Phase separation in the Fe–Mn system

Structure, magnetostrictive, and magnetic properties of heat-treated Mn42Fe58 alloys

“…However, recently, it has been reported [4] that due to the positive deviation from the Raoult's law for Fe-9-80 at.% Mn alloys, the solidsolution region in the Fe-Mn diagram at 700-1200 • C is in fact a phase-separation region and Mn distribution is inhomogeneous. Therefore, it is considered that the Mn 42 Fe 58 sample has separated into a Mn-enriched and a Mn-depleted region during the isothermal heat treatment at 1100 • C. And the high-temperature Mn-deficient austenite transforms to martensite and ␣-phase during cooling.…”

“…Therefore, it is considered that the Mn 42 Fe 58 sample has separated into a Mn-enriched and a Mn-depleted region during the isothermal heat treatment at 1100 • C. And the high-temperature Mn-deficient austenite transforms to martensite and ␣-phase during cooling. In addition, since ␥-Mn-Fe alloys have a tendency towards homogenizing as the temperature decreases [4], the phase separation in Mn 42 Fe 58 alloy at 1100 • C cannot be preserved completely to low temperature by furnace cooling at a relatively slow cooling rate due to the sufficient time for the Mn atom diffusion. Thus, water quenching is helpful for the formation of multiphase structure.…”

“…In contrast, little researches have been done on Mn-Fe alloys with higher Mn content, because it was believed that the alloys only exhibited a single austenite structure even after various heat treatments [3]. However, a minor quantity of martensite and ␣-phase has been found in quenched 40.3 at.% Mn-Fe alloy after long-term isothermal heat treatment at temperatures ranged from 700 to 1200 • C, which can be contributed to the phase separation of ␥-phase at high temperatures [4].…”

A New Paradigm for Metallic Alloys in Materials Science

“…Тhe structure of such chemical domains has been found up to now in alloys of the Fe-Cr system. Therefore, in alloys of other binary systems studied (Fe-Co [9], Fe-Mn [26], Fe-Ti [27], Fe-V [28], Fe-Mo [29], Fe-W [30]), the temperature of the phase transition "ordering-phase separation" was determined by the change in the type of the microstructure.…”