Dispersing high volume fraction of soft magnetic phases with high saturation magnetization (Ms), such as Fe or FeCo, into nanocrystalline rare-earth permanent magnets imparts ultrahigh theoretical maximum energy products ((BH)max). For instance, the Nd2Fe14B/α-Fe nanocomposite magnet containing ~70 vol.% soft phase is theoretically predicted to achieve (BH)max values approaching 100 MGOe, substantially exceeding the theoretical limit of ~64 MGOe for single-phase Nd2Fe14B. However, the experimental realization of this potential in Fe-rich nanocomposites has long been hindered by the intrinsic difficulty of simultaneously achieving strong crystallographic texture in the hard magnetic phase and maintaining nanoscale grain sizes in the soft phase. In this work, we present a synergistic strategy that successfully achieves a strong (00l) preferred orientation of the hard magnetic phase in Pr2Fe14B/α-Fe nanocomposites containing 50 wt. % α-Fe, while maintaining an average grain size of only ~15 nm. As a result, a record-high maximum energy product of 20.7 MGOe is achieved at this high soft-phase content, representing a 2.6-fold enhancement over previously reported values for compositions with comparable soft-phase fractions. Moreover, this approach significantly strengthens interphase exchange coupling. This work overcomes a longstanding challenge in nanocomposite magnet design, namely, inducing strong crystallographic texture in magnets with high soft-phase fractions and nanoscale grain sizes, and provides a viable route for the development of high-performance nanocrystalline composite permanent magnets.

The mechanical properties of Sm2Co17 magnets are improved by introducing oxide powders. However, there is a trade-off between the mechanical and magnetic properties. It is important to explore an oxide powder that effectively improves the mechanical properties while avoiding more introduced nonmagnetic elements. TiO2 is a candidate because it is more reducible than Sm2O3 and Ti in it is in +4 valence state. In this work, a small amount (0.08 wt%-0.38 wt%) of fine TiO2 powers (average powder size is similar to 0.2 mu m) were introduced into the magnets. The fracture mechanism of TiO2-added magnets is still brittle cleavage fracture. With TiO2 addition of 0.08 wt%, the maximum energy product (BH)(max) of the magnet is more than 218 kJ/m(3), and the coercivity H-cj is larger than 2290 kA/m. More impressively, the maximum flexural strength of the magnets is improved by 37% compared to the original magnet. The introduced TiO2 is reduced by Sm in the magnet to form Ti and Sm2O3 at sintering. Ti is uniformly distributed in the matrix. The newly-formed Sm2O3 particles and the ones from the unavoidable oxidation during the preparation process are mainly distributed on the grain boundaries. The particles refine the grains by the Zener pinning effect. Thus, the flexural strength of magnet is improved. Furthermore, with the TiO2 addition up to 0.38 wt%, the mean grain size decreases by about 36.9%. However, the flexural strength is not further improved significantly. The evolution of the flexural strength is expected to be associated with the larger cellular structure sizes and the increased number of Sm2O3 aggregation zones. The results provide a new perspective and inspiration for enhancing the mechanical properties of Sm2Co17-type magnets. (c) 2025 Chinese Society of Rare Earths. Published by Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

