ABSTRACT This paper reports on the characterisation of rapidly solidified Al-4.5 wt% Cu-xSc (x = 0.1, 0.2 or 0.4 wt %). The effect of micro-additions of Sc (up to 0.4 wt %) was examined through microstructural analysis of rapidly solidified, as well as aged samples, by means of electron microscopy, x-ray and neutron diffraction and microhardness measurements. The effect of micro-additions of Sc on the scale of the rapid solidified microstructure was negligible. The Sc additions were supersaturated mainly in the interdendritic regions. However, upon aging of the samples, directly after rapid solidification, nano-precipitates rich in Sc were observed in the matrix and some Sc was also associated with the θ phase. No W-phase was observed in either as atomised or aged samples. Furthermore, dramatic improvements in mechanical properties (specifically hardness) were achieved. This work highlights the use of various and complementary tools to characterise the effect of micro-additions of Sc to hypoeutectic Al-Cu alloys over a wide range of solidification thermal histories. It also demonstrates the capability of designing alloys and process strategies with unique microstructures and mechanical properties superior to age hardened Al-4.5 wt% Cu alloys.

中文翻译：

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钪对快速凝固亚共晶铝铜的影响

摘要 本文报告了快速凝固的 Al-4.5 wt% Cu-xSc (x = 0.1、0.2 或 0.4 wt%) 的表征。通过电子显微镜、X 射线和中子衍射以及显微硬度测量对快速凝固和老化样品的微观结构分析，研究了微量添加 Sc（高达 0.4 wt%）的影响。微量添加 Sc 对快速凝固显微组织尺度的影响可以忽略不计。Sc 添加物主要在枝晶间区域过饱和。然而，在样品老化后，直接在快速凝固后，在基体中观察到富含 Sc 的纳米沉淀物，并且一些 Sc 也与 θ 相相关。在雾化或老化样品中均未观察到 W 相。此外，实现了机械性能（特别是硬度）的显着改善。这项工作强调了使用各种互补工具来表征在广泛的凝固热历史范围内向亚共晶 Al-Cu 合金微量添加 Sc 的影响。它还展示了设计合金和工艺策略的能力，其具有优于时效硬化的 Al-4.5 wt% Cu 合金的独特微观结构和机械性能。