Stimulating the amorphous structure of Fe56Co24Nb4B13Si2Cu1 ferromagnetic alloy by thermal annealing, laser and electron beam irradiation: A Mӧssbauer spectroscopy investigation

Abstract

This study presents a Mӧssbauer spectroscopy investigation of the Fe56Co24Nb4B13Si2Cu1 amorphous ferromagnetic alloy in the as-quenched state and after thermal annealing, laser and electron beam irradiation. Thermal treatment at temperatures of 450–750° C caused nano, partial and complete crystallization of the alloy system. Crystalline phases such as α-(FeCo), (FeCo)2(BSi) and (FeCo)3(BSi) were identified in the thermally annealed specimens. By analyzing the hyperfine magnetic field distributions, it was shown that continuous wave (cw) CO2 laser irradiation of fresh samples determined a more pronounced in-plane orientation of magnetic moment directions and caused changes in the chemical short-range order in the system with non-zero magnetostriction. For direct comparison, atomic rearrangements were not observed in the Fe68.5Co5Nb3Cu1Si15.5B7 ferromagnetic alloy having a zero magnetostriction constant. Unlike the case of laser annealing, irradiation with 11 GeV electrons of the Fe56Co24Nb4B13Si2Cu1 alloy determined a pronounced out-of-plane magnetic anisotropy and supported the formation of stress centers in the irradiated system. Both laser and electron beam irradiation were found to essentially preserve the amorphous phase of the processed alloy.

Keywords

• Amorphous ferromagnetic alloys
• Thermal annealing
• Laser irradiation
• Electron beam irradiation
• Mӧssbauer spectroscopy