Hot extrusion is the key forming technique for the efficient fabrication and broad-scale utilization of integrated hot-deformed Nd-Fe-B ring magnets. However, the extrusion method remarkably affects the formability and macro-micro performances of hot-deformed Nd-Fe-B ring magnet. The forming behavior and macro-micro performance evaluation under different extrusion methods are very important to obtain high-performance and uniform ring magnets. Therefore, in this paper, a complete research chain comprising simulation analysis, magnetic property evaluation, and microstructural characterization was established to delve into the influences of the forward extrusion (FE) and backward extrusion (BE) methods on the forming behavior and macro-micro performances of Nd-Fe-B ring magnets. The results indicate that the BE method induces a larger-angle flow offset and yields a “turbulent region” at the chamfer area due to the “opposite movement” characteristic between the forming and punching directions, which significantly enhances the shear action, resulting in a favorable mechanical condition for adequate deformation. Consequently, the BE ring magnet exhibits a better performance, achieving optimal values of 13.06 kGs for Br and 39.07 MGOe for (BH)max, respectively. In contrast, with the characteristics of small-angle continuous shear rheology, the FE method shows better forming stability, which can significantly reduce the axial gradient and improve performance uniformity. The distributions of macro-micro performances in the ring magnet are relatively uniform, including effective strain, magnetic properties, orientation degree, the interval of adjacent RE-rich lamellas, and the grain morphology and size along the axial direction. The research results of this paper are favorable for revealing the intrinsic correlation mechanism between the forming behavior and performances of Nd-Fe-B material under the FE and BE methods at the micro and macro levels, and delivering a theoretical insight for optimizing hot extrusion methods to fabricate high-performance uniform hot-deformed Nd-Fe-B ring magnets.

Nanocomposite magnets possessing an ultrahigh soft-phase fraction (> 50 wt. %) and ultrafine nanocrystals are promising candidates for achieving enhanced magnetic performance by simultaneously harnessing high saturation magnetization and strong hard–soft exchange coupling. However, bulk ultrahigh soft-phase-fraction nanocomposites often suffer from grain coarsening and soft-phase agglomeration during the prolonged high-temperature processing required for densification, leading to weakened hard–soft exchange coupling and degraded magnetic performance. Here, we report a flash Joule heating (> 104 K/min) combined with high-pressure deformation (FJH-HPD) strategy that enables seconds-scale (~ 7 s) fabrication of bulk fully dense nanocomposite magnets with an ultrahigh soft-phase fraction of approximately 65 wt. %. The obtained magnets feature ultrafine nanograins (~ 27 nm), with soft-phase agglomeration effectively suppressed, and a relative density exceeding 99% of the theoretical value. Benefiting from both the record-high saturation magnetization (17.4 kG) and the strong hard–soft exchange coupling, the isotropic magnet exhibits a high remanence of 14.2 kG, accompanied by a markedly enhanced magnetic energy product of 17.8 MGOe—174% higher than previously reported values at comparable soft-phase fractions. This ultrafast nonequilibrium fabrication strategy develops a promising manufacturing route to prepare bulk nanocomposite magnets containing ultrahigh soft-phase fractions.

The development of a well-defined cellular nanostructure during isothermal aging is essential for realizing high magnetic performance in 2:17-type Sm-Co-Fe-Cu-Zr magnets. However, the microstructure evolution of this nanostructure, particularly in Fe-rich compositions, has remained ambiguous. This study examines the aging response of magnets containing 17.5–21.5 wt% Fe subjected to isothermal treatment at 840 °C for durations spanning 5 to 50 h. A clear Fe-content dependence of the aging kinetics is observed: as Fe content rises from 17.5 to 21.5 wt%, the time necessary to establish a complete cellular morphology and corresponding peak magnetic properties increases from 10 h to 40 h. The origin of this retardation lies in the solid-solution precursor state. Higher Fe concentrations promote the formation of pre-existing 2:17R nano-twin microdomains at the expense of the metastable 1:7H matrix. Unlike the 1:7H phase which readily generates abundant basal stacking faults that serve as fast diffusion channels, these pre-ordered 2:17R regions resist further defect generation and reduce the chemical driving force for Cu redistribution. Consequently, elemental partitioning of Cu, Fe, and Zr is delayed, prolonging the necessary aging time. Clarification of this precursor-dependent evolution provides a rational basis for tailoring aging protocols to achieve enhanced magnetic performance in Fe-rich SmCo magnets.

