CRYSTALLIZATION BEHAVIOR AND TEMPERATURE-DEPENDENCE OF THE INITIAL PERMEABILITY OF AN FECUNBSIB ALLOY

The crystallization behavior of an Fe73.5Cu1Nb3Si13.5B9 alloy was stud ied by differential scanning calorimetry. Two crystallization peak tem peratures at infinitesimal heating rate were obtained to be 769 K (T-x 1) and 910 K (T-x2), respectively. The associated activation energies by means of Kissinger's peak shift method were obtained to be 340 and 428 kJ/mole, respectively. Initial permeability (mu(i)) and Q values v ersus temperature was in situ investigated in the range from 300 to 87 3 K by a specially designed setup on toroid ribbon cores. Their variat ions with temperature reveal corresponding changes in magnetization an d nanocrystallization, etc. Anomaly mu(i) peaks at 428 K in the coolin g curve instead of at room temperature. By isothermal annealing at 823 K, precipitous maxima in mu(i) and Q appear at about 50 min. This in situ method may be too powerful to work out optimal annealing processe s for a specific nanocrystalline alloy. (C) 1997 American Institute of Physics.