High-throughput Alloy Development for Additive Manufacturing via 3D-Extreme High-speed Laser Material Deposition (3D-EHLA)

• Subject Area: Synthesis and Properties of Functional Materials ; Mechanical Properties of Metallic Materials and their Microstructural Origins
• Term: since 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 434555091

Additive Manufacturing (AM) technologies are a key enabler of individualized and resource-efficient production of highly functional parts. Today, AM technologies cannot reach their full potential due to the lack of high-performance materials for AM which exploit the process-inherent conditions such as extremely high heating and cooling rates. Thus, novel high-throughput approaches have to be designed to allow an agile and efficient way of developing new AM-suited materials. Processes with the possibility of in-situ mixing multiple materials/elements such as Laser Material Deposition (LMD) and its variant Extreme High-speed Laser Material Deposition (EHLA) are extremely suitable for the resource-efficient and automatable testing of numerous alloys. EHLA's innovation (Patent FhG/RWTH Aachen, 2015) lies in the fact that the powder particles are not molten in the melt pool on the substrate, as in conventional Laser Material Deposition (LMD), but above it (fig. 1). This enables layers with thicknesses from 10-300µm at process speeds of up to 200m/min. Due to these characteristics, the cooling rates during solidification can be varied to high degree in the regime of approx. 10^2-10^4K/s (conventional LMD) and approx. 10^4 and 10^6K/s (EHLA) by different process speeds along with tailored intensity, laser power and system technology. Hence, material design aspects, e.g. segregations can be specifically adjusted to influence failure mechanisms (e.g. TWIP, TRIP). So far, the application of EHLA is limited to rotationally symmetrical samples due to the high surface speeds. Yet, recent developments at Fraunhofer ILT shows that EHLA is also applicable in a non-rotational setup. With such a setup critical areas, e.g. reversal points (increased heat input and change of the cooling/solidification conditions) can be investigated, too. This combination - high speed and full 3D-capability - allows the applied-for 3D-EHLA machine also to emulate other AM technologies (e.g. Laser-Powder Bed Fusion). The machine will be able to process up to 8 (elementary) powder materials synchronously with process speed up to 200m/min at 5g acceleration. To control melt formation and solidification by applying different temperature profiles (by means of tailored intensities) different optics can be integrated into the processing head. Furthermore, numerous devices for material characterization and process observation (e.g. high-speed camera, ratio pyrometer, laser-induced breakdown-spectroscopy, etc.) will be part of the setup to enable instant feedback of the process conditions. Thus, this one-of-a-kind machine covers not only the high throughput material development for LMD but offers the opportunity to emulate various AM processes (by the control of the local cooling conditions from 10^2-10^6K/s together with adapted process strategies). Together with the in-situ material mixing capability of LMD/EHLA this enables a whole new step for the material development in AM (fig. 1).

• DFG Programme: Major Instrumentation Initiatives
• Major Instrumentation: LMD-Anlage
• Instrumentation Group: 2110 Formen-, Modellherstellung und gießereitechnische Maschinen
• Applicant Institution: Rheinisch-Westfälische Technische Hochschule Aachen
• Leader: Professor Dr.-Ing. Johannes Henrich Schleifenbaum
• Co-Investigators: Professor Dr.-Ing. Christoph Broeckmann; Professor Dr.-Ing. Andreas Bührig-Polaczek; Professor Dr.-Ing. Christian Haase; Professor Dr.-Ing. Ulrich Krupp; Professor Dr. Peter Loosen; Professor Jochen M. Schneider, Ph.D.