Magnetic Properties of Interference Pulsed Laser Heated Fe-Based Amorphous Ribbons

Abstract

The influence of pulsed laser interference heating on structure and magnetic properties of Fe-based (FeSiB) amorphous ribbons is reported. This form of heating results in periodically placed laser heated micro-areas. In these, changes in microstructure and magnetic properties occur and the results are compared with those for samples after conventional annealing at 600 • C. Electron microscopy showed that the laser beam energy causes partial crystallization of the amorphous material, which affects magnetic properties. Magnetic hysteresis loop measured by SQUID magnetometer showed that saturation magnetization σ lowered after both treatment (i.e., conventional annealing and laser heating) in comparison to amorphous ribbons (where the range of σ was from 155 to 185 emu/g), except for FeCuSiB alloy after laser heating. Magnetic structure of all the samples was also observed by magnetic force microscopy. While no signal was detected in the as-received amorphous ribbons, conventional annealing and laser heating resulted in strong magnetic signals.

Influence of Pulsed Interference Laser Heating on Crystallisation of Amorphous Fe77Cu1Si13B9 Ribbons

“…This is undesirable because of the deterioration of the magnetic properties. However, as reported in our works [6,33], Fe 77 Cu 1 Si 13 B 9 ribbons subjected to laser heating showed a higher saturation magnetisation (170 emu/g) compared to the material subjected to conventional crystallisation (156 emu/g) and compared to the material provided as an amorphous ribbon (163 emu/g).…”

“…An increase in the energy and the number of pulses led to too much melting and laser ablation processes (evaporation of the material). The changes obtained in the micro-areas corresponded to those obtained for FeSiB ribbons, which were discussed in our previous publications [6,33].…”

“…However, the appearance of ripples in the peripheral area denotes the crystallisation of the amorphous material, creating nanocrystals grouped in the form of 'wedges' in this zone. Due to the presence of the nanocrystalline structure, the magnetisation of the ripples area is to be expected compared to the amorphous matrix, as confirmed by the magnetic force microscopy studies discussed in our previous work [6,33].…”

“…The nanocrystalline structure enables an improvement in soft magnetic properties through low magnetic loss due to magnetisation reversal, high magnetic permeability, and low magnetostriction [39][40][41]. Changes in the magnetic properties of ribbons before and after laser heating (magnetic hysteresis loops, magnetic force microscopy) were discussed in our previous articles [6,33].…”