This study systematically investigates the influence of PrAlCu alloy co-diffusion with TbHx on the magnetic properties and microstructure of sintered NdFeB magnets. Through the synergistic diffusion of PrAlCu and TbHx, the coercivity of the magnet was enhanced from 13.52kOe to 25.75kOe. Microstructural and compositional analyses revealed that the preferential diffusion of PrAlCu facilitates the formation of a more homogeneous grain boundary (GB) phase distribution, which creates low-melting-point diffusion channels and thereby improves the subsequent diffusion efficiency and penetration depth of Tb. In contrast, the initial magnet exhibits an indistinct GB phase distribution, leading to direct contact between some main phase grains. Under such conditions, direct Tb diffusion produced incomplete "semi-core-shell" structure due to the absence of diffusion pathways. Micromagnetic simulations further elucidate the distinct effects of complete and "semi-core-shell" structures on magnetic properties. The results confirm that continuous and complete core-shell structures more effectively enhance coercivity by suppressing domain nucleation and restricting magnetization reversal.

The evolution of microstructure and magnetic properties of the Ce-based magnet after grain-boundary diffusion (GBD) was investigated. In this work, a Dy35Fe65 alloy (the ratio of Dy: Fe being close to 1: 2) was used as the diffusion source, the (Ce, Nd)-Fe-B sintered magnet with over 30% Ce substitution was used as the starting material. It was found that Dy35Fe65 diffusion effectively enhanced the coercivity of the Ce-based magnet. The optimal magnetic properties were achieved in the magnet diffused at 880 degrees C. The coercivity increased from 11.09 kOe to 14.29 kOe, at the same time, the remanence (Br) slightly increased from 13.06 kG to 13.10 kG, and the maximum energy product ((BH)max) obviously increased from 39.91 MGOe to 41.12 MGOe, after diffusing Dy35Fe65 under the optimal diffusion process.The coercivity of Dy35Fe65 diffused Ce-based magnet was comparable to that of the corresponding Dy diffused magnet. It is noteworthy that Dy35Fe65 GBD not only enhanced Hcj,but also increased the Br and (BH)max. Dy-rich (RE, Dy)2Fe,4B shells have formed in the outer of the main-phase grains of the Ce-based magnet diffused with Dy35Fe65. It seems the formation mechanism of (RE, Dy)2Fe,4B shells abide by the dissolution-solidification mechanism.

Grain boundary diffusion (GBD) is commonly used to improve the performance of sintered Nd-Fe-B magnet. This process enables the formation of heavy-rare-earth-rich shell on main phase grain, the higher anisotropy field of which is considered to contribute to the enhanced coercivity. However, the mechanism of coercivity strengthening remains unclear. In this study, a self-developed in-situ magnetizing holder was employed in Lorentz transmission electron microcopy to observe the evolution of magnetic domain during the magnetization process of core-shell structured grains. The results show that during demagnetization, the grains maintain single domain structure and undergo magnetization reversal sequentially, the core and shell parts of each grain reverse at the same time, revealing strong exchange coupling between the two regions and magnetic decoupling by the grain boundary. Micromagnetic simulations corroborate the experimental observations. This work provides direct experimental evidence to elucidate the macro property and magnetic hardening mechanism of GBD sintered NdFe-B magnet.

Achieving multistep magnetization switching in two-dimensional (2D) ferrimagnets demonstrates substantial promise for advancing high-density non-Boolean logic and memory devices. However, existing 2D ferrimagnets are still hampered by low Curie temperatures and a lack of tunable multiple magnetic states. Here, we report the successful synthesis of a family of 2D Fe0.875S(1-x)Sex alloy with robust room-temperature ferrimagnetism. The key magnetic and electrical properties can be effectively regulated by tailoring the chalcogen ratio in Fe0.875S(1-x)Sex alloy. Notably, multiple magnetic states and resistance plateaus are observed because of the spin canting behavior, enabling the realization of several distinct spin states by adjusting magnetic fields and temperatures, thereby demonstrating great potential for multistate applications. Density functional theory calculations further reveal that the evolution of magnetic anisotropy originates from variations in the orbital occupation of electronic states near the Fermi level. Our work can expand the library of 2D metallic ferrimagnets and pave the way for designing high-density spintronic devices.

