High Intrinsic Coercivity Research Articles

Increase of coercivity and composition distribution in dysprosium-diffused NdFeB sintered magnets treated by vacuum evaporation method

This study examines the distribution of heavy rare-earth elements (HRE) and magnetic properties in sintered NdFeB permanent magnets treated with Dy vacuum evaporation grain boundary diffusion, considering variations in time and temperature. The HRE distribution and magnetic properties were analyzed using an electron probe microanalyzer (EPMA), glow discharge optical emission spectrometer (GDOES), and hysteresis loop meter. The optimal temperature gradient for achieving the best results was found to be between 850 °C and 950 °C for a duration of 10 h. This resulted in iHc of 1415 kJ/m and (BH)max of 396.2 kJ/m3, which is classified as N52H grade. In comparison, the untreated NdFeB magnets had iHc of 1105 kJ/m and (BH)max of 400.3 kJ/m3, classified as N52 M grade. The results suggest that 0.167 wt% consumption of vacuum evaporated Dy alloy can enhance the 28 % in iHc of the magnet and 5 % increase in (BH)max compared to the untreated ones. This innovative manufacturing method improves the utilization of rare heavy earth and enhances the overall magnetic properties. This material has the potential to be used in the development of low-weight rare earth-sintered NdFeB magnets with high intrinsic coercivity. This study's findings advance energy-efficient technologies such as electric vehicles and offshore wind turbines, aiding global energy conservation efforts.

Batch Fine Magnetic Pattern Transfer Method on Permanent Magnets Using Coercivity Change during Heating for Magnetic MEMS.

In magnetic microelectromechanical systems (MEMSs), permanent magnets in the form of a thick film or thin plate are used for structural and manufacturing purposes. However, the geometric shape induces a strong self-demagnetization field during thickness-direction magnetization, limiting the surface magnetic flux density and output power. The magnets must be segmented or magnetized in a fine and multi-pole manner to weaken the self-demagnetization field. Few studies have been performed on fine multi-pole magnetization techniques that can generate a higher surface magnetic flux density than segmented magnets and are suitable for mass production. This paper proposes a batch fine multi-pole magnetic pattern transfer (MPT) method for the magnets of MEMS devices. The proposed method uses two master magnets with identical magnetic patterns to sandwich a target magnet. Subsequently, the coercivity of the target magnet is reduced via heating, and the master magnet's magnetic pattern is transferred to the target magnet. Stripe, checkerboard, and concentric circle patterns with a pole pitch of 0.3 mm are magnetized on the NdFeB master magnets N38EH with high intrinsic coercivity via laser-assisted heating magnetization. The MPT yields the highest surface magnetic flux density at 160 °C, reaching 39.7-66.1% of the ideal magnetization pattern on the NdFeB target magnet N35.

Enhancing Intrinsic Magnetic Hardness by Modulating Antagonistic Interactions in the Rare-Earth-Free Magnetic Solid Solution Hf2 Fe1-δ Ru5-x Irx+δ B2.

The quinary members in the solid solution Hf2 Fe1-δ Ru5-x Irx+δ B2 (x=1-4, VE=63-66) have been investigated experimentally and computationally. They were synthesized via arc-melting and analyzed by EDX and X-ray diffraction. Density functional theory (DFT) calculations predicted a preference for magnetic ordering in all members, but with a strong competition between ferro- and antiferromagnetism arising from interchain Fe-Fe interactions. The spin exchange and magnetic anisotropy energies predicted the lowest magnetic hardness for x=1 and 3 and the highest for x=2. Magnetization measurements confirm the DFT predictions and demonstrate that the antiferromagnetic ordering (TN =55-70 K) found at low magnetic fields changed to ferromagnetic (TC =150-750 K) at higher fields, suggesting metamagnetic behavior for all samples. As predicted, Hf2 FeRu3 Ir2 B2 has the highest intrinsic coercivity (Hc =74 kA/m) reported to date for Ti3 Co5 B2 -type phases. Furthermore, all coercivities outperform that of ferromagnetic Hf2 FeIr5 B2 , indicating the importance of AFM interactions in enhancing magnetic anisotropy in these materials. Importantly, two members (x=1 and 4) maintain intrinsic coercivities in the semi-hard range at room temperature. This study opens an avenue for controlling magnetic hardness by modulating antagonistic AFM and FM interactions in low-dimensional rare-earth-free magnetic materials.

