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Irreversible demagnetization processes in high-performance Fe-Nd-B magnets were investigated using a novel test rig. Designed to capture local magnetic field distributions and integral average magnetization in situ, the rig operates under field and temperature conditions similar to those found in electric motors. Validation against established techniques such as the hysteresisgraph and Hall mapper confirmed its accuracy. Furthermore, we observed the ability to detect even small variations of less than 2.5% in coercive field strength across the sample volume using field scans. The system significantly reduces measurement times from days to hours, enabling efficient in situ detection of magnetic field distributions during the whole demagnetization process. [ABSTRACT FROM AUTHOR]

For permanent magnetic materials, anisotropic microstructures are crucial for maximizing remanence Jr and maximum energy product (BH)max. This also applies to additive manufacturing processes such as laser powder bed fusion (PBF-LB). In PBF-LB processing, the solidification behavior is determined by the crystal structure of the material, the substrate, and the melt-pool morphology, resulting from the laser power PL and scanning speed vs. To study the impact of these parameters on the textured growth of grains in the melt-pool, experiments were conducted using single laser tracks on (CoCuFeZr)17Sm2 sintered magnets. A method was developed to quantify this grain shape anisotropy from electron backscatter diffraction (EBSD) analysis. For all grains in the melt-pool, the grain shape aspect ratio (GSAR) is calculated to distinguish columnar (GSAR < 0.5) and equiaxed (GSAR > 0.5) grains. For columnar grains, the grain shape orientation (GSO) is determined. The GSO represents the preferred growth direction of each grain. This method can also be used to reconstruct the temperature gradients present during solidification in the melt-pool. A dependence of the melt-pool aspect ratio (depth/width) on energy input was observed, where increasing energy input (increasing PL, decreasing vs) led to higher aspect ratios. For aspect ratios around 0.3, an optimum for directional columnar growth (93% area fraction) with predominantly vertical growth direction (mean angular deviation of 23.1° from vertical) was observed. The resulting crystallographic orientation is beyond the scope of this publication and will be investigated in future work. [ABSTRACT FROM AUTHOR]

14:2:1 phases enable permanent magnets with excellent magnetic properties. From an application viewpoint, saturation polarization, Curie temperature, and anisotropy constant are important parameters for the magnetic 14:2:1 phases. Novel chemical compositions that represent new 14:2:1 phases require especially maximum saturation magnetization values at application-specific operating temperatures to provide maximum values for the remanence and the maximum energy density in permanent magnets. Therefore, accurate knowledge of the saturation magnetization Ms is important. Ms gets affected by chemical composition in a twofold way, with chemical composition significantly influencing both magnetic moments and crystal structure parameters. Therefore, for magnetic 14:2:1 phases, we have developed a regression model with the aim to predict the saturation magnetization in [µB/f.u.] at room temperature directly from the chemical composition as input features. The dataset for the training and testing of the model is very diverse, with literature data of 143 unique phases and 55 entries of repeated phases belonging to the ternary, quaternary, quinary, and senary alloy systems. Substitutionally dissolved elements are heavy and light rare earth elements, transition metals, and additional elements. The trained model is a voting regressor model with different weights assigned to four base regressors and has generalized well, resulting in a low mean absolute error of 0.8 [µB/f.u.] on the unseen test set of 52 phases. This paper could serve as the basis for developing novel magnetic 14:2:1 phases from chemical composition. [ABSTRACT FROM AUTHOR]

Exchange-coupled [L1.sub.0]-FePt/Fe composite systems with out-of-plane anisotropy are produced to study the influence of the soft magnetic layer thickness and of the character of the interface between hard magnetic [L1.sub.0]-FePt and soft magnetic Fe on the magnetic properties. By the soft magnetic layer thickness [d.sub.Fe] the coercivity can be tailored according to a 1/[d.sup.2.sub.Fe] relation. By depositing part of the Fe layer at elevated temperatures a graded interface between the [L1.sub.0]-FePt layer and the Fe layer is formed which allows an additional fine tuning of the coercivity. This behavior is confirmed by micromagnetic numerical simulations. The simulations furthermore show that the reversal behavior and the thermal stability are nearly the same for out-of-plane and in-plane anisotropy of [L1.sub.0]-FePt. If the remanent magnetization configuration shows deviations from the homogeneous magnetization distribution an alternative low-field thermal reversal mode occurs. Index Terms--Exchange-coupled composite media, FePt, micromagnetism, perpendicular magnetic recording.

Recent achievements in magnetic transmission soft X-ray microscopy are reviewed. The magnetic contrast is given by X-ray magnetic circular dichroism, i.e., the dependence of the absorption coefficient of circularly polarized X-rays on the projection of the magnetization in a ferromagnetic system onto the photon propagation direction. A lateral resolution down at 25 nm is provided by Fresnel zone plates used as optical elements. Recording the images in varying external magnetic fields, inherent chemical specificity, a high sensitivity to thin magnetic layers due to the large contrast, and the possibility to distinguish between in-plane and out-of plane contributions allows detailed studies of magnetization reversal processes in magnetic patterned elements and thin films. Micromagnetic simulations support the experimental findings. The potential to study spin dynamics will be briefly outlined. Index Terms--Magnetic domains, magnetic multilayered films, magnetization reversal, X-ray imaging.

Lab‐scale additive manufacturing of (CoCuFeZr)17Sm2‐based powder is carried out to realize CoSm‐printed parts with hard magnetic properties. For manufacturing a special inert gas, process chamber for laser powder bed fusion is used. A three‐step annealing procedure analogous to sintered magnets is applied. This leads to a coercivity of 2.77 T, remanence of 0.78 T, and maximum energy density of 109.4 kJ m−3 for the printed parts. Compared with an isotropic sintered magnet of comparable composition and annealing procedure, the coercivity is of the same order. Due to the texture of the printed parts, the remanence is 24 % larger. [ABSTRACT FROM AUTHOR]

Lab‐scale additive manufacturing of (CoCuFeZr)17Sm2‐based powder is carried out to realize CoSm‐printed parts with hard magnetic properties. For manufacturing a special inert gas, process chamber for laser powder bed fusion is used. A three‐step annealing procedure analogous to sintered magnets is applied. This leads to a coercivity of 2.77 T, remanence of 0.78 T, and maximum energy density of 109.4 kJ m−3 for the printed parts. Compared with an isotropic sintered magnet of comparable composition and annealing procedure, the coercivity is of the same order. Due to the texture of the printed parts, the remanence is 24 % larger. [ABSTRACT FROM AUTHOR]

The energy barrier to be overcome for thermal reversal, the reversal mode and the effective particle volume involved are determined by the saddle points of the energy surface. We investigate the influence of field misorientation, exchange-coupling and magnetostatic interaction for a 2:1 aspect ratio particle discretized into two subunits. Typically, increasing the field angle from 0[degrees] to 45[degrees] enhances the effective volume in both cases by more than 20%. Index Terms--Elongated ferromagnetic particles, field misorientation, thermal reversal.

By high‐throughput screening the known Fe–Si–Zr system, off‐stoichiometric Laves‐type (Fe,Si)2+xZr1−x is identified to be hard magnetic. For example, intrinsic magnetic properties of Js = 0.8 T, K1 = 1.20 ± 0.15 MJ m−3 and TC = 529 K are found for Fe63–Si12–Zr25 by magnetometry. For the experimental conditions used, the solubility range of the ternary Laves compound is larger than previously presented. [ABSTRACT FROM AUTHOR]