Correlative Synchrotron X-ray Imaging and Diffraction of Directed Energy Deposition Additive Manufacturing
Correlative Synchrotron X-ray Imaging and Diffraction of Directed Energy Deposition Additive Manufacturing
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DOI：
10.1016/j.actamat.2021.116777
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发表时间：
2021-03-13
期刊：
影响因子：
9.4
通讯作者：
Lee, Peter D.
中科院分区：
文献类型：
--
作者：
Chen, Yunhui;Clark, Samuel J.;Lee, Peter D.
通过对镍基高温合金 IN718 进行原位操作同步加速器 X 射线成像和衍射研究，揭示了定向能量沉积增材制造 (DED-AM) 的控制机制行为。使用独特的 DED-AM 工艺复制器，实空间成像可以量化凝固过程中的熔池边界和流动动力学。该成像知识还用于在转变和应力发展过程中以 100 µm 的空间分辨率对时间分辨微结构相进行精确衍射测量。衍射量化的热梯度使得能够预测枝晶凝固微观结构并将其与应力状态耦合。快速冷却速率完全抑制了第二相的形成或固态再结晶。凝固后，应力在冷却过程中迅速增加至屈服强度。这一见解与 IN718 的大凝固范围相结合表明，积累的塑性耗尽了合金的延展性，导致液化裂纹。这项研究揭示了 DED-AM 过程中控制高度非平衡微观结构形成的机制。 ？ 2021 Acta Materialia Inc. 由 Elsevier Ltd 出版。保留所有权利。
The governing mechanistic behaviour of Directed Energy Deposition Additive Manufacturing (DED-AM) is revealed by a combined in situ and operando synchrotron X-ray imaging and diffraction study of a nickel base superalloy, IN718. Using a unique DED-AM process replicator, real-space imaging enables quantification of the melt-pool boundary and flow dynamics during solidification. This imaging knowledge was also used to inform precise diffraction measurements of temporally resolved microstructural phases during transformation and stress development with a spatial resolution of 100 ?m. The diffraction quantified thermal gradient enabled a dendritic solidification microstructure to be predicted and coupled to the stress state. The fast cooling rate entirely suppressed the formation of secondary phases or recrystallisation in the solid-state. Upon solidification, the stresses rapidly increase to the yield strength during cooling. This insight, combined with the large solidification range of IN718 suggests that the accumulated plasticity exhausts the ductility of the alloy, causing liquation cracking. This study has revealed the mechanisms that govern the formation of highly non-equilibrium microstructures during DED-AM. ? 2021 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.