Preparation and control mechanism of anisotropic Sm-Pr-Co/Co nanocomposites with unusual continuous soft-phase coatings

To produce nanocomposite materials with high magnetic properties, studies concerning nanostructural processing technologies and control mechanisms are urgently required in aspects of achieving perfect alignment of the hard phase while keeping desired sizes and distributions of the soft phase. In the present study, a designed low-rate electroless deposition method is found to be an effective way in producing strong textured anisotropic Sm-Pr-Co/Co nanocomposites with unusual continuous soft-phase coatings when assembling Co particles on the ball-milled anisotropic Sm-Pr-Co hard phase. The average particle size of the soft-phase coatings is 18–50 nm and the obtained Sm-Pr-Co/Co composites exhibit a high intrinsic coercivity of Hci = 748 kA/m with an enhanced remanence of Mr = 79 A·m2/g, as compared to Hci = 836 kA/m and Mr = 68 A·m2/kg for uncoated Sm-Pr-Co hard phase. Moreover, the coating process study reveals a nucleation control mechanism for the formation of the continuous coating structures. Down-sized Sm-Pr-Co/Co nanocomposites with tailored size below 300 nm or even below 100 nm were also produced by this designed method. This study is of theoretical and practical importance for developing advanced nanostructures including the next generation permanent magnets.

Nanostructured multicomponent Nd-Fe-B magnets prepared by a spark-plasma-sintering approach

The magnetic properties of an Nd-Fe-B-type permanent magnet depend on the microstructure and the chemistry of the material. To compensate for unfavorable microstructural features, such as micron-sized grains of the hard-magnetic phase, the intrinsic coercivity is often enhanced by the addition of heavy-rare-earth elements, but these additions also reduce the magnetization. In some applications, like electro-mechanical devices, a high intrinsic coercivity is only required in certain regions of a magnet. In such cases, using magnets with locally tailored magnetic properties, i.e., multicomponent magnets, would enhance the magnet-containing device’s performance. Here, we propose a spark-plasma-sintering (SPS) approach to the manufacture of multicomponent Nd-Fe-B magnets. By exploiting the SPS-specific processing conditions, namely fast heating rates (100 °C/min) and low consolidation temperatures (≈670 °C), such magnets can be prepared directly from nanostructured melt-spun powders (the one-step SPS approach) or SPS-processed precursor magnets (the two-step SPS approach). Optimizing the SPS processing conditions prevents the grain coarsening related to the pre-existing microstructural inhomogeneities of the powders. The magnetic characterization reveals reliable performance over a wide range of operating temperatures. The high remanent magnetization of a heavy-rare-earth-free powder (Br = 0.82 T) and the high intrinsic coercivity of a powder containing 1.5 at. % Dy (Hci = 2075 kA/m) are preserved in a multicomponent magnet characterized by an abrupt change in magnetic properties close to the interface between the respective magnet parts.

Improvement in magnetic properties, corrosion resistance and microstructure of Nd–Fe–B sintered magnets through intergranular addition of Tb68Ni32

New energy vehicles and offshore wind power industries have a high demand for sintered Nd–Fe–B magnets with high intrinsic coercivity and high corrosion resistance. In this study, the magnetic properties, anticorrosion properties, and microstructure of Nd–Fe–B sintered magnets with the intergranular addition of low-melting-point eutectic Tb68Ni32 alloy powders were investigated. The aim is to determine if the addition of Tb68Ni32 can improve these properties. A low melting-point eutectic alloy Tb68Ni32 powders was prepared as a grain boundary additive and blended with the master alloy powders prior to sintering. The coercivity of the resultant magnets gradually increases from 1468 to 2151 kA/m by adding increasing amounts of Tb68Ni32. At the same time, the remanence first increases and then slightly decreases. After studying the microstructure and elemental composition of the Tb68Ni32 added magnets, it is found that the significant increase in coercivity and the negligible reduction in remanence is due to densification, improved grain orientation, a uniform and continuous boundary phase distribution, as well as the generation of a (Nd,Pr,Tb)2Fe14B “core–shell” structure surrounding the main-phase grain. Moreover, the corrosion resistance of the magnet is greatly improved owing to the enhancement of electrochemical stability, as well as the optimization of the distribution and morphology of the intergranular phase.

