Influence of niobium on laser de-vitrification of Fe–Si–B based amorphous magnetic alloys

• Laser annealing of amorphous soft magnetic Fe–Si–B–Cu–Nb (Finemet type) alloys
• Coupled influence of rapid heating and cooling and solute elements on de-vitrification
• Solute partitioning between nanocrystals and amorphous matrix during laser de-vitrification
• Magnetic properties of laser annealed soft magnetic alloys

Laser annealing of Fe77.5Si13.5B9 and Fe76.5Si13.5B9Cu1 amorphous melt-spun ribbons was carried out. In both alloys, it was found that devitrification occurred, leading to the nucleation of a high density of refined α-Fe(Si) nanocrystals within the amorphous matrix. Interestingly, when laser processed under identical conditions, Fe74.5Si13.5B9Nb3, and Fe73.5Si13.5B9Nb3Cu1 (FINEMET) amorphous melt-spun ribbons did not exhibit devitrification or copper clustering. Differences in the magnetic properties were observed, with the Fe77.5Si13.5B9 and Fe76.5Si13.5B9Cu1 alloys exhibiting higher saturation magnetization (MS) and higher coercivity (HC) values while Fe74.5Si13.5B9Nb3, and Fe73.5Si13.5B9Nb3Cu1 alloys exhibited lower values of both these properties. These results clearly reveal the enhanced stability of the amorphous phase due to the addition of Nb in Fe–Si–B based melt-spun samples.