TEM observations of the same Nd-Fe-B foil before and after oxidation at 350 degrees C reveal that the oxidation process involves the precipitation of alpha-Fe from the main phase, followed by its outward diffusion and oxidation. Suppressing this process could provide a new pathway to enhance the corrosion resistance of the main phase. Accordingly, a strategy of introducing a corrosion-resistant element (Cr) into the main phase to strengthen the corrosion resistance of Nd-Fe-B magnets is proposed. Cr preferentially reacts with oxygen to form a Cr2O3 layer, which suppresses the formation of loose Fe2O3 on the surface and retards oxygen ingress, thereby effectively protecting the main phase. The polarization curve results demonstrate that regulating the main phase through Cr incorporation leads to a two-order-of-magnitude reduction in the corrosion current of Nd-Fe-B magnets, a level of improvement unattainable through grain boundary phase modification. Tuning the main phase, rather than solely focusing on the grain boundary phase, enables a continuous enhancement of corrosion resistance, underscoring the critical role of the main phase. Magnet with synchronous regulation of both the grain boundary phase and the main phase achieves a balanced performance in both corrosion resistance and magnetic properties. This work not only deepens the theoretical understanding of corrosion resistance in Nd-Fe-B magnets but also provides valuable insights for achieving breakthrough improvements in their long-term durability.

Different annealing heat treatment processes were performed on Ni-Si hypereutectic composites at the solidification rate of 40 µm/s to eliminate the metastable phase and the best heat treatment process was selected (annealing temperature 1 000 °C, holding time 4 h). The oxidation weight gain and oxide rate, oxide film morphology, and oxidation kinetics of Ni-Si hypereutectic composites were studied. Moreover, the formation mechanism of the oxide film was investigated through a thermodynamic analysis, specifically by calculating the change of Gibbs free energy associated with the oxidation reactions. It is found that the oxide resistance of the Ni-Si hypereutectic composite without metastable phase is better than that of the 67.9

O3-type layered oxides show promise for sodium-ion batteries with high capacity and affordability, yet suffer from oxygen evolution and structural instability at high voltage, impairing cycling performance. To address these challenges, Se surface treatment was employed to construct Na2SeO4 coating/surface Se doping on the O3-type layered oxides surface, suppressing lattice oxygen evolution and internal stress accumulation. On one hand, the high-valence Se⁶⁺ in Na₂SeO₄ withdraws electrons, creating a depletion region and built-in electric field at the surface. This field drives bulk electrons to the interface, reducing TMO-slab electron density, weakening interlayer repulsion, and thereby mitigating internal stress accumulation. On the other hand, surface Se doping substitutes for surface oxygen vacancies, forming O-TM-Se configurations, transplanting the pumped charges from Oα−, reducing them to immobile O2− and stabilizing the lattice oxygen during high-voltage cycling process. As anticipated, the modified NFMS material exhibits outstanding electrochemical stability. Within 2.0–4.0 V, it retains 70.4 % capacity retention after 1300 cycles at 5 C, and even at 4.3 V, maintains 70 % after 500 cycles. In practical applications, pouch-type full cells show 75.3 % retention at 0.5 C over 1100 cycles at 1.5–4.0 V. This innovative strategy offers a new approach to suppressing oxygen evolution by manipulating the surface chemistry of O3-type cathode materials.