Identification of optimal solid solution temperature for Sm2Co17-type permanent magnets with different Fe contents

It is confirmed that the solid solution temperature range to obtain optimal magnetic properties is different for the magnets with different Fe contents, and the correlation between magnetic properties and microstructures influenced by solid solution temperature (Ts) has been systematically studied. The optimal solid solution temperature range is 1413–1463 K for the Sm(CobalFe0.213 Cu0.073Zr0.024)7.6 magnet, which is higher than that of the Sm(CobalFe0.262Cu0.073Zr0.024)7.6 magnet (1403–1453 K), and the optimal Ts range is about 50 K for both of the magnets. The solid solution temperature range shifting toward relatively high temperature is due to the increase in a phase transition temperature. The magnet solution-treated at proper temperature exhibits 1:7H single phase, and intact cell structure and high Cu concentration (23.12 at%) in the cell boundary are found after aging process, which makes the magnet shows high intrinsic coercivity (Hcj) and magnetic field at knee-point (Hknee). At a lower solid solution temperature, the 2:17H, 1:5H and Zr-rich precipitation phases appear, which affects the cell structure, density of lamellar phase and Cu concentration in the cell boundary, leading to the reduced magnetic properties. However, at a higher solid solution temperature, there exist obviously light gray and dark regions with different Sm, Cu and Fe contents in scanning electron microscopy observation, and the magnet shows low pinning field in the two regions and incomplete cell structure, resulting in an inferior Hcj and Hknee.

An exploration of nanocomposite Nd-Fe-B/Alnico alloys with enhanced intergrain interactions and improved magnetic properties

Nd-Fe-B alloys have high intrinsic coercivity, high magnetic energy density, but low Curie temperature and poor temperature stability. While Alnico alloys have high Curie temperature and high temperature stability, but low intrinsic coercivity and low magnetic energy density. It would be of great scientific, technological and economical interest if these two alloys could be combined together in some proportion to make composite magnets with good comprehensive properties. Here we report nanocrystalline composite magnets containing Nd-Fe-B hard phase and alnico semi-hard phase fabricated by melt-spinning technique. A novel core-shell like structure constituting Nd-Fe-B (2:14:1) phase as core and Alnico rich phase as shell was obtained by optimizing the composition and processing conditions. The maximum energy density was enhanced upto 150 kJ/m3 in nanocomposite magnets. The Curie temperature of the main phase increased to 654 K for Nd-Fe-B/Alnico from 581 K for pure Nd-Fe-B alloy, which is attributed to the molecular field penetration of Alnico phase into the hard 2:14:1 phase, in addition to the substitution of Fe by Co and Ni. No kink or dip was observed in the demagnetization curves, which suggested the presence of strong exchange interactions among the phases of the nanocomposite alloys.

Dependence of macromagnetic properties on the microstructure in high-performance Sm2Co17-type permanent magnets

Microstructure characteristics are important for the high-performance Sm2Co17-type permanent magnets to achieve high intrinsic coercivity (Hcj) and large magnetic field at the knee-point (Hknee). In this work, the correlation between microstructures and magnetic properties has been systematically studied. The different microstructures were obtained by two procedures: by adjusting the aging temperature and optimizing the Zr content. On one hand, with increase of aging temperature from 1063 K to 1103 K, the cell size and the lamellar phase density increase from 75.1 nm and 0.014 1/nm to 101.5 nm and 0.043 1/nm, respectively, and the average peak Cu concentration at the cell boundaries reaches 21.9 at% which is helpful for obtaining relatively high Hcj and Hknee. As the aging temperature increases further to 1143 K, a much larger cell size and with incomplete cell boundaries results in an irregular distribution of Cu concentration at the cell boundaries. In this case, the Hknee is low even though the magnet shows a high Hcj. On the other hand, the increase of Zr content also promotes an increase in both the lamellar phase density and the average peak Cu concentration at the cell boundaries, giving rise to high Hcj and Hknee. Taking into consideration the aging temperature and Zr content, one can conclude that a lower aging temperature and lower Zr content produce a lower lamellar phase density and average Cu concentration at the cell boundaries and this leads to a lower Hcj and Hknee of the magnets. To further confirm this correlation between the microstructures and magnetic properties, a magnet of Sm(CobalCu0.062Fe0.285Zr0.016)7.6 was aged at a higher temperature of 1143 K to increase the lamellar phase density. As expected, the lamellar phase density increases from 0.008 to 0.013 1/nm; however, the cell size increases simultaneously from 142.5 to 247 nm. The magnet exhibits a much higher but uneven Cu concentration at the cell boundaries. As a result, the Hcj increases from 1.64 to 10.18 kOe, while Hknee just increases from 1.09 to 3.91 kOe.

