Effect of additions of phosphorous, boron, and silicon on the structure and magnetic properties of the melt-spun FePd ribbons

Abstract Formation of the L10 structure in FePd alloys doped with nonmetallic elements is studied on melt-spun and annealed samples. The melt-spun Fe41Pd41P18−x−yBxSiy (x = 0–14; y = 0, 6) ribbons were annealed at the temperatures of 400–650 °C for different holdings in the range from 5 min to several hours and studied by X-ray and thermomagnetic analysis and TEM. The saturation magnetization, Curie temperature of the L10 phase, and grain size of the melt-spun doped Fe41Pd41P18−x−yBxSiy ribbons decrease in comparison with those of the melt-spun binary FePd alloy. The refined grain structure results in enhancing coercivity. Among all as-annealed samples, the P addition favors the amorphization of the as-spun Fe41Pd41P18 ribbons and refines grains of the formed L10 phase, but decreases magnetization. Substitution of B for P gives rise to magnetization of the Fe41Pd41P18−x−yBx alloys, but decreases their coercivity. A partial substitution of Si for B at the same P content refines grains and enhances the coercivity without a decrease in the magnetization of the Fe41Pd41P4B8Si6 alloy. It is suggested that P and B atoms occupy interstitial sites in the L10 lattice in the iron plane, weakening the exchange interaction and decreasing the Curie temperature. The additions of P, B, and Si to the FePd alloy allowed us to obtain the Fe41Pd41P4B8Si6 ribbons with the coercivity of 1560 Oe, which is 2.6 times higher than that of the melt-spun ribbons of the FePd alloy.