Abstract
The results of the research work concerning the rapid solidification of undercooled liquid droplets into small powder particles are presented. The iron base ledeburitic type alloy with 2.3% C, 4% Cr, 2% W, 7-8% V, 10-11% Co, 8% Mo chemical composition has been subjected to the experimental evaluation. Hypoeutectic solidification mechanism has been determined in the specimen obtained by 10 K.min^-1 cooling rate and also in RS powder with a particle size more than 100 µm. With the increase in cooling rate represented by a decrease in powder size, the change in the mentioned mechanism to the hypereutectic one has been determined. As such, the microstructure of a material is characterized by occurrence of small primary carbides in the centres of eutectic colonies. The changes in phase composition as a function of powder particle size have been also found in RS material.

Key words
iron base ledeburitic type alloy, solidification mechanism, RS material

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