The alloy Mo-9Si-8B (at.%) exhibits an acceptable balance between creep and oxidation resistance at high temperatures as well as fracture toughness at ambient temperatures. Since it has a melting point of about 2000 °C, it is a promising ultra-high temperature material for turbine engines. [1] Mo-9Si-8B (at.%) is difficult to process by traditional manufacturing methods due to its brittleness at low temperatures.  Additive manufacturing (AM), however, enables the production of complex near-net-shape bulk materials (e.g., turbine blades) in a single step. Electron Beam Powder Bed Fusion (PBF-EB), which is characterized by extremely high local processing temperatures and associated high powder bed temperatures (i.e.., above the brittle to ductile transition temperature of the material), is well-suited for producing refractory materials with complex geometries. [2]
In this work, the processing window of Mo-9Si-8B (at.%) was rapidly developed using novel strategies that combine high-throughput thermal modelling to predict the melt pool dimensions with in-situ Electron-optical imaging (ELO) for the first time (see Figure 1). High-density bulk Mo-9Si-8B (at.%) samples were successfully fabricated according to the established processing window, and the typical microstructure of the as-built samples was analyzed. This novel approach significantly reduced the effort required to generate processing windows, making it highly viable for developing stable processing conditions for new materials in PBF-EB.