Textured anisotropic FePd/α-Fe nanocomposite foils by sheath repetitive cold-rolling

Fe-Pd (Fe55.5Pd44.5 and Fe50Pd50) nanostructured multilayered foils with average individual layer thicknesses decreased to 30 nm were fabricated by a sheath repetitive cold-rolling process. Fe and Pd have {0 0 1}Fe//{0 1 1}Pd out-of-plane texture in the as-rolled foils. With increasing the cold-rolling cycles up to nine, the intensities of {0 0 1}Fe//{0 1 1}Pd textures basically increase while the individual Fe/Pd layer thicknesses monotonically decrease. Textured anisotropic FePd/α-Fe nanocomposite foils were formed after being annealed at 450-600 °C for 2 h in a 19 T in-plane or out-of-plane magnetic field. It is suggested the nucleation adopts an orientation relationship of {0 0 1}Fe//{0 1 1}Pd//{0 0 1}FePd in the annealed samples. Magnetic anisotropy behavior was observed in the annealed FePd/α-Fe nanocomposites due to the textured nanostructure. A combination of higher intensity of (0 0 1) out-of-plane texture, finer nanoscaled grain sizes and more sufficient solid-state phase transformation resulted in higher values of both coercivity μ0Hc and maximum energy product (BH)max in the FePd/α-Fe nanocomposites. The texture and magnetic anisotropy behaviors were similar in both Fe-Pt and Fe-Pd alloys. Due to the textured nanostructures, (BH)max of Fe50Pt50 foil is higher by 8.5% than that of the theoretical limit of non-exchange-coupled isotropic FePt.