Phase Composition Analysis Research Articles

Performance of Various Manufactured Cements: A Comparative Study of Khyber, Saifco Next, TCI MAX, HK, UltraTech, and Ambuja Cements

Cement is a fundamental material in the construction industry, forming the basis for a wide variety of building applications, such as concrete, mortar, and grouting. The performance of cement depends on a variety of factors, including its consistency, setting time, fineness, specific gravity, and its chemical composition, all of which influence the strength, durability, and workability of concrete. In this study, a comparative performance analysis was conducted on six popular manufactured cements: Khyber, Saifco Next, TCI MAX, HK, UltraTech, and Ambuja. These cements were evaluated based on key characterisTCI Maxs such as consistency, setting time, fineness, and specific gravity, employing advanced techniques like Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD) for microstructural and phase composition analysis. The findings provide valuable insights for construction professionals, material engineers, and researchers interested in the selection of cement for specific construction projects.

Effect of mechanical processing on reduction of iron oxides in man-made raw materials

The study considers ways to increase the efficiency of reduction of iron oxides from man-made waste (dust from electric arc furnaces) using mechanochemical activation (MCA), grinding and pressing. The analysis of chemical and phase compositions of the dust samples was carried out, which made it possible to identify their potential for processing. The experiments included a study of the effect of grinding and pressing at pressures up to 300 MPa on the materials’ phase composition, as well as an assessment of the effects of coke addition during MCA. To study the effect of pressing pressure on the reduction processes, briquettes were fired at a temperature of 1200 °C. The results showed that the degree of iron metallization increases with an increase in pressing pressure: concentration of metallic iron reaches 19 % at a pressure of 300 MPa, which is higher compared to 17 % in the initial state without pressing. The novelty of the work lies in optimizing the pressing parameters and demonstrating its effect on the iron reduction process. The proposed conditions make it possible to increase the efficiency of processing man-made waste, which can be used to improve the environmental and economic components of production.

Exploiting the positive effect of REFe2 (RE=rare earth) phase on coercivity in Nd-Ce-Fe-B sintered magnets

The REFe2 phase is inherent in high Ce content Nd-Ce-Fe-B magnets, and how to harness its existence and exert its beneficial effects on magnetic properties is an essential topic in the development of these magnets. In this work, we reveal the positive impact of the REFe2 phase on coercivity enhancement by designing the RE-rich B-lean composition in the Nd-Ce-Fe-B sintered magnet with 30 wt. % Ce replacing Nd. The coercivity in the as-sintered state attains 14.07 kOe and slightly increases to 14.54 kOe upon post-sinter annealing. Phase composition and microstructure analysis indicate that the Fe-storage effect of the REFe2 phase immobilizes a large amount of Fe elements in the triple junctions, resulting in the development of a continuous Fe-lean non-ferromagnetic grain boundary phase with thickness exceeding the exchange length. In addition, the magnetization and demagnetization behaviors were analyzed by the recoil loops to reveal the coercivity mechanisms. This work demonstrates that, in addition to improving wettability, the Fe-storage effect of the REFe2 phase positively influences coercivity.

Evolution of microstructure and properties of nanocrystalline NiCo alloy under high-energy laser shock

In this study, nanocrystalline NiCo alloy was prepared through electrodeposition and subjected to high-energy laser shock (HELS) treatment to investigate the influence of laser shock on the microstructures and properties. An analysis of phase composition, microstructural evolution, texture evolution, and hardness was conducted. The results indicated that under HELS, there was no change in phase composition, while there was a slight reduction in grain size, as well as in the quantities of Low-angle grain boundaries (LAGBs) and twin boundaries (TBs). The texture evolution revealed that HELS led to a more uniform overall texture due to grain boundary (GB) mediate deformation mechanisms, along with the generation of a significant amount of 9R phases, causing a shift in texture orientation from (110) to (100). The internal structure of nanocrystalline NiCo showed an accumulation of numerous dislocations post-laser shock, with randomly oriented dislocations interacting to form Lomer-Cottrell Locks (L-C Locks) and 9R phases. Additionally, interactions with large stacking faults (SFs) also resulted in their dissociation into multiple 9R phases. The hardness enhancement was mainly attributed to the accumulation of dislocations within the grain and the generation of a significant quantity of 9R phases.