Antisymmetric linear magnetoresistance and the planar Hall effect

The phenomena of antisymmetric magnetoresistance and the planar Hall effect are deeply entwined with ferromagnetism. The intrinsic magnetization of the ordered state permits these unusual and rarely observed manifestations of Onsager’s theorem when time reversal symmetry is broken at zero applied field. Here we study two classes of ferromagnetic materials, rare-earth magnets with high intrinsic coercivity and antiferromagnetic pyrochlores with strongly-pinned ferromagnetic domain walls, which both exhibit antisymmetric magnetoresistive behavior. By mapping out the peculiar angular variation of the antisymmetric galvanomagnetic response with respect to the relative alignments of the magnetization, magnetic field, and electrical current, we experimentally distinguish two distinct underlying microscopic mechanisms: namely, spin-dependent scattering of a Zeeman-shifted Fermi surface and anomalous electron velocities. Our work demonstrates that the anomalous electron velocity physics typically associated with the anomalous Hall effect is prevalent beyond the ρxy(Hz) channel, and should be understood as a part of the general galvanomagnetic behavior.

Quantifying the nucleation effect of correlated matrix grains in sintered Nd-Fe-B permanent magnets

The long-standing issue-the ferromagnetic coupling of adjacent Nd2Fe14B matrix grains across grain boundaries severely impedes further coercivity enhancement of sintered Nd-Fe-B permanent magnets. However, the quantitative role of the ferromagnetic coupling across grain boundaries on the coercivity degradation of sintered Nd-Fe-B magnets is still not well understood. Here, we quantified the nucleation effect of correlated (ferromagnetically coupled) matrix grains in sintered Nd-Fe-B magnets by integrating electron backscatter diffraction, energy dispersive spectroscopy, atom probe tomography, and high-resolution magnetic force microscopy in conjunction with micromagnetic simulations. We revealed that (1) the de-nucleation effect of correlated matrix grains (αψ) across intergranular grain boundaries is linearly enhanced with the increasing thickness (d) of grain boundaries (αψ = kd + l) and k is reduced with increasing exchange stiffness of these grain boundaries when the d is comparable to the domain wall width of the Nd2Fe14B matrix grains in sintered Nd-Fe-B magnets; (2) The thickness variation of the ferromagnetic grain boundary at the nanoscale is harmful to achieving high intrinsic coercivity of sintered Nd-Fe-B magnets; (3) The nucleation field is reduced if there is a little misalignment between correlated (ferromagnetically coupled) matrix grains. These findings shed light on grain boundary engineering at the nanoscale for enhancing the coercivity of Nd-Fe-B permanent magnets.

Studies on preparation and properties of low temperature phase of MnBi prepared by electrodeposition

MnBi alloy with low-temperature phase (LTP) is a promising candidate as rare-earth-free permanent magnet for its high intrinsic coercivity and the unique positive temperature coefficient. Many works have investigated on the preparation of the LTP-MnBi using physical methods, while there are few reports about the successful fabrication using electrodeposition method although this low cost process has been used for many material preparations so far. The main difficulty is the large negative reduction potential of manganese ions and on the basis the big difference between the reduction potentials of manganese ions and bismuth ions. In this paper, we reduced the reduction potentials of manganese ions and bismuth ions firstly and on this basis, the MnBi films with different ratios of manganese and bismuth were prepared using different deposited potentials. After annealed treatment of 380 °C, there appears the low temperature phase in XRD pattern for the sample in which the ratio of manganese and bismuth is 54:46. This is the first report in electrodeposited method so far and the corresponding coercivity reaches 1450 Oe measured by the physical property measurement system (PPMS).

Origin of the Intrinsic Coercivity Field Variations of ε-Fe2O3

e-Fe2O3 phase is recognized as an attractive material, in both technological and scientific point of view, since it can achieve very high room-temperature coercivity (10–20 kOe). In this paper, multi-phase samples Fe2O3/SiO2 with slightly different $${\text{Fe/Si}}~$$ molar ratio were produced by sol–gel synthesis route. The obtained samples were characterized by various experimental techniques including XRD, TA, FTIR, and $${\text{SQUID}}$$ (DC and AC magnetic measurements). It was found that both samples consisted of α-Fe2O3 and e‑Fe2O3 phases embedded in the silica matrix, and showed very similar structural and magnetic properties, except that displayed significantly different room-temperature intrinsic coercivity field values: HciS1 = 14.3 kOe and HciS2 = 7.5 kOe. We have discussed possible origin of thus high intrinsic coercivity field variation.

