Evolution of submicrocrystalline iron containing dispersed oxides under mechanical milling followed by consolidation

The changes an pct alloy during milling by structural in Fe-0.6 pet O mechanical milling followed consolidation through rolling were studied. The iron-iron oxide powders were mechanically milled in an argon atmosphere for various times from 20 to 300 hours. The powders were then canned into a steel pipe and multiple rolled at 700 °C for consolidation. The microstructure of the final product depended significantly on the milling time. The volume fraction of the dispersed oxides (10 nm in diameter) increased from about 0.3 to 2.5 pct when the milling time was increased from 20 to 300 hours. The relatively short milling time of 20 hours resulted in the evolution of elongated grains (an average size of about 1.2 μm) with a large fraction of low-angle grain boundaries after consolidation. In contrast, much finer grains (about 0.2 μm in size) with a near random grain-boundary misorientation distribution evolved in the samples milled for 300 hours.