Novel ACr2O4 (A = Mg, Cu, Ni)/MIL-101(Cr) photocatalysts: Synthesis, characterization, performance prediction and applications for the photo–degradation of tetracycline hydrochloride

The Z-scheme ACr2O4 (A = Mg, Cu, Ni)/MIL-101(Cr) heterojunction photocatalysts have been synthesized by a simple method. By means of phase structure, microstructure and composition analysis, it was determined that the ACr2O4 (A = Mg, Cu)/MIL-101(Cr) photocatalysts only contained the target component, while the NiCr2O4/MIL-101(Cr) photocatalyst also contained a small amount of Cr2O3 impurities. The photocatalytic experiments showed that the degradation percentage of MgCr2O4/MIL-101(Cr) photocatalyst reached 78 % when the mass percentage of MIL-101(Cr), the catalyst content, the initial tetracycline hydrochloride concentration, pH value and illumination time were 10 %, 1 g/L, 50 mg/L, 7 and 120 min, respectively. The neural network model can effectively predict the photocatalytic activity of MgCr2O4/MIL-101(Cr) photocatalyst. Various characterization confirmed that the holes, hydroxyl radicals and superoxide radicals are the main active species involved in photocatalytic degradation of tetracycline hydrochloride. This research will provide experimental basis and theoretical support for exploring the construction of new metal–organic framework (MOF) based heterojunction photocatalysts.

Analysis of serum phase proteins and emulsifiers on the whipping capabilities of aerated emulsions: From the perspective of air-liquid interface rheology

In aerated emulsions, the serum phase plays a crucial role in determining whipping capabilities. However, the effects of serum phase components on emulsion properties remain largely unexplored and continue to be a mystery. This study takes a micro-level approach, focusing on the air-liquid interfacial rheology by incorporating different types of surfactants (proteins and emulsifiers) into the serum phase. It systematically explores the effects on the serum phase interface, emulsion properties, whipping capabilities, and foam stability in a stepwise manner. Proteins only slightly affect the strength of the air-liquid interface, primarily improving the capacity to trap bubbles at the initial whipping stage, thereby boosting the overrun of the aerated emulsion. The high viscoelastic modulus of the interface membrane is greatly influenced by the presence of solid lipid nanoparticles of glycerol monostearate (GMS SLN), leading to a reduction in whipping time and improved surface-mediated partial coalescence. This ultimately enhances the quality and stability of the foam system. Tween 80, due to its hydrophilic properties, is able to quickly adsorb at the air-liquid interface using the Gibbs-Marangoni mechanism. This helps to expedite the end of the whipping process and ultimately improves the foam quality. On the contrary, glycerol monooleate (GMO), a lipophilic emulsifier for liquids, struggles to effectively adsorb at the interface, leading to decreased stability of the air-liquid interface in the system and resulting in poor whipping capabilities. This paper delves into the mechanism by which different surfactants affect the whipping capabilities of aerated emulsions through an analysis of serum phase composition, laying the groundwork for enhancing formulation design.

Recycling of environmental harmful industrial wastes in eco-friendly building materials production suitable for specific applications

Sustainable building materials are one of the main principles to achieve sustainable construction. It refers to the potential of utilizing environmentally harmful industrial wastes to reduce the consumption of raw materials/energy used in producing ordinary Portland cement (OPC). Ground-granulated blast-furnace slag (GGBFS), lead-bearing sludge (LBS), metakaolin (MK) and fly ash (FA) were used in this work to develop eco-green binding materials with several advanced applications. Five specimens were prepared, including a control specimen (100 % GGBFS, S0) and four ternary-blended geopolymers (TBGs; GGBFS/LBS/FA and GGBFS/LBS/MK) with different proportions. The experimental work examined the mix-design's influence of the TBGs on the fresh/hardened characteristics and resistance against elevated-temperature (200–900 °C), high-dose gamma-radiation (1000–3000 kG y) and mico-organisms (Salmonella-typhi, Bacillus-Cereus, Aspergillus-oryzae and Aspergillus-fumigatus). Also, the XRD, TGA/DTG (phase composition analysis) and SEM/EDX (microstructure analysis) were studied. The findings revealed that LBS significantly reduces workability compared to MK and FA. Although the LBS, MK, and FA mixture elongated the setting time, its values are still within acceptable limits. The strength values obtained by TBGs after 28 days ranged from 51.0 to 66.7 MPa, revealing that these wastes are good alternatives to OPC. TBGs proved effective in resisting elevated-temperatures and high-dose gamma-radiation compared to S0 by forming highly-stable zeolitic compounds. The S0 specimen cannot hinder Salmonella typhi's growth; unlike TBGs, the existence of PbO2, Fe2O3, and TiO2 in the matrix inhibits all microorganisms' growth.