Influence of Alloying Elements Zr, Nb and Mo on the Microstructure and Magnetic Properties of Sintered Pr-Fe-Co-B Based Permanent Magnets

The addition of alloying elements on rare-earth permanent magnets is one of the methods used to improve the magnetic properties. This present work evaluates the influence of alloying elements such as Zr, Nb and Mo on the microstructure and magnetic properties of sintered Pr-FeCo-B based permanent magnets. The permanent magnets were produced by the conventional powder metallurgy route using powder obtained by hydrogen-decrepitation (HD) method from as cast alloys. In order to produce the magnet Pr16Fe66,9Co10,7B5,7Cu0,7 without alloying elements the mixture of alloys method was employed, mixing two compositions: Pr20Fe73B5Cu2 (33% w.t) and Pr14Fe64Co16B6 (67% w.t). With the purpose of evaluating the influence of the alloying elements, the Pr14Fe64Co16B6X0,1 (where X= Zr, Nb or Mo) (67% w.t) alloy was employed. The characterization of the alloys and the magnets was carried out using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDXS) and the magnetic properties were measured using a permeameter. The magnet without any additions presented the highest intrinsic coercivity (μ0iHc = 748 KA.m-1) while the magnet with Nb addition presented higher remanence (Br = 1,04 T). The magnet with Zr addition presented the highest maximum energy product (BHmáx = 144 KJ.m-3), and the magnet with Mo addition showed the highest squareness factor (SF = 0,73).

The role of cobalt addition in magnetic and mechanical properties of high intrinsic coercivity Nd-Fe-B magnets

The role of cobalt addition in magnetic and mechanical properties of high intrinsic coercivity Nd-Fe-B magnets by adding cobalt element and blending micron cobalt powder was investigated. The results showed that the excellent magnetic properties of high intrinsic coercivity Nd-Fe-B magnets were obtained at the Co content of 1.5 wt%, and then the intrinsic coercivity and fracture toughness decline after blending 3 wt% micron Co powder. Blending Co powder increased the Co content of main phase grain and Nd-rich phase, and the phenomenon that the Co powder additive is in the presence of pure Co particles was not been found in the sample. Simultaneously, blending Co powder reduced the heavy rare earth content of main phase grain, and new phases containing heavy rare earth and Co were formed, such as soft ferromagnetic phase R(FeCo)3, the low-anisotropy phase R(FeCo)5 and rich-B phase R1.1(FeCo)4B4. These phenomena lead to a decrease in the intrinsic coercivity of high intrinsic coercivity Nd-Fe-B magnets. Further investigation on the grain and grain boundary indicated that the effect mechanism of blending Co powder on magnetic properties is not the same as that of the traditional alloying route.

The microstructure and magnetic characteristics of Sm(CobalFe0.1Cu0.09Zr0.03)7.24 high temperature permanent magnets

Two kinds of Sm(CobalFe0.1Cu0.09Zr0.03)7.24 high temperature magnets were fabricated by a traditional powder metallurgical technology with different annealing processes. A record of maximum energy product of 94.73kJ/m3 at 773K with a high intrinsic coercivity of 652.72kA/m was made. Based on the theoretical and experimental results, it was found that the temperature coefficient of the coercivity was strongly influenced by the variation of the Curie temperature of the cell wall phases and the domain wall energy ratio between cell and cell wall phases at 0K. The characteristic properties originate from the element redistribution between SmCo5/Sm2Co17 interfaces while annealing.

Inducing magnetic anisotropy and optimized microstructure in rapidly solidified Nd–Fe–B based magnets by thermal gradient, magnetic field and hot deformation

Direct preparation of Nd–Fe–B alloys by rapid solidification of copper mold casting is a very simple and low cost process for mini-magnets, but these magnets are generally magnetically isotropic. In this work, high coercivity Nd24Co20Fe41B11Al4 rods were produced by injection casting. To induce magnetic anisotropy, temperature gradient, assisted magnetic field, and hot deformation (HD) procedures were employed. As-cast samples showed non-uniform microstructure due to the melt convection. The thermal gradient during solidification led to the formation of radially distributed acicular hard magnetic grains, which gives the magnetic anisotropy. The growth of the oriented grains was confirmed by phase field simulation. A magnetic field up to 1 T applied along the casting direction could not induce significant magnetic anisotropy, but it improved the magnetic properties by reducing the non-uniformity and forming a uniform microstructure. The annealed alloys exhibited high intrinsic coercivity but disappeared anisotropy. HD was demonstrated to be a good approach for inducing magnetic anisotropy and enhanced coercivity by deforming and refining the grains. This work provides an alternative approach for preparing fully dense Nd-rich anisotropic bulk Nd–Fe–B magnets.

