High-performance 3D-printed alloys for cars and airplanes
Aktuell, Wissenschaft, Industrie, STRESS-SPEC |
Stable alloys despite strong applied forces
So far, studies on the Scalmalloy® alloy have mainly focused on the influence of its composition and crystal structure on the alloy’s stability. However, this information is insufficient for applications in which the alloy must retain its shape under high forces or return to its original shape after an elastic deformation. When an alloy is stretched, microscopic changes occur initially. This behaviour is the so-called microplasticity of the material, where atoms within the material change their position slightly, thus showing a dislocation. Macroscopic deformation, visible to the naked eye, occurs only later. This is known as the macroplasticity of the alloy. “We need a deep understanding of the material properties for a safe and efficient use of the aluminium alloy,” says Dr Xingxing Zhang, who conducted his research in cooperation with representatives from the automotive and aviation industries.
X-rays to examine the samples
Dr. Xingxing Zhang is currently working in Beijing at the Institute of High Energy Physics of the Chinese Academy of Sciences. He performed the measurements at the DESY research facility in Hamburg together with Dr. Weimin Gan, instrument scientist at the Helmholtz Zentrum Hereon at the MLZ. At DESY, X-rays are available to resolve crystal structures and their defects with a high resolution. The scientists compared the 3D printed samples, once untreated and once after direct aging of the sample, and in both cases before and during the application of a tensile load. Although direct aging is an established method, its influence on the alloy’s microplasticity has yet to be fully clarified. They used the special machine developed for the STRESS-SPEC instrument to apply the tensile load.
Defect concentration is key to improving the alloy
The scientists identified distinct deformation stages in the material’s behaviour through continuous tensile loading. They measured both macroscopic and microscopic deformations, as well as their defect concentrations, to gain insights into the underlying mechanisms. Interestingly, the scientists found that the deformation stages exhibited by as-built and direct-aged aluminium alloys differ significantly, with distinct defect concentrations. Dr. Xingxing Zhang developed a novel three-dimensional defect-concentration-based crystal plasticity model to model this complex behaviour, which accurately predicts macroscopic and microscopic properties, including defect concentrations. The defect concentrations play a crucial role in determining the stability of the alloys, and now, scientists understand their evolution better when applying a tensile force. “This is an important step forward”, says Dr. Xinxing Zang.
Using X-ray scattering on the sample, the researchers could calculate the material’s stress. Simulations supported the experimental results. Neutrons, such as those available at the MLZ, on the other hand, could provide information on the positions of the atomic nuclei and supplement the measurements.
Original publication:
X.X. Zhang, P.-P. Bauer, A. Lutz, C. Wielenberg, F. Palm, W.M. Gan, and E. Maawad
Microplasticity and macroplasticity behavior of additively manufactured Al-Mg-Sc-Zr alloys: In-situ experiment and modeling
International Journal of Plasticity 166 (2023) 103659
DOI: 10.1016/j.ijplas.2023.103659
More information:
In addition to the Heinz Maier-Leibnitz Zentrum, researchers from the following institutions were involved in the investigations:
- Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, China
- German Aerospace Center (DLR), Institute of Materials Research, Cologne, Germany
- Mercedes Benz AG, Research and Development Department, Böblingen, Germany
- Premium AEROTEC GmbH, Varel, Germany
- Airbus Central Research & Technology (CRT), Taufkirchen, Germany
- Institute of Materials Physics, Helmholtz-Zentrum Hereon, Geesthacht, Germany