The Optimization of Process and Microstructure of Mo-Re Alloy Fabricated by Laser-Powder Bed Fusion

The additive manufacturing of refractory Mo-Re alloys by laser powder bed fusion (L-PBF) remains largely unexplored due to challenges such as uncontrolled porosity and cracking. This study presents a systematic investigation into the L-PBF processability of a Mo-14Re (wt.%) alloy, and establishes a clear processing window and elucidates the pore formation mechanisms. Using high-quality spherical powder, we fabricated samples across a range of volumetric energy densities (VED). Our results demonstrate a non-linear relationship between VED and relative density, identifying a previously unreported optimal VED window of 208-250 J/mm³ that yields high bulk density. A significant finding is that identical VED values from different power–speed combinations result in distinct microstructures and defect populations. Microstructural analysis revealed fine, equiaxed grains with minimal texture, contrasting with the coarse structures typical of conventional processing. This work provides a fundamental insight into the melt pool dynamics and solidification behavior of Mo-Re alloys in L-PBF.