Correlative Synchrotron X-ray Imaging and Diffraction of Directed Energy Deposition Additive Manufacturing
Yunhui Chen, Samuel J. Clark, David M. Collins, Sebastian Marussi, Simon A. Hunt, Danielle M. Fenech, Thomas Connolley, Robert C. Atwood, Oxana V. Magdysyuk, Ga… 展开作者
Yunhui Chen, Samuel J. Clark, David M. Collins, Sebastian Marussi, Simon A. Hunt, Danielle M. Fenech, Thomas Connolley, Robert C. Atwood, Oxana V. Magdysyuk, Gavin J. Baxter, Martyn A. Jones, Chu Lun Alex Leung, Peter D. Lee
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 process replicator, real-space phase-contrast imaging enables quantification of the melt-pool boundary and flow dynamics during solidification. This imaging knowledge informed precise diffraction measurements of temporally resolved microstructural phases during transformation and stress development with a spatial resolution of 100 $μ$m. The diffraction quantified thermal gradient enabled a dendritic solidification microstructure to be predicted and coupled to the stress orientation and magnitude. 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 IN718 $'$s large solidification range suggests that the accumulated plasticity exhausts the alloy$'$s ductility, causing liquation cracking. This study has revealed additional fundamental mechanisms governing the formation of highly non-equilibrium microstructures during DED-AM.
Fast Desktop-Scale Extrusion Additive Manufacturing
显著提高增材制造（AM）技术的生产率对于其成本效益和与传统加工路线的竞争力至关重要。此外，更快的AM流程与AM的几何多功能性相结合，将为产品设计和定制提供全新的工作流程。我们提出了一个桌面规模的挤出AM系统，实现更大的构建速率比基准的商业系统的设计和验证。这个系统，我们称之为FastFFF，是由我们最近分析的速率限制机制，以传统的熔丝制造（FFF）技术的动机。FastFFF系统相互克服了这些限制，使用坚果进料挤出机，激光加热聚合物增稠器和伺服驱动平行龙门系统，分别实现高挤出力，快速灯丝加热和快速龙门运动。挤压和加热机制包含在一个紧凑的打印头，接收螺纹灯丝和增强传导热传递与光纤耦合二极管激光器。原型系统实现了127 cm 3/hr的体积构建速率，这是在可比分辨率下比商用桌面FFF系统大7倍;打印头的最大挤出速率是约14倍（282 cm 3/hr）。打印头和运动系统的性能限制的特点，和构建速率和分辨率之间的权衡进行评估和讨论。FastFFF技术实现的高速运动和高沉积速率的结合也为刀具路径优化和实时沉积控制带来了挑战和机遇。高速桌面打印提高了AM的新用例和商业模式的可能性，其中手持部件在几分钟而不是几小时内构建。
Data driven analysis of thermal simulations, microstructure and mechanical properties of Inconel 718 thin walls deposited by metal additive manufacturing
Additive manufacturing of Ni-Mn-Sn shape memory Heusler alloy -- Microstructure and magnetic properties from powder to printed parts
Technical University of Darmstadt（达姆施塔特工业大学）；University of Kassel（卡塞尔大学）；Fraunhofer Institution for Material Cycles and Resource Strategies IWKS（弗劳恩霍夫材料循环与资源策略研究所 IWKS）；TU Bergakademie Freiberg（弗莱贝格矿业技术大学）
