Gao Lin, Chen Yan, Zhang Xuan, Agnew Sean R, Chuang Andrew C, Sun Tao
Department of Materials Science and Engineering, University of Virginia, Charlottesville, VA, USA.
Nuclear Science and Engineering Division, Argonne National Laboratory, Lemont, IL, USA.
Nat Commun. 2025 May 20;16(1):4696. doi: 10.1038/s41467-025-59988-5.
Materials processed by fusion-based additive manufacturing (AM) typically exhibit relatively high dislocation densities, along with cellular structures and elemental segregation. This representative structural feature significantly influences material performance; however, post-mortem microstructure characterizations of AM materials cannot capture the dynamic evolution of dislocations during the manufacturing process, thereby offering limited mechanism-based guidance for further advancing AM techniques and facilitating the qualification and certification of AM products. In this study, we conduct operando high-energy synchrotron X-ray diffraction experiments on wire-laser directed energy deposition of 316 L stainless steel. Through a unique configuration, our operando synchrotron experiments semi-quantitatively probe the dislocation density in solid phases and their dynamic changes during solidification and subsequent cooling. By integrating this advanced synchrotron technique with multi-physics simulation, in-situ neutron diffraction, and multi-scale electron microscopy characterization, our mechanistic study aims to elucidate the effects of rapid cooling and subsequent thermal cycling on the dislocation generation and evolution.
通过基于熔合的增材制造（AM）加工的材料通常表现出相对较高的位错密度，以及胞状组织和元素偏析。这种典型的结构特征显著影响材料性能；然而，AM材料的事后微观结构表征无法捕捉制造过程中位错的动态演变，从而为进一步推进AM技术以及促进AM产品的鉴定和认证提供基于机制的指导有限。在本研究中，我们对316L不锈钢的激光定向能量沉积进行了原位高能同步加速器X射线衍射实验。通过独特的配置，我们的原位同步加速器实验半定量地探测了凝固和随后冷却过程中固相中 的位错密度及其动态变化。通过将这种先进的同步加速器技术与多物理场模拟、原位中子衍射和多尺度电子显微镜表征相结合，我们的机理研究旨在阐明快速冷却和随后的热循环对位错产生和演变的影响。
