Thermal Stability and Soft Magnetic Properties of Novel Low-Coercivity Fe-B-Ce-La Alloys

In this study, FeSUBbal./SUBSUB/SUB BSUB16/SUB(CeLa)SUBx/SUB amorphous soft magnetic alloy ribbons with x ranging from 0 to 3.5 at.% were fabricated and the effects of Ce and La additions on their magnetic and thermal properties were analyzed. The fabricated ribbons were subjected to stress relief annealing at 375 °C for five minutes, and their microstructures were compared and analyzed using Electron Backscatter Diffraction. The saturation magnetization in the FeSUBbal./SUBBSUB16/SUB at.% ribbons decreased due to the atomic size differences among Fe, B, Ce, and La, while the coercivity stabilized at 20.75 A/m when the CeLa content exceeded 2.0 at.%. After stress relief annealing, further reductions in coercivity were observed, with the CeLa 3.5 at.% sample exhibiting the lowest coercivity of 12.74 A/m. When the CeLa content exceeded 1.5 at.%, the activation energy increased to over 515.41 kJ/mol, resulting in a stable reduction in coercivity and high thermal stability. In compositions with CeLa content of 2.0 at.% or higher crystallization did not occur, and as a result these alloys maintained low coercivity and high thermal stability and demonstrated excellent properties.