Semi-finished powder of aluminum matrix composite for a direct energy deposition additive manufacturing

Abstract

Abstract. Aluminum-Matrix Composites (AMCs) are particle-reinforced aluminum matrix composites that are well-established in high-performance lightweight components in the automotive and aerospace industries. So far, the use of AMC materials has been limited to components manufactured using casting technology (e.g. brake discs). The adaption of AMC materials in Additive Manufacturing (AM) processes, such as powder feedstock for Direct Energy Deposition (DED), is dependent on the availability of the corresponding semi-finished product. An approach for the production of such a semi-finished product is presented in the current work. This study presents, how powder as semi-finished product for the DED processes, is produced from cast ingots manufactured by Direct-Vacuum-Casting (DVC). The novel DVC process allows a SiCP particle content of up to 35%, whereas conventional AMC casting processes can only achieve a fully embedded SiCP particle content of up to 20%. Particular attention is paid to ensuring that the SiCP particles remain completely embedded in the aluminum matrix after the semi-finished product has been produced. However, there is currently not an extensive literature existing on semi-finished products from AMC materials in AM processes. Therefore, in these investigations, ultrasonic atomization technology was used to produce of AMC powder with an average size of 80 µm as a feedstock material. The microstructure analysis of this powder demonstrated the presence of primary SiCP particles with non-optimal distribution. Nevertheless, the AMC powder was used in the subsequent DED process studies. It was possible to develop the fundamentals for the deposition processing of AMC powder. As demonstrated by microscope techniques, secondary SiCP particles were precipitated in an aluminum matrix with complete embedding during deposition, pointing the way forward to develop AMC powders as semi-finished products in AM processes.