Al-Nd alloys are crucial sputtering target materials for suppressing hillock formation in Al thin films within display devices. To optimize the hot processing parameters and elucidate the microstructure evolution mechanisms of Al-2.5 at.%Nd alloy, hot compression tests were conducted using a Gleeble-3800 thermal simulator over a temperature range of 300-450 degrees C and strain rates of 0.001-1 s(-1). An Arrhenius-type constitutive model incorporating the Zener-Hollomon parameter (Z) was established, demonstrating high correlation (R-2 = 0.977) and low prediction error (AARE = 6.61%), enabling accurate flow stress prediction. Processing maps based on the Dynamic Materials Model identified two optimal processing windows: 0.001-0.008 s(-1)/360-430 degrees C and 0.003-0.05 s(-1)/430-450 degrees C. Quantitative modeling of dynamic recrystallization (DRX) kinetics using the Yada model revealed that the DRX volume fraction increased with decreasing strain rate and increasing deformation temperature. Electron backscatter diffraction and transmission electron microscopy characterizations and analyses confirmed that lower strain rates reduced dislocation density and promoted DRX nucleation and growth. This study reveals the influence of (AlNd3)-Nd-11 phase on the high deformation activation energy, DRX behavior and processing instability (such as microcracks) of the alloy, which provides an important theoretical basis and data guidance for the optimization of hot working process of Al-Nd alloy target.

Sintered Nd-Fe-B magnets with low-B and high-Ga content exhibit higher coercivity than conventional magnets, owing to their flat and smooth grain boundary phase and the relatively low Fe content therein. However, after grain boundary diffusion treatment, their coercivity enhancement is significantly smaller than that of traditional Nd-Fe-B magnets, limiting their application in high-performance scenarios. In this study, sintered Nd-Fe-B magnets with low-B and high-Ga content were used as the base material to systematically compare the effects of TbPr and TbPrFe diffusion sources on microstructure and magnetic properties. Results show that TbPr diffusion induces abundant curved grain boundary phase and asymmetric shell structure near the magnet surface, suppressing coercivity improvement and causing a pronounced drop in remanence. In contrast, TbPrFe diffusion effectively suppresses the formation of such asymmetric shell and curved grain boundary phase. Consequently, the coercivity increases markedly by 50.2%, while the reduction in remanence is minimized to only 0.36%. Furthermore, the correlation between microstructural evolution during diffusion and magnetic properties was thoroughly investigated. These findings provide valuable experimental insights for developing high-performance grain boundary diffused sintered Nd-Fe-B magnets with low-B and high-Ga content.

The temperature employed during isothermal aging plays a critical role in the formation of the cellular nanostructure in 2:17-type SmCo magnets. However, current understanding of the effect of aging temperature on the microstructure and corresponding magnetic properties has been largely confined to the range of 800-850 degrees C. In the present work, the aging temperature of 840-950 degrees C was employed on the magnet with an Fe content of 19.5 wt% during the isothermal aging process. The influence of aging temperature on the evolution of the cellular nanostructure was investigated in detail. The results indicate that coercivity increases from 19.3 kOe to 28.4 kOe as the aging temperature rises from 840 degrees C to 930 degrees C, but then decreases markedly to 14.9 kOe at 950 degrees C. The sample aged at 890 degrees C demonstrated the best overall magnetic performance, i.e. (BH)(max)+H-cj similar to 56.7. Additionally, its cellular structure has been optimized, becoming uniform and complete. It was found that samples treated at conventional aging temperatures exhibited a substantial amount of the intermediate phase (2:17 R'), accompanied by inhomogeneous and incomplete cellular structures. These imperfections led to inadequate formation of pinning sites at cell boundaries and junctions. In contrast, the 2:17 R' intermediate phase was effectively suppressed in the magnet aged at 890 degrees C, resulting in a more uniform and well-defined cellular morphology and thereby a significant enhancement in coercivity. The mechanism of magnetic domain wall pinning was systematically elucidated. This study provides valuable insights for the development of advanced SmCo magnets.

