Improvement of the microstructure and magnetic properties of (La,Ce)–Fe–B nanocrystalline ribbons

The obstacles of inferior microstructure and poor magnetic properties of (La,Ce)–Fe–B type magnets stand in the way of expanding their applications. In this work, (La,Ce)–Fe–B melt-spun ribbons were prepared with different La/Ce ratios and rare earth contents. The microstructure and magnetic properties of these ribbons were investigated. With the La/Ce ratio increased, the fraction of the CeFe₂ phase decreased and the β-La phase segregated among matrix grains, which deteriorated the coercivity of the ribbons. Reducing the rare earth content effectively suppressed the β-La phase and improved the proportion of the matrix phase in the ribbons. Here, the optimal alloy composite (La₁₅Ce₈₅)₁₄Fe₈₀B₆ has been obtained with modified microstructure and inhibited secondary phases. Good ribbon performance was tested, with H_cj = 4.51 kOe, B_r = 6.29 kG and (BH)_max = 6.81 MGOe.