MICROSTRUCTURE OF RAPIDLY SOLIDIFIED IN-100 POWDERS

Powder particles generated by the RSR centrifugal atomization process exhibit at least two distinct types of microstructure. When a high melt superheat is maintained during atomization, the powder particles possess the familiar coarse grained dendritic microstructures. On the other hand, when the melt superheat is reduced by increasing the heat flow to the disc of the rotary atomizer, the powder particles are predominantly microcrystalline in character, with typically one small dendrite particle per grain. It is proposed that the unusual microcrystalline material has its origin in dendrite erosion occurring in a mushy zone" of dynamic solidification on the disc of the atomizer. © 1979 American Society for Metals and the Metallurgical Society of AIME."