Eutectic Al alloys with tailored solidification path to probe fundamental aspects of solidification in laser-based AM II

具有定制凝固路径的共晶铝合金，用于探测基于激光的 AM II 凝固的基本方面

• 批准号: 409726740
• 负责人: Dr. Markus Apel
• 金额: --
• 依托单位: Access e.V.
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/409726740?language=en
• 关键词: Eutectic; Al; alloys; tailored; solidification

Our project goal is to evaluate the Al-Ni-Ce system around its zone of coupled eutectic growth for its suitability for PBF-LB/M. In particular, ultra-fine eutectic structures with superior mechanical properties are originally targeted. In phase 1, we have already verified two of our research hypotheses, namely that in Al-Ni the material microstructures, in particular an ultra-fine binary eutectic, can be designed by selecting hypereutectic alloy compositions and specific processing conditions. Indeed, while the spacing has proven efficient to apprehend the solidification velocity in the case of a eutectic coupled growth, a broad range of other microstructures have been evidenced, both experimentally and numerically (phase-field method), illustrating the strong asymmetric coupled zone of eutectic growth. Moreover, the process and material parameters also influence the melt pool dynamics, and a link between its dimensions and the porosity formation via keyholing has been established. In phase 2 of SPP2122, this link will be investigated in more detail. Especially, the influence of the hatch distance and the laser spot size will receive our attention in order to better understand the keyholing onset dependent on alloy composition and thereby broaden the process window, particularly at low laser scanning speed. Melt pool simulations, as well as experiments with the ternary Al-Ni-Ce alloy, will be performed. Reducing porosity goes hand in hand with generating appropriate microstructures. In this respect, the variety of possible microstructures is expected to become even broader in the ternary alloy system than for binary alloys. A particular focus will be put on the three-phase eutectic coupled growth in order to produce ultra-fine ternary eutectics as well as on a two-phase nanocrystalline structure, evidenced during phase 1 for large scanning speeds, with grain sizes in the range of 50 nm for both phases. This nanocrystalline structure emerges intrinsically, shows remarkably large hardness values and no solidification cracks, however, it seems to be prone to cold cracks.We will systematically perform mechanical testing (hardness, tensile tests) on the produced samples when porosity is low and the microstructure is promising. Our project should then provide, at the end of phase 2, a procedure to build dense specimens with, possibly even locally, optimized properties.

我们的项目目标是评估Al-Ni-Ce系统在其耦合共晶生长区域周围是否适合PBF-LB/M。特别地，具有上级机械性能的超细共晶结构最初是目标。在第一阶段，我们已经验证了我们的两个研究假设，即在Al-Ni材料的微观结构，特别是超细二元共晶，可以通过选择过共晶合金成分和特定的工艺条件进行设计。事实上，虽然间距已被证明是有效的理解凝固速度的情况下，共晶耦合生长，广泛的其他微观结构已被证明，实验和数值（相场法），说明强不对称耦合区的共晶生长。此外，工艺和材料参数也影响熔池动力学，其尺寸和孔隙形成之间的联系，通过锁眼已经建立。在SPP 2122的第2阶段，将更详细地研究此链路。特别是，舱口距离和激光光斑尺寸的影响将得到我们的注意，以更好地了解依赖于合金成分的小孔发病，从而扩大工艺窗口，特别是在低激光扫描速度。将进行熔池模拟以及三元Al-Ni-Ce合金的实验。减少孔隙率与生成适当的微观结构密切相关。在这方面，各种可能的微观结构，预计将成为更广泛的三元合金系统比二元合金。一个特别的重点将放在三相共晶耦合生长，以产生超细三元共晶以及两相纳米晶结构，证明在阶段1的大扫描速度，与晶粒尺寸在50 nm的范围内为两个阶段。这种纳米晶结构是固有的，显示出非常大的硬度值，没有凝固裂纹，但似乎很容易出现冷裂纹。当孔隙率低且显微组织有希望时，我们将对生产的样品进行系统的机械测试（硬度，拉伸测试）。然后，我们的项目应该提供，在第二阶段结束时，一个程序，建立密集的标本，甚至可能是局部优化的属性。