Influence of dysprosium substitution on magnetic and mechanical properties of high intrinsic coercivity Nd-Fe-B magnets prepared by double-alloy powder mixed method

The double-alloy powder mixed method is very proper for developing new small-mass products by changing the composition of sintered Nd-Fe-B magnets, and there is little research on this aspect. The variation on magnetic and mechanical properties of high intrinsic coercivity Nd-Fe-B magnets prepared by double-alloy powder mixed method was discussed, which is a method blending two-type main phase alloy powders with different components. The results showed that the intrinsic coercivity and density of sintered Nd-Fe-B magnets increased gradually with the increase in Dy content, and the double-alloy powder mixed method could obtain high intrinsic coercivity Nd-Fe-B magnets with good crystallographic alignment and microstructure. The bending strength of sintered Nd-Fe-B magnets declined, and the Rockwell hardness of sintered Nd-Fe-B magnets first declined, and then increased with the increase in Dy content. The microstructure showed that there existed the phenomenon that the Dy element diffused into main phase during sintering process, and the distribution of Dy content in main phase had some variation in homogeneity as a result of incomplete reaction between the double-alloy powder types.

Effect of ball milling and heat treatment process on MnBi powders magnetic properties

The metallic compound MnBi has high intrinsic coercivity with large positive temperature coefficient. The coercivity of MnBi exceeds 12 kOe and 26 kOe at 300 K and 523 K, respectively. Hence MnBi is a good candidate for the hard phase in exchange coupled nanocomposite magnets. In order to maximize the loading of the soft phase, the size of the MnBi particle has to be close to 500 nm, the size of single magnetic domain. Low energy milling is the common method to reduce MnBi particle size. However, only 3–7 μm size particle can be achieved without significant decomposition. Here, we report our effort on preparing submicron MnBi powders using traditional powder metallurgy methods. Mn55Bi45 magnetic powders were prepared using arc melting method, followed by a series of thermal-mechanical treatment to improve purity, and finished with low energy ball milling at cryogenic temperature to achieve submicron particle size. The Mn55Bi45 powders were decomposed during ball milling process and recovered during 24 h 290 °C annealing process. With increasing ball-milling time, the saturation magnetization of MnBi decreases, while the coercivity increases. Annealing after ball milling recovers some of the magnetization, indicating the decomposition occurred during the ball-milling process can be reversed. The coercivity of Mn55Bi45 powders are also improved as a result of the heat treatment at 290 °C for 24 h. The world record magnetization 71.2 emu/g measured applying a field of 23 kOe has been achieved via low energy ball mill at room temperature.

Mechanical and electrical properties of low temperature phase MnBi

Low temperature phase (LTP) manganese bismuth (MnBi) is a promising rare-earth-free permanent magnet material due to its high intrinsic coercivity and large positive temperature coefficient. While scientists are making progress on fabricating bulk MnBi magnets, engineers have begun considering MnBi magnets for motor applications. Physical properties other than magnetic ones could significantly affect motor design. Here, we report results of our investigation on the mechanical and electrical properties of bulk LTP MnBi and their temperature dependence. A MnBi ingot was prepared using an arc melting technique and subsequently underwent grinding, sieving, heat treatment, and cryomilling. The resultant powders with a particle size of ∼5 μm were magnetically aligned, cold pressed, and sintered at a predefined temperature. Micro-hardness testing was performed on a part of original ingot and we found that the hardness of MnBi was 109 ± 15 HV. The sintered magnets were subjected to compressive testing at different temperatures and it was observed that a sintered MnBi magnet fractured when the compressive stress exceeded 193 MPa at room temperature. Impedance spectra were obtained using electrochemical impedance spectroscopy at various temperatures and we found that the electrical resistance of MnBi at room temperature was about 6.85 μΩ m.