Effect of Mo content in amorphous Fe-Mo-C materials mechanically alloyed on their electrical and thermal properties

Amorphous Fe83-xMoxC17 (x=5-35) materials were prepared through mechanical alloying (MA) of elemental powder mixtures by use of a planetary ball mill. Using the conventional four-terminal arrangement, the electrical resistivity of the MA materials was measured during heating and cooling in the temperature range 300 K to 1100 K. The temperature coefficient of resistivity (TCR) during heating continuously varied with the value of x. With the increase in the Mo concentration x, the positive TCR during heating changed to negative near x=20. This corresponds to the Mo concentration indicating a marked change in the slope of the crystallization temperature Tx vs x curve depicted using differential scanning calorimetry (DSC) data of the MA samples. The resistivity during heating abruptly decreases at almost the same temperature as the temperature of Tx, determined by DSC, for all the MA samples and thereafter the value of TCR becomes positive for both the cooling and heating parts of the thermal cycle, as observed in usual crystalline metals. (orig.)