Structural evolution during mechanical alloying of stainless steels under nitrogen

Mechanical alloying of Fe-based powders under a nitrogen atmosphere has been recently converted into the subject of many researches. This paper reviews aspects of mechanical alloying of stainless steels under a nitrogen atmosphere. Nitrogen incorporation from the viewpoints of infusion mechanism, supersaturation, and kinetics is considered. The structural refinement, leading to nanocrystallization, and phase transformations, consisting of austenitization and amorphization, are outlined. Particularly, it is noted that nitrogen intensifies grain refinement and proceeds ferrite-to-austenite phase transformation and amorphization during mechanical alloying.