The twin-roller casting process is a novel technology used to produce aluminium and other alloys. In this study, the Al-Fe-Si alloy was twin-roller cast into a billet with a thickness of 7.0 mm. This was followed by an annealing process at 480°C for 16 hours. Abnormal grains of more than 15 mm in the nominal diameter were found to have formed on the surface of the billet. Scanning electronic microscopy observation, energy diffraction spectrum, microarea X-ray diffraction, and electronic backscattered diffraction analysis were performed to study this abnormal grain growth. The results showed that abnormal grain nucleates in the region of (100) <001> texture formed in the twin-roller casting process. The growth of abnormal grain was governed by the coalescence of the abnormal grain with its surrounding normal grains, with an average orientation angle of 47° between both the types of grains. High-strain-concentrated regions on the surface layer of the billet were induced by the heterogeneously distributed Fe particles formed in the twin-roller casting process. The presence of these regions accelerates the abnormal grain growth in the following annealing process of the billet.

中文翻译：

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双辊铸铝铁硅合金退火过程中晶粒长大的异常机理

双辊铸造工艺是一种用于生产铝和其他合金的新颖技术。在这项研究中，Al-Fe-Si合金是双辊铸造成厚度为7.0 mm的钢坯。随后在480℃下退火16小时。发现在坯料表面上形成了公称直径大于15mm的异常晶粒。进行了扫描电子显微镜观察，能量衍射谱，微区X射线衍射和电子反向散射衍射分析，以研究这种异常晶粒的生长。结果显示在双辊铸造过程中形成的（100）<001>织构区域中异常晶粒成核。异常晶粒的生长取决于异常晶粒与周围正常晶粒的结合，两种晶粒之间的平均取向角为47°。通过在双辊铸造过程中形成的异质分布的铁颗粒，在坯料表面层上产生了高应变集中区域。这些区域的存在会在随后的钢坯退火过程中加速晶粒的异常生长。