Crystallization behavior and temperature dependence of the initial permeability of an FeCuNbSiB alloy

The crystallization behavior of an Fe73.5Cu1Nb3Si13.5B9 alloy was studied by differential scanning calorimetry. Two crystallization peak temperatures at infinitesimal heating rate were obtained to be 769 K (Tx1) and 910 K (Tx2), respectively. The associated activation energies by means of Kissinger close-quote s peak shift method were obtained to be 340 and 428 kJ/mole, respectively. Initial permeability (μi) and Q values versus temperature was in situ investigated in the range from 300 to 873 K by a specially designed setup on toroid ribbon cores. Their variations with temperature reveal corresponding changes in magnetization and nanocrystallization, etc. Anomaly μi peaks at 428 K in the cooling curve instead of at room temperature. By isothermal annealing at 823 K, precipitous maxima in μi and Q appear at about 50 min. This in situ method may be too powerful to work out optimal annealing processes for a specific nanocrystalline alloy. copyright 1997 American Institute of Physics