed that the growth process of the cubic primary Mg₂Si is due to the absorption and poisoning effect of Ba atoms, which leads to the fading of the growth rates of {100} faces of primary Mg₂Si and as a result the {100} faces are exposed. Furthermore, in the modified alloy, the skeleton-type growth process of the cubic primary Mg₂Si was found, in which growth steps with some hillocks were detected.

在这项研究中，研究了添加不同含量的Ba对Al-Mg-Si合金的组织演变，相反应特性和力学性能的影响。借助配备有能量色散光谱仪（EDS），X射线衍射（XRD）和电子背散射衍射（EBSD）的扫描电子显微镜（SEM）进行微观结构表征。使用硬度测试检查机械性能。结果表明，通过添加0.2 wt。％的镁，可以成功制备出{100}晶面形状的立方初生Mg ₂ Si晶体，平均粒径为35μm。钡元素相对于铝镁硅熔化。首次表明，Al ₄ Ba化合物可作为初级Mg的核凝固过程中的₂ Si导致大量Mg ₂ Si初级粒度的细化。此外，Al ₂ Si ₂ Ba和AlSiBa金属间化合物（IMCs）的形成对Mg ₂ Si颗粒的细化很容易。因此，合金的硬度从60.21 Hv增加到67.83 Hv。此外，热分析表明，随着Ba的添加，初生Mg ₂ Si相的成核温度升高。钡的添加在确定初生Mg ₂的形状方面起着重要作用可以从粗晶状结构（0重量％）转变为具有八个{111}和四个{100}切面（0.08重量％）的组合的晶体，然后变成截头的立方（0.1重量％）的Si晶体，最后是一个由{100}晶面（0.2 wt。％）完全包围的立方体，并且Ba浓度增加。这项研究表明，立方晶初生Mg ₂ Si的生长过程是由于Ba原子的吸收和中毒作用而导致的，初生Mg ₂ Si的{100}面的生长速率逐渐降低，因此， {100}张脸暴露。此外，在改性合金中，发现了立方初生Mg ₂ Si的骨架型生长过程，其中检测到一些小丘的生长步骤。