Van Cauwenbergh P, Samaee V, Thijs L, Nejezchlebová J, Sedlák P, Iveković A, Schryvers D, Van Hooreweder B, Vanmeensel K
3D Systems Leuven, Grauwmeer 14, 3001, Leuven, Belgium.
Department of Physics, Electron Microscopy for Materials Science (EMAT), University of Antwerp, Groenenborgerlaan 171, 2020, Antwerp, Belgium.
Sci Rep. 2021 Mar 19;11(1):6423. doi: 10.1038/s41598-021-85047-2.
Tailoring heat treatments for Laser Powder Bed Fusion (LPBF) processed materials is critical to ensure superior and repeatable material properties for high-end applications. This tailoring requires in-depth understanding of the LPBF-processed material. Therefore, the current study aims at unravelling the threefold interrelationship between the process (LPBF and heat treatment), the microstructure at different scales (macro-, meso-, micro-, and nano-scale), and the macroscopic material properties of AlSi10Mg. A similar solidification trajectory applies at different length scales when comparing the solidification of AlSi10Mg, ranging from mould-casting to rapid solidification (LPBF). The similarity in solidification trajectories triggers the reason why the Brody-Flemings cellular microsegregation solidification model could predict the cellular morphology of the LPBF as-printed microstructure. Where rapid solidification occurs at a much finer scale, the LPBF microstructure exhibits a significant grain refinement and a high degree of silicon (Si) supersaturation. This study has identified the grain refinement and Si supersaturation as critical assets of the as-printed microstructure, playing a vital role in achieving superior mechanical and thermal properties during heat treatment. Next, an electrical conductivity model could accurately predict the Si solute concentration in LPBF-processed and heat-treated AlSi10Mg and allows understanding the microstructural evolution during heat treatment. The LPBF-processed and heat-treated AlSi10Mg conditions (as-built (AB), direct-aged (DA), stress-relieved (SR), preheated (PH)) show an interesting range of superior mechanical properties (tensile strength: 300-450 MPa, elongation: 4-13%) compared to the mould-cast T6 reference condition.
为激光粉末床熔融（LPBF）加工的材料定制热处理对于确保高端应用中优异且可重复的材料性能至关重要。这种定制需要深入了解LPBF加工的材料。因此，当前的研究旨在揭示工艺（LPBF和热处理）、不同尺度（宏观、介观、微观和纳米尺度）的微观结构以及AlSi10Mg的宏观材料性能之间的三重相互关系。在比较AlSi10Mg从铸模铸造到快速凝固（LPBF）的凝固过程时，类似的凝固轨迹适用于不同的长度尺度。凝固轨迹的相似性引发了为什么布罗迪 - 弗莱明斯胞状微观偏析凝固模型能够预测LPBF打印态微观结构的胞状形态的原因。在更精细的尺度上发生快速凝固时，LPBF微观结构表现出显著的晶粒细化和高度的硅（Si）过饱和。本研究已确定晶粒细化和Si过饱和是打印态微观结构的关键特性，在热处理过程中实现优异的机械和热性能方面发挥着至关重要的作用。接下来，一个电导率模型可以准确预测LPBF加工和热处理后的AlSi10Mg中的Si溶质浓度，并有助于理解热处理过程中的微观结构演变。与铸模T6参考状态相比，LPBF加工和热处理后的AlSi10Mg状态（铸态（AB）、直接时效（DA）、去应力（SR）、预热（PH））显示出一系列有趣的优异机械性能（抗拉强度：300 - 450MPa，伸长率：4 - 13%）。
