Magnetic property improvement of melt spun LaCo5-based nanocomposites with Y, Fe and C substitutions

Magnetic properties, crystal structure, and microstructure of La1-xYxCo4.7-yFeyC0.3 alloys (x = 0-1; y = 0-0.5) prepared by melt spinning are reported. Very low coercivity (H-i(C)) of 0.2 kOe is found for LaCo4.7C0.3 ribbon due to the existence of large amount of magnetically soft LaCo13 (1:13) and La2Co7 (2:7) phases. Interestingly, Y substitution for La was found effective in suppressing the formation of impurity phases and stabilizing 1:5 phase. Y entrance into 1:5 phase increases the Curie temperature and improves saturation magnetization (4 pi M-s) and magnetocrystalline anisotropy field (H-a), simultaneously. Fine microstructure observed for all studied samples due to C-doping contributes to high H-i(C) and good squareness of demagnetization curve. The stabilized 1:5 phase and increased 4 pi M-s with Y substitution for La and fine microstructure due to C-doping give rise to significant improvement of the permanent magnetic properties. The magnetic properties of LaCo4.7C0.3 ribbons can be enhanced to remanence (B-r) = 4.2-5.4 kG,H- i(C) = 8.0-14.5 kOe, (BH)(max) = 3.6-6.6 MGOe for x = 0.25-1. Finally, for alloy with x = 0.5, Fe-doping could further improve magnetization and (BH)(max) of La0.5Y0.5Co4.7-yFeyC0.3 ribbons, from B-r = 4.4 kG and (BH)(max) = 4.4 MGOe for y = 0 to B-r = 4.7-4.8 kG and (BH)(max) = 5.0-5.1 MGOe for y = 0.3-0.4, respectively. The result of this study provides a significant way to largely improve magnetic performance of isotropic LaCo5-based nanocomposites. (C) 2019 Elsevier B.V. All rights reserved.