Characteristics of the γ→α transformation in Fe–Mn alloys

The relationships between the lattice parameters of austenite and ferrite in Fe–Mn alloys and Mn content were established by means of X-ray diffraction and revised literature data. These results were used to calculate the dilatation due to the isothermal γ→α transformation. The dilatometric experimental results are in very good agreement with the calculations. It was found that the increase of hardness of the α phase is a linear function of Mn content and is mainly determined by the lattice strain of this phase. The Curie temperature of the alloy was established as a function of Mn composition. The austenite fraction and enthalpy difference between ferrite and austenite accompanying the γ→α transformation were also determined as a function of temperature and Mn content by means of isochronal DTA measurements.