دگرگونيهاي فازي در فولادهاي زنگ نزن نيتروژن دار حين فرآيند آلياژسازي مكانيكي

Phase transformations in nitrogen-containing stainless steels during mechanical alloying process

In this research, phase transformations of Fe-18Cr-8Mn-xN stainless steel powders during mechanical alloying process under nitrogen gas atmosphere were studied. The results showed that by increasing the milling time, the proportion of volume fraction of austenite to ferrite phases rises, owing to increasing the solved nitrogen content in the structure. Finally, after 144 hours of milling, the only recognizable crystalline phase is austenite. On the other hand, the transmission electron microscopy picture of the powder milled for 144 hours showed that a secondary amorphous phase is formed next to the austenite phase, due to the increase of crystalline defects during mechanical alloying. The microstructure of the alloy consisted of the continuous amorphous phase and dispersed nanocrystalline austenite, remarking that the nucleation of amorphous phase has occurred along crystallite boundaries.