Reactive Synthesis in Additive Manufacturing of an Ultrahigh Temperature MoSiB Alloy

To address the challenges of processing ultrahigh-temperature refractory metal alloys, a novel reactive synthesis-based additive manufacturing technique has been developed to fabricate chemically uniform and dense alloys. The present study demonstrates the reactive additive manufacturing of Mo-4Si-6B (at.%), a high-temperature refractory alloy, using directed energy deposition. For the alloy in the Mo-Si-B system, a premixed blend of molybdenum, silicon nitride, and boron nitride powder was used to make an alloy with the desired composition. A dimensionless number was used to design the process parameters and build efficiency. High-throughput synthesis using build height measurements of individual samples validated the predicted process parameters. Microstructural characterization investigations and indentation hardness testing indicated chemically uniform samples with refined microsegregation in samples with high hardness and no cracking, even with a 10-kg force load. The results demonstrate an effective strategy for additively manufacturing refractory alloys.