Microalloying can potentially enhance the uniformity of the microstructure and mechanical properties of AlMgSc alloys. In this study, wire-arc directed-energy deposition (WA-DED) was performed to prepare AlMgScZr and AlMgScTi alloy deposits with self-developed wires, followed by a comparative analysis of their microstructure and mechanical properties to investigate the effects of two microalloying elements, Zr and Ti. The microstructure of the AlMgScZr and AlMgScTi alloy deposits were analysed using optical microscopy, scanning electron microscopy, electron backscatter diffraction, and transmission electron microscopy. The mechanical properties of the deposits were tested and the burning tendencies of Zr and Ti were evaluated. The AlMgScZr alloy exhibited a significant number of columnar grains, whereas the AlMgScTi alloy exhibited the microstructure predominantly composed of fine equiaxed grains. No Al₃(Sc, Zr) phase was observed in the AlMgScZr alloy, while Al₃(Sc, Ti) phase was identified in the AlMgScTi alloy. The AlMgScTi alloy exhibited superior hardness and tensile properties compared with the AlMgScZr alloy. The substantial burning of Zr and minimal burning of Ti contributed to the differences in the microstructure and mechanical properties between the AlMgScZr and AlMgScTi alloys. This study provides novel insights into the selection of microalloying elements for AlMgSc alloys fabricated via WA-DED.

中文翻译：

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线弧定向能量沉积制备的 Ti 和 Zr 微合金化 AlMgSc 合金沉积的显微组织和力学性能的比较研究

微合金化可以潜在地提高 AlMgSc 合金的微观组织和机械性能的均匀性。在本研究中，采用线弧定向能量沉积 （WA-DED） 技术，用自主开发的线材制备 AlMgScZr 和 AlMgScTi 合金沉积物，然后对它们的微观结构和力学性能进行比较分析，以研究 Zr 和 Ti 两种微合金元素的影响。使用光学显微镜、扫描电子显微镜、电子背散射衍射和透射电子显微镜分析了 AlMgScZr 和 AlMgScTi 合金沉积物的微观结构。测试了沉积物的机械性能，并评估了 Zr 和 Ti 的燃烧趋势。AlMgScZr 合金表现出大量的柱状晶粒，而 AlMgScTi 合金表现出主要由细等轴晶粒组成的微观组织。在 AlMgScZr 合金中未观察到 Al ₃ （Sc， Zr） 相，而在 AlMgScTi 合金中观察到 Al ₃ （Sc， Ti） 相。与 AlMgScZr 合金相比，AlMgScTi 合金表现出优异的硬度和拉伸性能。Zr 的大量燃烧和 Ti 的轻微燃烧导致了 AlMgScZr 和 AlMgScTi 合金之间微观组织和机械性能的差异。本研究为通过 WA-DED 制备的 AlMgSc 合金的微合金元素的选择提供了新的见解。