Effect of Al and Cu Additions on Microstructure and Magnetic Properties of NdTb-FeCo-B Magnets

Abstract

With the addition of Al and/or Cu into the NdFeB based magnet, the soft free iron phase was not observed in the cast alloys while it exists in the microstructure of the undoped NdFeB ingots. For the undoped sample, free iron disappeared after hot deformation process. Grain orientation is not good and there are deviations in the growth direction of the lamellar grains which are not perpendicular to the pressing direction. On the other hand, there is a striking change that the intergranular chemistry of Al added ingot separated into Nd-rich phase and a ternary FeNdAl composition most probably formed at the pressing temperature of 750• C. The highest remanent magnetization of 7.47 kG obtained for this sample, it might be due to the hard magnetic properties of this ternary composition. For the AlCu added sample, the high Hc and Br values of 7.71 kOe and 7.33 kG, respectively, can be attributed to the homogeneous distribution of the intergranular composition and good orientation of the magnetic grains by hot deformation process.

First-principles study of crystalline Nd–Fe alloys

“…In calculating the Nd 0.67 -M Fe y y 0.33 alloys, we adapted a 2 × 2 × 2 supercell with 96 atoms, where Fe 4a sites are replaced with M. The sites occupied by M are chosen by the SQS method. Figure 3 illustrates the 21). In all the cases, the formation energy is lower than the case of the binary alloy Nd 0.67 Fe 0.33 with the fluorite structure.…”

“…18,19) Recent investigations have demonstrated that doping of metallic elements such as Al, Co, Cu, and Ga greatly modifies the microstructure including the GB phase improving the coercivity. [20][21][22][23] In this sense, the atomic configurations and the magnetism of the GB phase is of significant importance.…”

SYNTHESIS POLYMER MATRIX COMPOSITE EPOXY FeNdB-Cu FOR RADAR ABSORBER COATING APPLICATION

“…The requirement for the radar absorber itself is that it must have a narrow hysteresis loop with the smallest possible coercivity value <0.2 kOe and the highest possible saturation value . [8,9]. The increase in the coercivity value is due to the failure of Cu ions to substitute Fe ions due to the presence of cracks in the material as mentioned by Callister [10] that the coercivity value is sensitive to structural changes.…”

Jet electrodeposition multilayer nickel on the surface of sintered NdFeB and corrosion behaviours

“…This phenomenon results in serious inter-granular corrosion [7][8], thereby causing performance failure. To improve the corrosion resistance of NdFeB material, numerous approaches have been employed, such as adding alloying elements and producing protective film layer on NdFeB substrate [9][10][11][12][13][14][15][16]. The addition of alloying elements, like Zn and Sn, can certainly improve the corrosion resistance of NdFeB magnets, but usually with the effect of altering the metallurgical structure of NdFeB and thus tends to degrade the magnetic properties [11][12].…”

“…To improve the corrosion resistance of NdFeB material, numerous approaches have been employed, such as adding alloying elements and producing protective film layer on NdFeB substrate [9][10][11][12][13][14][15][16]. The addition of alloying elements, like Zn and Sn, can certainly improve the corrosion resistance of NdFeB magnets, but usually with the effect of altering the metallurgical structure of NdFeB and thus tends to degrade the magnetic properties [11][12]. Electroless depositing Ni-P multilayer on NdFeB substrate can improve the corrosion resistance, whereas, the process is more complex [13]; Electrodepositing alloys on NdFeB substrate such as Ni-Cu, Ni-Zn, which can not only improve its corrosion resistance but also reduce the loss of its magnetism [14][15][16].…”