Comparison of Powder Mixing Methods for Metal Matrix Composite Powders Used In Laser Powder Bed Fusion

Metal matrix composites (MMCs) reinforced with different types of particles offer enhanced mechanical properties for high-performance applications. Laser Powder Bed Fusion (LPBF), has become an innovative way to fabricate these materials, offering light-weight structures and rapid prototyping. In this work, we investigated the impact of three different powder mixing techniques, namely, acoustic, tumbler, and ball milling for mixing of TiC particles with Inconel 625 powders. Meanwhile, micron and nano-sized particles were separately studied to examine particle size effect on reinforcement distribution during powder mixing. With this approach, we aimed to achieve homogeneous dispersion of different size of reinforcements for Inconel 625 while maintaining the spherical morphology of matrix powders. Powder characteristics such as flowability, apparent density, and tap density based on particle size, content and mixing parameters for each method were analyzed. Results revealed that acoustic mixing process achieved uniform dispersion of TiC particles with minimal agglomeration and maintained the spherical shape of the matrix powders. In comparison, ball milling resulted in surface deformation and clusters in mixed powders, while tumbler mixing caused significant agglomeration of reinforcements. The addition of particles and mixing operations lead a slight decrease in flowability of composite powders due to rougher surface texture compared to original Inconel 625 powder. The powders processed with acoustic system showed more enhanced flow properties among these methods and indicated the lowest Hausner ratio. Furthermore, we successfully produced fully dense samples using the powders prepared via acoustic mixer, proving their suitability for LPBF. This work demonstrates the potential use of acoustic mixing as an efficient and a scalable method to produce high-quality MMC powders with enhanced dispersion while meeting the requirements of LPBF processes.