Laser powder bed fusion of refractory complex concentrated alloys for space propulsion components

Within the EU project ATLAS – “Advanced Design of High Entropy Alloys Based Materials for Space Propulsion” – refractory-based materials for ultra-high temperature applications as well as their additive manufacturing (AM) strategies into complex components for space propulsion systems are being developed. The performance of space propulsion systems is often limited by material properties such as high-temperature strength, resistance to thermal shock as well as corrosion and oxidation resistance. In order to develop new high-temperature materials for AM, various new alloy compositions starting with the design space TaNbTixWy and extended to seven-component systems that were designed by QuesTek Europe AB using an integrated computational materials engineering (ICME) approach have been produced by arc-melting and investigated. The surfaces of arc-melted samples were remolten using a laser applying different parameters and characterized after solidification to establish a preliminary suitability for laser powder bed fusion (LPBF) processing. The results of the investigation, in particular the amount and type of cracks within the solidified melt pool regions are correlated with the deformation behaviour during in situ high energy synchrotron X-ray diffraction during compression testing. Finally, the investigations are verified with LPBF experiments carried out with pre-alloyed powder of a seven-component refractory complex concentrated alloy system. Simultaneously to the efforts in alloy development and material processing, the DLR pursues the investigation of a building approach for small space thrusters. The activities are closely linked to DLR’s research on build strategies, manufacturing and testing of complex space propulsion systems from small thrusters up to mid-sized rocket engine liners or shrouded impellers for turbo pumps