Mechanical alloying, usually the blending together of elemental metal powders, has been used successfully to produce nonequilibrium microstructures. In this Bureau of Mines study, the effect of mechanical processing on powders in reactive (nitrogen) and nonreactive (argon) gas atmospheres was investigated and compared to results for similar powders that had nitrogen diffused into them. Infusion of nitrogen into powder by mechanical processing resulted in a nitrogen concentration exceeding 1 wt pct, 20 times the as-cast solubility in pure iron. Even at these high concentration levels, no nitrides formed. The nitrogen remained in solution even after consolidation by hot isostatic pressing ("hipping"). The presence of nitrogen retarded grain growth during consolidation.