High magnetic performance magnets were prepared by applying grain boundary diffusion process (GBDP) using Pr-Tb-Co-Ga alloys. The coercivity is significantly increased from original 1236.2-2121.3 kA/m by diffusing Pr60Tb10Co15Ga15 alloys. The coercivity is increased by 885.2 kA/m while the remanence decreases only 0.013 T. Furthermore, an excellent temperature stability of coercivity is found at elevated temperate, obtaining coercivity of 817.5 kA/m at 423 K. Obvious Tb-rich shells extend to a depth of 800 mm in the Pr60Tb10Co15Ga15 GBDP magnet. It is found that the Tb diffusion coefficient along grain boundary in the Pr60Tb10Co15Ga15 GBDP magnet (2.46 +/- 0.52) x 10-8 cm2/s) at 1198 K is the largest among the GBDP magnets studied. The joint use of Co/Ga is beneficial to improvement of the fluidity and wettability of the grain boundary, giving rise to high Tb diffusion efficiency. The results offer guidance for developing magnets with excellent integrated magnetic properties and low heavy rare earth content (0.35 wt%). (c) 2025 Chinese Society of Rare Earths. Published by Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

Permanent magnetic materials face an inherent remanence (Br)-coercivity (Hc) mutual restriction. The inherent mutual restriction limits the performance of permanent magnets. In this work, lamellar heterostructured NdFeB/ (SmCo + FeCo) nanocomposite magnets with oriented texture were synthesized via a two-step high-pressure thermal compression constrained deformation technique. The magnets achieve a remanence of 13.0 kG (1.3 T), a coercivity of 5.9 kOe (4.7 & times; 105 A/m), and a maximum energy product of 31.6 MGOe (251 kJ/m3). The lamellar heterostructure optimizes the spatial distribution and crystallographic alignment of magnetic phases and enhances exchange coupling between grains. As a result, the mutual restriction between remanence and coercivity is effectively overcome, together with good thermal stability. This study clarifies the structural regulation mechanism of magnetic interactions and provides a viable strategy for developing high-performance nano-composite permanent magnets.

Defects playing a pivotal role on the evolution of cellular structure for Sm2Co17-type magnets, a complex phase alloy system. However, the defects modulation mechanism remains unclear, especially given the complex phase constitution. Herein, a facile strategy to modulate the 1:7 H phase fraction is employed, leading to a substantial enhancement of the maximum energy product from 29.32 to 34.08 MGOe in Fe-rich Sm2Co17-type magnets. Microstructure characterization and structural analysis reveal that the improvement stems from the promoted "2:17 R -> 1:7H" phase transformation during solution treatment. In the magnet with a higher fraction of 1:7 H phase, the continuous precipitation of cell boundary phase was encouraged by the increased density of defects-aggregated cell boundaries. Furthermore, Cu enrichment within the lamellar phase was effectively restrained, resulting in the greatly boosted magnetic properties. The effectively defects modulation obtained from the solid solution phase transformation offers insight in developing high-performance Sm2Co17-type magnets for industrialization.

The design of permanent magnets is typically tailored to exhibit specific characteristics according to diverse application scenarios, such as high corrosion resistance and superior thermal stability. This study developed a multifunctional Nd-Fe-B magnet through grain boundary diffusion with a low-melting-point TbMg alloy. The most remarkable performance enhancement was manifested in its low thermal expansion coefficient. Thermal expansion behavior analysis revealed that the expanded coefficient of the diffused magnets was significantly reduced. A binary TbMg low-melting-point alloy diffusion source was innovatively designed, and microstructural investigations demonstrated that Mg incorporation effectively suppresses the formation of surface anti core-shell structures during the diffusion process, achieving an extraordinary coercivity enhancement of 10.17 kOe. Beyond magnetic performance improvements, electrochemical experiments confirmed substantial corrosion resistance enhancement in the modified magnets. Consequently, the developed magnet simultaneously integrates three critical advantages: reduced thermal expansion coefficient, elevated coercivity, and enhanced corrosion resistance. This breakthrough would address the stringent performance requirements for rare-earth permanent magnets in specialized applications such as humanoid robotics and industrial sensors, where multi-property optimization is essential for operational reliability under complex environmental conditions.