Study on the Preparation of Metallic Aluminum Powder by Nitrogen Atomization

Metal additive manufacturing represents the most promising application for Three-dimensional printing systems. Gas atomization is an important method for the preparation of metal powders. In this work, aluminum powders were prepared via vacuum induction atomization. Morphology and microstructure were investigated. Results demonstrated that optimal atomization occurred at 3 MPa with a 2.5 mm delivery tube diameter, yielding powders with an average particle size of 63.8 μm and a sphericity of more than 90%. Variations in droplet size caused differential cooling rates, enabling rapidly solidified small droplets to adhere to incompletely cooled large droplets and form satellite spheres. Quantitative analysis confirmed a positive correlation between metal powder particle size and surface satellite spheres. Large droplets exhibited long cooling times, resulting in more pronounced dendritic microstructures. This study provides theoretical insights for the preparation of metal powders.