Study of nitrogen effect on the mechanical alloying process and subsequent heat treatment of Fe-14 wt.% Mn powders

In the present work, the effect of nitrogen on the mechanical alloying process and subsequent heat treatment of Fe-14 wt.% Mn powders was studied. The mechanical alloying was carried out in a SPEX 8000D mill under Ar and N-2 atmospheres. The microstructural and morphological characterization of the powders was determined through X-ray diffraction and scanning electron microscopy. The study of the thermal stability of the mechanically alloyed powders was conducted utilizing differential scanning calorimetry. The results indicated that the milling atmosphere does not influence the phases detected after 10 h of mechanical alloying. After this milling time, the presence of two solid a Fe-Mn solutions with different manganese content was observed. In terms of morphology, powders milled under Ar atmosphere presented a more lamellar aspect than powders milled in a N-2 atmosphere. Regarding the distribution of sizes, it was determined that at initial milling times, a relative increase in the size of the agglomerates occurs as a result of the prevalence of the weld over the fracture. This trend is reversed to higher milling times. Concerning the study of thermal stability of the mechanical alloyed powders, it was determined that N-2 favors the formation of the. Fe-Mn phase.