Structural and magnetic transformations in the Fe-Mn binary system

The phase transformations of five binary iron-manganese (Fe-Mn) alloys with manganese contents ranging from 1 to 21 weight percent have been characterized in the temperature range between room temperature and 1250 degrees C. Differential scanning calorimetry and dilatometry were used to experimentally characterize both the phases and magnetic transformation temperatures. X-ray diffraction and light optical microscopy were employed for the room temperature microstructure characterization. Depending on the manganese content of the alloy, three different crystal structures can be found: body centered cubic (bcc) (alpha/alpha '), face centered cubic (fcc) (gamma), and hexagonal compact (hcp) (epsilon). At manganese contents lower than 10% the phases present are the alpha/alpha ' (bcc) and gamma (fcc). Above similar to 10 weight percent manganese increasing amounts of epsilon (hcp) is formed at the expense of the body centered cubic structures, and no alpha/alpha ' (bcc) is observed for the 21 weight-percent manganese alloy.