Phase modification and magnetic property improvement in melt spun LaCo5-based ribbons

Magnetic properties of melt spun LaCo5-based ribbons are remarkably improved by phase modification and grain refinement with M (M = Ti, Zr and Hf) substitution for Co in LaCo5 and R (R = Ce, Pr, Nd, Sm, and Y) substitution for La in LaCo4.7C0.3, respectively. Because of the coexistence of considerable amount (similar to 42-70 vol%) of soft magnetic La2Co7 (2:7) and LaCo13 (1:13) phases with LaCo5 (1:5) phase, small coercivity (H-i(c)) of 0.8 kOe and 0.3 kOe are found in LaCo5 and LaCo4.7C0.3 ribbons, respectively. A slight Ti, Zr, or Hf substitution for Co in LaCo4.9M0.1 ribbons is helpful to effectively decrease the amount of soft magnetic phases (down to similar to 3.1-5.6%) and refine the grain size of 1:5 phase, and therefore improves the H-i(c) and the squareness of demagnetization curve. H-i(c) of the ribbons is significantly improved to 8.1-11.6 kOe. On the other hand, R substitution for La in La1-xRxCo4.7C0.3 ribbons is also effective in obtaining large amount of 1:5 phase (82.8-86.2 and 90.8-97.5% for x = 0.25 and 0.5, respectively). R entrance into 1:5 phase modifies the magnetization, magnetocrystalline anisotropy field, and Curie temperature, simultaneously. In addition to large amount 1:5 phase, fine size of the grains for La1-xRxCo4.7C0.3 samples related to C-doping also contribute to enhance magnetic properties, especially large and good squareness of demagnetization curve. Magnetic properties of La1-xRxCo4.7C0.3 ribbons are mainly dominated by their corresponding phase constitutions and the magnetically intrinsic properties of RCo5 phase. Accordingly, we attain the attractive magnetic properties of H-i(c) = 15.1 kOe and (BH)(max) = 3.8 MGOe for La0.5Ce0.5Co4.7C0.3; = 10.3 kOe and (BH)(max) = 4.4 MGOe for La0.5Y0.5Co4.7C0.3 and H-i(c) = 15.8 kOe and (BH)(max) = 5.2 MGOe for La0.5Sm0.5Co4.7C0.3, respectively. This study provides the effective way to improve magnetic properties of isotropic melt spun LaCo5-based ribbons by phase modification and grain refinement. [GRAPHICS] .

Automated summary

The magnetic properties of melt spun LaCo5-based ribbons can be significantly improved by modifying the phases and refining the grains, resulting in reduced coercivity and enhanced squareness of the demagnetization curve. Substitution of elements M (M = Ti, Zr, Hf) for Co and R (R = Ce, Pr, Nd, Sm, Y) for La in the compositions also contributes to the enhancement of magnetic properties.