Abstract The paper presents detailed analyses of solidification experiments performed on a refined Al-20 wt.%Cu alloy using the SFINX (Solidification Furnace with IN situ X-radiography) laboratory facility. Directional solidifications of a sheet-like sample were carried out in a horizontal configuration, with the main surface of the sample parallel to the ground. The sample was solidified for a wide range of cooling rates to obtain various grain structures, from columnar to elongated and equiaxed. The formation of the grain structure was observed in-situ and in real-time by X-radiography, which allows the dynamic of solidification phenomena to be thoroughly analyzed. Based on the radiographs, quantitative measurements were performed to accurately describe the solidified grain structure, namely the nucleation position, nucleation rate, grain size, grain elongation factor and growth orientation. The experiments showed that increasing the growth velocity leads to a decrease of both the grain size and grain elongation factor, resulting in a more homogeneous and isotropic grain distribution. The grain characteristic parameters were also sensitive to variations of the temperature gradient in the Field-of-View. The results were discussed by analyzing the impact of the solidification parameters on the constitutionally undercooled liquid zone ahead of the solidification front.

中文翻译：

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生长速度对精制 Al-20wt.%Cu 合金定向凝固过程中晶粒结构形成的影响

摘要 本文详细分析了使用 SFINX（具有原位 X 射线照相术的凝固炉）实验室设施对精制 Al-20 wt.% Cu 合金进行的凝固实验。片状样品的定向凝固在水平配置中进行，样品的主表面平行于地面。样品在很宽的冷却速率范围内凝固，以获得从柱状到细长和等轴的各种晶粒结构。通过 X 射线照相术原位实时观察晶粒结构的形成，从而可以彻底分析凝固现象的动态。根据射线照片，进行定量测量以准确描述凝固的晶粒结构，即形核位置、形核速率、晶粒尺寸、晶粒伸长因子和生长方向。实验表明，增加生长速度会导致晶粒尺寸和晶粒伸长因子的降低，从而导致更均匀和各向同性的晶粒分布。晶粒特征参数也对视场中的温度梯度变化敏感。通过分析凝固参数对凝固前沿之前的结构过冷液体区的影响来讨论结果。晶粒特征参数也对视场中的温度梯度变化敏感。通过分析凝固参数对凝固前沿之前的结构过冷液体区的影响来讨论结果。晶粒特征参数也对视场中的温度梯度变化敏感。通过分析凝固参数对凝固前沿之前的结构过冷液体区的影响来讨论结果。