Study on Powder Characteristics and Droplet Size Influence Factor in Electrode Induction Melting Argon Atomization

Abstract:

Abstract: In this paper, we investigated the physical characteristics, solidification microstructure, and inter element distribution of Ni-based superalloy powders, which prepared by electrode induction melting gas atomization (EIGA) process. Some factors on metal droplet size during primary atomization were also deeply analyzed. The cooling rate of different size powders were calculated through convective heat transfer principle. It is found that the EIGA powders are mainly spherical, the Hall flow rate is 13.4s/50g, and the D90 is 121.5μm. The microstructure of powders on surface and internal changes from microcrystals to cell crystals and dendrites increasing with the powder size. At the same time, the smoothness of powders decreases as the gap increases on the surface. The relationship between cooling rate and particle size is |〖dT〗_d/dt|=〖8.98*10〗^(-5)/d^2 , when the atomization gas pressure is 4MPa. There is slightly segregation in crystal axis and intercrystal of powders. The content of Ni, Al, Co, and C in crystal is higher than intergranular, while the content of Ti, Mo, Cr, and Nb in intergranular is much higher.

Key words:superalloy powder, primary atomization, segregation, liquid film, cooling rate