The present study investigates the laser powder bed fusion of Al 2024 alloy. The Al 2024 is one of the most widely used aluminium alloys in aerospace industries owing to its excellent mechanical properties such as high strength-to-weight ratio, high fatigue and fracture strength, etc. However, the additive manufacturing of the Al 2024 alloy is scarce in literature due to its high solidification cracking and low processing window. The current study explores the composition changes tailored for the additive process to promote columnar to equiaxed transformation, constitutional supercooling and heterogeneous nucleation. The Al 2024 alloy was modified using Ti to eliminate solidification cracking. The mechanical characteristics such as tensile, hardness, and fracture toughness were evaluated for varying orientations in as-fabricated and T6 samples, and the corresponding strengthening mechanisms were explored in detail using the microstructural features. The maximum tensile strength obtained in the T6 condition (483 MPa) was comparable to the wrought Al 2024 and the maximum hardness and fracture toughness were better compared to the wrought counterparts. The different precipitates, such as AlCu/AlCuMg, evolved during T6 heat treatment, along with the ultrafine grains produced due to Ti addition, were observed to be the primary strengthening mechanism contributing to the high strength of the additive samples.

中文翻译：

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Ti 改性 Al 2024 合金上的激光粉末床熔合：构建方向和 T6 处理对机械行为、微观结构特征和强化机制的影响

本研究研究了 Al 2024 合金的激光粉末床熔化。Al 2024 具有高强度重量比、高疲劳强度和断裂强度等优异的力学性能，是航空航天工业中应用最广泛的铝合金之一。然而，Al 2024 合金的增材制造技术还存在一些问题。由于其高凝固裂纹和低加工窗口，文献中很少见。目前的研究探索了为增材工艺量身定制的成分变化，以促进柱状到等轴转变、组织过冷和异质成核。使用 Ti 对 Al 2024 合金进行改性以消除凝固裂纹。针对不同取向的制造样品和 T6 样品的拉伸、硬度和断裂韧性等机械特性进行了评估，并利用微观结构特征详细探索了相应的强化机制。T6 条件下获得的最大拉伸强度 (483 MPa) 与锻制 Al 2024 相当，最大硬度和断裂韧性优于锻制 Al 2024。T6 热处理过程中形成的不同析出物（例如 AlCu/AlCuMg）以及由于添加 Ti 而产生的超细晶粒，被认为是有助于添加剂样品高强度的主要强化机制。