Abstract Al-based monotectic alloys show an interesting combination of wear resistance and mechanical strength. While self-lubricating bismuth (Bi) guarantees an adequate wear resistance, the modification with copper (Cu) can increase the ability to support load. Tailoring the micromorphology of the α-Al phase as well as the distribution of the inclusions of Bi embedded in the α-Al matrix is of prime importance in order to improve the properties. In this paper, various solidification experiments are performed with the Al-3.2wt.%Bi-3wt.%Cu monotectic alloy. Real-time radiographs could be acquired during solidification by using the laboratory device SFINX (Solidification Furnace with IN situ X-radiography). The processing conditions could be chosen in such a way that both cellular and dendritic morphologies of the α-Al phase could be clearly seen in a single test. Micromorphological transitions from dendrites to cells are recognized for samples solidified from different cooling rates, i.e. 0.025 K/s and 0.01 K/s. Measurements of the α-Al dendrite velocity and growth parameters of the Bi droplets during solidification have also been extensively performed. A comprehensive model for the cellular-to-dendritic (CDT) transition of Al-based monotectic alloys is outlined. The model considers the interaction between α-Al and Bi droplets during solidification and its impact on the microstructure.

中文翻译：

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用原位 X 射线照相分析 Al-Bi-Cu 偏晶合金中 α-Al 和 Bi 的复合生长

摘要 铝基偏晶合金显示出耐磨性和机械强度的有趣组合。虽然自润滑铋 (Bi) 保证了足够的耐磨性，但使用铜 (Cu) 进行改性可以增加支撑负载的能力。调整 α-Al 相的微观形貌以及嵌入在 α-Al 基体中的 Bi 夹杂物的分布对于提高性能至关重要。在本文中，对 Al-3.2wt.%Bi-3wt.%Cu 偏晶合金进行了各种凝固实验。通过使用实验室设备 SFINX（具有原位 X 射线照相的凝固炉），可以在凝固过程中获取实时射线照片。可以以这样的方式选择加工条件，使得在一次测试中可以清楚地看到 α-Al 相的细胞和树枝状形态。对于从不同冷却速率（即 0.025 K/s 和 0.01 K/s）固化的样品，可以识别从树突到细胞的微观形态转变。凝固过程中 α-Al 枝晶速度和 Bi 液滴生长参数的测量也已广泛进行。概述了铝基偏晶合金的细胞到枝晶 (CDT) 转变的综合模型。该模型考虑了凝固过程中 α-Al 和 Bi 液滴之间的相互作用及其对微观结构的影响。凝固过程中 α-Al 枝晶速度和 Bi 液滴生长参数的测量也已广泛进行。概述了铝基偏晶合金的细胞到枝晶 (CDT) 转变的综合模型。该模型考虑了凝固过程中 α-Al 和 Bi 液滴之间的相互作用及其对微观结构的影响。凝固过程中 α-Al 枝晶速度和 Bi 液滴生长参数的测量也已广泛进行。概述了铝基偏晶合金的细胞到枝晶 (CDT) 转变的综合模型。该模型考虑了凝固过程中 α-Al 和 Bi 液滴之间的相互作用及其对微观结构的影响。