Resistivity of Fe-Mn-C Melts

The resistivity of liquid Fe-Mn-C alloys containing from 5 to 25 wt % manganese and from 0.4 to 2.2 wt % carbon has been measured by the rotating magnetic field method. The measurements have been made during heating from 1340 to 1810 degrees C and subsequent cooling of the samples. The resistivity of the melts during heating was considerably lower than that during subsequent cooling, which was accompanied by a decrease in the temperature coefficient of resistivity. The temperature dependence of resistivity for some of the alloys has been found to have an anomaly in the form of a break during heating to temperatures in the range 1550-1680 degrees C. The addition of manganese and carbon has been shown to influence the resistivity of the melts and its temperature coefficient. We have calculated the effective resistivity of a liquid alloy with the composition (wt %) Fe-10Mn-1C as a heterogeneous system using analytical relations for conductivity of inhomogeneous media, a unit-cell method, and geometric models of isolated and interpenetrating inclusions. The temperature t* = 1730 degrees C thus obtained for the transition from isolated to interpenetrating inclusions in the Fe-10Mn-1C melt agrees with the experimentally determined temperature t* = 1680 degrees C of the beginning of the portion common to the temperature dependences of resistivity obtained during heating and cooling. The temperature 1540 degrees C of the transition from isolated to interpenetrating inclusions agrees with the experimentally determined temperature 1550 degrees C corresponding to the break in the temperature dependence of resistivity.

Automated summary

The resistivity of liquid Fe-Mn-C alloys with varying manganese and carbon contents was measured using the rotating magnetic field method. It was found that the resistivity during heating was lower than during subsequent cooling, with some alloys showing anomalies in the temperature dependence of resistivity during heating between 1550-1680°C. The addition of manganese and carbon was shown to influence the resistivity and temperature coefficient of the melts.