Non-isothermal Primary Crystallization Kinetics of the Amorphous Fe85.3B11P3Cu0.7 Alloy

Abstract

In the present research, the primary crystallization kinetics of the amorphous Fe85.3B11P3Cu0.7 alloy was analyzed using non-isothermal DSC measurements. The average and local activation energies, Ea, were determined by different isokinetic and isoconversional methods. The results obtained for activation energy in this research, show that due to the complexity of the primary crystallization process in this alloy, isoconversional methods are more suitable than the isokinetic ones. The Avrami exponents lie between about 1 and 2 in a wide temperature range of 370˂T≤410˚C. This indicates that one dimensional growth of nuclei with a decreasing rate of nucleation is the main mechanism during non-isothermal primary crystallization process of the amorphous Fe85.3B11P3Cu0.7 alloy which is a new finding for this alloy. Study of magnetic properties in the amorphous and nanocrystalline states revealed that annealing the amorphous ribbons at 440˚C for 10 minutes gives rise to a significant increase in saturation magnetization, Ms, i.e. from 144 in as-spun to 201 emu/g in annealed states. This amount of Ms makes this material a good candidate for different applications, especially in transformer cores.

Keywords

• avrami exponent
• crystallization kinetics
• isoconversional methods
• isokinetic methods