Magnetic Domain Structure of Nanocrystalline Zr_18-xHf_xCo₈₂ Ribbons: Effect of Hf

Abstract

The effect of Hf on the permanent magnetism of nanocrystalline Zr 18-x Hf x Co 82 ribbons (x = 0, 2, 4, and 6) was investigated by magnetic properties measurement and magnetic force microscopy (MFM). Emphasis is on the local magnetic domain structures in polycrystalline rapidly solidified Zr 18-x Hf x Co 82 ribbons for four different samples with small fractions of Hf dopants (x ≤ 6). The investigation of the magnetic properties of the Zr 18-x Hf x Co 82 ribbons revealed that all the samples under investigation are ferromagnetic at room temperature, and the corresponding MFM images show bright and dark contrast patterns with up-down magnetic domain structures. It is found that the saturation magnetization and the coercivity depend on Hf doping concentration x in the samples. For a sample with Hf concentration x = 4, the maximum energy product (BH) max value is 3.7 MGOe. The short magnetic correlation length of 131 nm and smallest root-mean-square phase shift value of 0.68 0 were observed for x = 4, which suggests the refinement of the magnetic domain structure due to weak intergranular exchange coupling in this sample. The above results indicate that suitable Hf addition is helpful for the magnetic domain structure refinement, the coecivity enhancement, and the energy-product improvement of this class of rare-earth-free nanocrystalline permanent-magnet materials.

Magneto-mechanical Effect on the Magnetic Properties and Microstructures in Nanocrystalline Fe-Cu-Nb-Si-B Alloys

“…[4] Such produced ribbons enabling efficient usage in many electronic and electromechanical circuits have been widely investigated in terms of both magnetic properties [1,[5][6][7] and microstructures. [8][9][10][11][12] NC FeCuNbSiB alloys are commonly known by the lowest coercivity, H c (< 1 A/m), a fulfilling permeability, l (> 1 9 10 5 ), a very low magnetostriction, k s (< 1 ppm), and a sufficient saturation polarization, B s (% 1.25 T). [1,2,13] Knowing the composition of NC alloys would be a significant source for making a prediction regarding their magnetic behavior and crystallization temperature based on their Fe content percentage.…”