Internal friction observation of the ɛ ↔ γ transformation in a Fe–Mn alloy

Abstract

The internal friction behavior of a quenched Fe–22 wt.% Mn alloy was investigated in the temperature range from room temperature to 260 °C using a multifunctional internal friction apparatus. It has been shown that an internal friction peak appears at about 215 °C (named as P H) on the heating curves and dynamic modulus has a minimum corresponding to the peak temperature. The P H peak does not appear at the temperature during subsequent in situ cooling and another internal friction peak presents at about 45 °C (named as P L) on the cooling curve. The P H peak temperature does not vary with vibration frequency, and thereby the peak has no relaxational features. Its height increases with decreasing vibration frequency and increasing heating rate, and there is a linear relationship of the peak height and T ˙ / f . It can be suggested that the P H peak during heating results from ɛ ↔ γ transformation and the P L peak during cooling corresponds to γ ↔ ɛ transformation for the quenched Fe–22 wt.%Mn alloy.