Alpha and Gamma Phase Sintering of Carbonyl and Other Iron Powders

Abstract

It is well known that carbonyl iron powders behave differently during sintering in comparison to commercially available electrolytic and reduced iron powders. This investigation of the sintering of carbonyl and other iron powders in the alpha and gamma range of iron has shown that the rate of densification and the sintered density of carbonyl iron powder is considerably greater than that of the two other types of iron powder. This is also true with respect to the actual values of strength and elongation. The changes in grain structure of carbonyl iron powder during sintering up to 2000°F are shown. Attempts have been made to explain the sintering behavior of carbonyl iron powder by the difference in the correlation between surface and volume diffusion and also between grain boundary and volume diffusion, which correlation differs from those for the larger electrolytic and reduced iron powders.