Oxygen gain and aluminum loss during laser metal deposition of intermetallic TiAl

For manufacturing turbine parts for the aeronautical industry, lightweight structural materials like titanium aluminides are used. One well known example is the alloy Ti-43.5Al-4Nb-1Mo-0.1B (atomic percent) with the commercial name TNMTM. In previous studies, experiments on laser metal deposition of TiAl were performed to evaluate the potential of the technology to repair defective, damaged, or worn blades. Process conditions including post process heat treatment were successfully adjusted. However, oxygen pick-up is still a crucial aspect in laser based additive manufacturing of Ti- and TiAl-based alloys. In this work, approaches were made to analyze the oxygen pick-up as a function of processing parameters and the powder particle size. The results show that the build rate and the powder particle size affect the oxygen content in the consolidated material.