The kinetics of crystallizing amorphous Fe80B20, Fe80B15P5 and Fe80B 10P10 alloys were monitored by isothermal electrical resistance measurements. These isothermal measurements generally displayed an initial transient where the electrical resistance increased with annealing time. The transient was followed by two apparent annealing stages where the resistance decreased with annealing time. The magnitude of the transient was dependent on the boron content and the transient appeared to be responsible for the characteristic anneal embrittlement of these alloys. X-ray diffraction results indicated that no crystallization occurred during the transient and that the alloys crystallized during the subsequent annealing stages. The kinetics of both annealing stages were found to obey the general relationship F = exp (t/τ)n, where F is the reciprocal volume fraction not crystallized, n is a coefficient and τ is a rate constant that obeys the Arrhenius relationship. The coefficient n and the activation energy Q were determined from the isothermal annealing data. For the first stage, the coefficient has a value of 1.3 for Fe80B20 while the activation energy was compositionally dependent being 44, 55, and 55 Kilocalories/mole for the Fe80B20, Fe80B 15P5, and Fe80B10P10 alloys respectively. The second annealing stage had a coefficient of 0.5 for Fe80B20.
