Electrical resistance and crystallization characteristics of Fe80B20

The electrical resistance of amorphous Fe80B20 has been measured as a function of time at various temperatures during an isothermal crystallization process. The results fit a universal curve when ΔR/ΔRI is plotted against t/tI. The value of tI as a function of annealing temperature fits the Johnson-Mehl-Avrami equation with n = 3 changing to 1.4 for t/tI≳1.4. The resistance of a series of partially crystallized samples was measured between 4.2 and 300 K. dR/dT at 300 K and dR/dlogT below the resistance minimum were both found to be linear funtions of ΔR/ΔRI. That is, both the above quantities were found to be strictly proportional to the amount of crystalline phase present. This may pose some difficulty for the structural tunneling model of the low temperature resistance minimum in metallic glasses.