Enhanced homogeneity and crack reduction in al alloy: an in-situ approach for optimised powder size in powder bed fusion-laser beam (PBF-LB)

Abstract This study investigates the optimisation of powder size in in-situ alloying during Powder Bed Fusion-Laser Beam (PBF-LB) to enhance elemental homogeneity and minimise defects. A empirical model was developed to establish the relationship between powder size, specific Enthalpy, density, and cohesive force, promoting comparable melting of constituent elements. The model was validated using Al-Ni alloys, where coarse powders significantly improved building stability, increasing the proportion of non-cracked samples from 35.3 to 67.6%. SEM, backscattered imaging, and EDS analysis confirmed a more uniform Ni distribution and reduced non-dissolved Ni content in coarse powders, while EBSD analysis revealed a more uniform grain structure. The findings highlight the critical role of powder size in controlling microstructure evolution, mitigating defects, and improving mechanical reliability in PBF-LB. The proposed model provides a systematic framework for powder selection, supporting the development of defect-free, high-performance alloys for advanced industrial applications.