Surface Resistivity Correlation to Nano-defects in Laser Powder Bed Fused Molybdenum (Mo)-Silicon Carbide (SiC) Alloys

The integration of SiC nanoparticles into Laser Powder Bed Fusion (LB-PBF) Mo printing represents a significant advancement in refractory metal additive manufacturing. We examined how varying nanoparticle sizes of SiC at 0.01 mass fraction in Mo affects the microstructure and electrical resistivity of LB-PBF-printed molybdenum samples. Resistivity decreased with reduction of oxygen content in MoOx by SiC at high temperature. At a Linear Energy Densities (LED) of 1.8 J/mm, the addition of 80 nm SiC particles produced a 46% reduction in microporosity, while sheet resistance is decreased by 6% at LED of 2.0 J/mm with 80 nm SiC particles, reflecting reduced nanostructure heterogeneity. Improvements in sample properties stem from several mechanisms: SiC nano-particles serve as oxygen scavengers, accelerate rates of phase transformations, and enhance laser absorption efficiency. The SiC dual role as sacrificial reducing agent and Mo disilicide phase promoter represents a novel approach to reducing microcracking and porosity in LB-PBF-printed Mo components. Influences of particle size on microstructure of products suggests that optimized nanoparticle addition could become a universal strategy for enhancing the LB-PBF processing of refractory metals, particularly for applications requiring enhanced mechanical and electrical performance.