Institute of Metals Division - Precipitation of Iron Oxide from Alpha Fe-O Solid Solutions

Precipitation of FeO from Fe-O solid solutions has been studied by metallographic methods. Such precipitation, which is visible, is composed largely of barely resolvable spheroidal particles. No metallographic evidence has been found for grain boundary oxide films. Oxygen diffusion into a iron does not occur chiefly by inter-granular penetration. IN an earlier communication' dealing with the solid solubility of oxygen in a iron, it was shown that under one set of conditions it was possible to show FeO precipitated from supersaturated solid solution. However, to assist in rationalizing the effect of an FeO second phase upon the mechanical properties of iron, it would be desirable to have more information on the possible modes of precipitation and on the thermal treatments required to produce precipitation.