Swiss Federal Laboratories for Materials Science and Technology
Fabrication of novel alloys and (nano-)composites by laser-based additive manufacturing
In recent years, additive manufacturing (AM) of metals has evolved from a mere prototyping technology to a real production technology. Laser powder bed fusion (LPBF) and directed energy deposition (DED) have enabled the layer by layer building of parts with intricate 3D geometries and new functionalities from metal powders. The performance of these parts is determined by the alloy properties which are governed by the complex interrelationships between the alloy composition, the processing parameters, and the resulting microstructure.
Laser beam-based AM processed parts inherent complex thermal histories including rapid solidification of small material volumes with solidification rates exceeding 106 K s-1, followed by multiple heating and cooling cycles with the deposition of subsequent powder layers. This may lead to complex out-of-equilibrium microstructures, pronounced element segregation and crack formation in the bulk alloy. At the same time, these conditions can be exploited for the manufacture of parts from alloys containing meta-stable phases or nano-sized reinforcement particles which are difficult or impossible to fabricate in conventional manufacturing processes.
However, in order to exploit the advantages of additive manufacturing for the fabrication of novel materials, a thorough understanding of the complex interrelationships between the alloy composition, the processing parameters, and the resulting microstructure is required. Based on a combination of computational materials engineering and sophisticated ex situ and in situ experiments, we have successfully developed and fabricated e.g. TiAl and Ni alloys containing nano-sized oxide dispersoids, novel precipitation hardening Al alloys with high strength and ductility, or high nitrogen steels with locally varying para- and ferromagnetic properties using laser powder bed fusion or laser metal deposition. This presentation will give an overview of our activities in this field and show how the special consolidation conditions during AM can be exploited for processing these otherwise difficult-to-process materials.
Christian Leinenbach received his M.Sc. in Materials Science and Engineering from the University of Saarbrücken (DE) in 2000 and his PhD from the University of Kaiserslautern (DE) in 2004. He has been working at Empa since 2005, currently in the position as Head of the Alloy Design for Advanced Processing Technologies (ADAPT) Group in the Laboratory for Advanced Materials Processing in Dubendorf and Thun, Switzerland. In addition, he is adjunct lecturer for materials processing at EPFL, Lausanne, Switzerland.
Dr. Leinenbach’s research work has been focusing on the simulation-assisted development/optimization and microstructure design of structural alloys and metal-matrix composites, mainly for beam-based additive manufacturing and joining applications. Besides, he is interested in the characterization of the influence of advanced processing technologies on the microstructure and properties of complex structural materials.
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