ON THE MECHANISMS OF NITROGEN SORPTION DURING ATOMIZATION OF MOLTEN ALLOYS

The mechanisms of nitriding during atomization of molten iron and cast iron with nitrogen and subsequent cooling of the powders in oil and n itrogen are studied. The amount of nitrogen absorbed by the melt dropl ets during atomization is determined mostly by the solubility of nitro gen in the melt. On solidification, a part of nitrogen forms nitrides, the remaining part is dissolved forming a superequilibrium solid solu tion. The amount of nitrogen in the solid solution increases with the cooling rate. With the powders cooled in nitrogen, solid-phase nitridi ng processes dominate and their role increases with the increase of th e specific surface of the powder. The lower rate of gas cooling compar ed with liquid cooling promotes the formation of a structure closer to equilibrium and the appearance of strong-bonded nitrogen containing c ompounds. A part of nitrogen is retained in the adsorbed form. The nit rogen-content of the powders decreases on storage owing to desorption.