Coercivity Enhancement in ${\rm Zr}_{2}{\rm Co}_{11}$-Based Nanocrystalline Materials Due to Mo Addition

Abstract

The Mo-content dependence of structure and magnetic properties of ( , 2, 3, 4, 5) nanocrystalline materials has been studied. The samples consist of hard-magnetic and soft-magnetic Co phases. The substitution of Mo for Co restrains the formation of Co, raises the content of , and increases the mean grain size of . Therefore, the coercive force of the sample increases with x. A coercive force of 7.9 kOe, which is a highest value reported among Zr-Co alloys, was achieved for . The anisotropy field of remains almost unchanged with increasing Mo content.

Effect of boron doping on nanostructure and magnetism of rapidly quenched Zr2Co11-based alloys

“…[1][2][3][4][5] Alloys with the approximate stoichiometry Zr 2 Co 11 crystallize in cubic, orthorhombic, and rhombohedral structures, but only the rhombohedral phase, which is predicted to be metastable by formation-energy calculations, leads to significant coercivity. 3,5,6 The structures are basically dense-packed, with structural motifs reminiscent of that in SmCo 5 . 6 Rhombohedral Zr 2 Co 11 is a high-temperature phase, whereas the orthorhombic phase is more stable at low temperatures.…”

“…5,[7][8][9] The higher the quench rate, the larger the content of rhombohedral Zr 2 Co 11 and the more refined the nanostructure, both enhancing the coercivity. 3,8 However, binary Zr-Co ribbons have relatively low coercivities. There are several approaches to enhance coercivity in Zr 2 Co 11 .…”

“…5,[10][11][12] The addition of Si and B has a similar effect. 3 In particular, boron addition has been found to increase the coercivity of rapidly quenched Zr-Co materials, 13,14 but it is unclear how B addition affects the phase components and structural properties. First-principle calculations 15 are consistent with both B substituting for Co and B occupying "interruption sites" between the motifs.…”

Magnetic hardening of Zr2Co11:(Ti, Si) nanomaterials

“…[1,2] Rhombohedral Zr2Co11 is a hard magnetic phase whose formation requires a high cooling rate. [3] However, the coercivity (< 3 kOe) of the pure Zr-Co alloys is too low to further increase energy product, and elemental addition is a feasible way to modify the structure and to improve the magnetic properties of Zr-Co alloys.…”

Effect of annealing on nanostructure and magnetic properties of Zr2Co11 material

“…[11] The coercivity was further increased up to 7.9 kOe for the single-phase Zr2Co11 alloy due to Mo addition. [12] Up to now, few studies have been done on the effect of annealing condition on nanostructure and hard magnetism of the single-phase Zr2Co11 materials. In this letter, we report that annealing optimizes the nanostructure of the single-phase Zr2Co11 materials, and thus significantly enhances the coercivity and increases the saturation magnetization.…”