Effect of melt delivery nozzle parameters on Fe–Cr alloy powders prepared by vacuum close-coupled gas atomization

Fe–Cr alloy powders were prepared by vacuum close-coupled gas atomization technology. The effects of the diameter and protrusion length of the melt delivery nozzle on the size distribution, yield, and median particle size (D₅₀) of the Fe–Cr alloy powders were studied. The results show that, when the diameter of the melt delivery nozzle increases from 4.5 mm to 6.0 mm, the size accumulation distribution curve of the Fe–Cr alloy powders shifts to the right, the median particle size increases, the fine powder yield decreases, the powder fluidity decreases, and the apparent density decreases. When the protrusion length of the melt delivery nozzle increases from 2.0 mm to 2.5 mm, the size accumulation distribution curve of the Fe–Cr alloy powders shifts to the left, the median particle size decreases, the fine powder yield increases, the powder fluidity increases, and the apparent density increases. Combined with the experimental data analysis, the best comprehensive properties of the Fe–Cr alloy powders are obtained under the condition as the atomization pressure of 3.8 MPa, the superheat of 250 ℃, the nozzle diameter of 4.5 mm, and the nozzle protrusion length of 2.5 mm.