Effect of the feeding rate on microstructure and properties of plasma spheroidized GH4169 powder

The growing interest in additive manufacturing of GH4169 alloy was accompanied by the demand on spherical GH4169 powders with high performance. The powder particles were treated by radio frequency plasma with the different feeding rates. The microstructure and morphology, the particle size distribution of as-treated powders were studied by scanning electron microscopy and laser particle size analysis. It was demonstrated that GH4169 powders with extremely fine followability were obtained by radio frequency plasma spheroidization technology. With the same plasma parameters, the spheroidization efficiency of the particles varied with the feeding rates. When the rate of the powder feeding rates was too small, the excessive absorption of the heating by the powders caused vaporization, then the collection decreased. When the feeding rates was too large, the powder particles were insufficiently absorbed, resulting in defects in the powders. The microstructure of the as-treated spherical particles was mainly cell crystals, columnar crystals, and even microcrystals. Under the suitable plasma parameters, the resulting powders haved a slightly increased average particle size, excellent spheroidization, surface smoothness, followability, and bulk ratio.