Effect and mechanism of powder morphology on mechanical properties of nickel‑based metal matrix composites TiC‑IN738LC in laser powder bed fusion

The fabrication of high-performance nickel-based metal matrix composites through laser powder bed fusion (L-PBF) represents a dominant area of research. This study introduces Titanium Carbide (TiC) nanoparticles and prepares the TiC-IN738LC composites using mechanical and wet chemical mixing methods. The morphology and sphericity of the powders produced by these methods were analyzed and observed that powders processed chemically retained superior morphology and characteristics over ball-milled, such as enhanced sphericity and uniform nanoparticle distribution. The mechanical properties of both methods were examined, revealing that powder morphology significantly influences the mechanical performance. Tensile tests indicated that TiC-IN738LC composites prepared chemically exhibited a ductility of 3.26%, a 55% improvement over the ball-milled method, although their strength of 1416 MPa was marginally lower than the 1518 MPa achieved through ball-milled. Additionally, microstructural defects are mitigated by wet chemically mixing route. A high-fidelity Computational Fluid Dynamics (CFD) modelling was employed to investigate the effects of powder sphericity on melt pool dynamics, elucidating the mechanisms behind lack of fusion and verifying the influence of powder physical characteristics on the microstructure and mechanical properties. This study clarifies the role of powder morphology in determining the mechanical properties of nickel-based metal composites in L-PBF processes.