Laser spheroidization combined with coaxial powder feeding: A novel strategy for preparing spherical powders for additive manufacturing

Spherical powders are essential for ensuring the quality of parts produced via additive manufacturing (AM). However, powders prepared using traditional methods often suffer from wide particle size distributions , high impurity content , and poor sphericity , which hinder the advancement of AM. This study presents a novel laser spheroidization technique combined with coaxial powder feeding to produce high-quality spherical powders for AM. The spheroidization process was analyzed through multi-source observations and theoretical calculations. The effects of laser spot diameter , powder feed rate , and carrier gas flow on the powder spheroidization ratio were investigated. Using response surface methodology (RSM), the optimal processing parameters were determined as 8.35 mm, 2.0 g/min, and 2.0 L/min, respectively. Under these conditions, the spheroidization ratio of iron powder exceeded 96 %, with a sphericity close to 100 %. The spheroidized powder also exhibited excellent properties, including a narrow particle size distribution, absence of internal porosity defects, and high powder purity. The flowability of the iron powder improved significantly, from 31.4 s/50 g to 12.6 s/50 g. Moreover, this method is not limited to specific materials and is also effective for spheroidizing other powders, including dendritic nickel, reactive titanium alloy , and refractory tungsten carbide . This work offers an approach for fabricating high-quality spherical powders, providing innovative solutions to the challenges associated with traditional manufacturing methods.