Effect of rotating speed on characteristic of IN625 alloy powders prepared by plasma rotating electrode process

To systematically reveal the influence of rotating speed on the particle size distribution and powder properties of IN625 alloy powders prepared by plasma rotating electrode process (PREP), five rotating speed levels ranging from 18000 to 28000 r·min^‒1 were set for PREP experiments. The results indicate that as the rotating speed increases, the particle size distribution undergoes a structural transformation: the proportion of fine powders (‒270 mesh, mass fraction) increases from less than 15% to over 60%, while the span of particle size distribution gradually narrows. The dominant role of ligament disintegration mode in the atomization process is significantly enhanced with increasing rotating speed, and the more sufficient ligament disintegration directly promotes powder refinement. The powder sphericity remains above 0.96 throughout, but the defect type changes from the elongated irregular particles caused by insufficient ligament disintegration at low rotating speed to the satellite particles formed by collision and adhesion of fine and medium particles at high rotating speed. As the rotating speed increases, the oxygen and nitrogen contents (mass fraction) of the as-produced IN625 powders increase slightly, while the flowability and apparent density decrease modestly, which is partially related to the increased proportion of fine powders (−270 mesh). The suitable rotating speed windows were identified for the different particle size requirements: the rotating speeds≥24000 r·min^‒1 can achieve a relatively high proportion of fine powders, while 18000~22000 r·min^‒1 is favorable for obtaining the as-produced powders with the excellent flowability and apparent density.