Laser and thermal control over structure and magnetic properties of PrDy-FeCo-B microwires

Magnetic microcombs are necessary in microrobotics, MEMS technologies, actuator and magnetic flow analyzer industries. Usually, magnetic microcombs are artificial linear magnets of periodic shape. We propose another type of microcombs based of microwires, where periodicity of magnetization is caused by equidistant alternation of natural domains. We have demonstrated the presence of quasi-periodic radial magnetization and the effect of temperature and magnetic field on magnetic relief in PrDyFeCoB microwires. Accurate analysis of chemical, phase and structural composition of the microwires allowed us to reveal necessary conditions for the creation of periodical magnetic relief. Annealing affects magnetic relief and changes structure of initially amorphous microwires. Crystal structure of inclusions enriched with Fe and Co instead of Dy and Pr is body-centered cubic (BCC), while the bulk of the microwire has tetragonal structure. We have found laser stimulated amorphization of surface of PrDy-FeCo-B microwires. Partial restoration of the amorphous structure in polycrystalline microwires under single laser pulse of irradiation of 1mJ power and 120 ns duration has been found in 1–2 μm depth.

Impact of barium oxide on the structure and surface properties of glass-crystalline glazes

The influence of barium oxide on glazes in the SiO2-Al2O3-CaO-MgO-K2O system was investigated. Samples were prepared with 0, 2.5, 5 and 7.5 wt% of barium oxide added to this system. The glazes were fired at 1240 °C and the structure and surface properties were determined. Qualitative and quantitative analyses of phase composition, surface properties, structural mid-infrared analysis, and microstructure were performed.Diopside was detected in all glazes as the MgO content was higher than 2.5 wt%. Hyalophane crystals were observed when the BaO content increased to 5 wt%. Mid-infrared studies showed that the appearance of crystalline phases ordered the structure of the glazes; on the other hand, the amorphous phase increased its disorder related to the higher amount of modifying barium cations. The addition of barium oxide did not significantly affect the color of the surface but caused an increase in roughness due to surface crystallization. The microhardness increased with an increased amount of barium in the amorphous phase.

Boriding of Low-Carbon Steel by Plasma Method: Microstructure and Coating Properties

In materials science, steel boration is a promising type of thermochemical diffusion process, the purpose of which is the introduction of hard and wear-resistant boride particles into the surface layers of the metal. The main disadvantage of boration is the fragility of borated layers, especially boride. Currently, there are promising methods for the formation of a composite structure, which are based on the treatment of surface layers of steels with concentrated energy flows (laser, electron beam and plasma). The work includes studies of microstructure, hardness measurements, analysis of phase composition, and determination of chemical composition in local locations, wear tests under various conditions, and adhesion testing of the coatings obtained after plasma boration. As the degree of alloying of the molten layer decreases in the direction from the surface to the base metal, zones of overeutectic, eutectic and pre-eutectic types with a different combination of structural components are formed. The material obtained after borating a mixture of 40% B + 10% Fe is characterized by the highest level of microhardness, which is 1000...1300 HV. The highest results in friction tests are provided by boration of a powder mixture of 40% B + 10% Fe.

Enhancing the high-temperature oxidation resistance of C-103 niobium alloy via hybrid treatment combining nickel plating with molten-salt siliconising

ABSTRACT A multi-phase silicide protective coating was prepared by electroplating nickel on the surface of C-103 niobium alloy (89Nb–10Hf–1Ti), followed by molten-salt non-electrolytic siliconising to enhance the high-temperature oxidation resistance of the substrate. The phase composition, microscopic morphology and elemental analysis of the coating were analysed via X-ray diffraction, scanning electron microscope, energy-dispersive spectrometer and hardness distribution. Oxidation characteristics were evaluated by comparing the oxidation inhibition effect of the coating on niobium alloy substrate and that of coating prepared via molten-salt infiltration alone at a constant temperature of 1100°C for 9 h. Results show that a silicide infiltration coating containing about 200-μm-thick compound layer with Ni2Si, NiSi, Nb5Si3, NbSi2, Ni3Si2 and TiNiSi multi-phase composition and ∼10–15-μm-thick diffusion layer were dense with few defects. In the hybrid synthesis process, the upper electroplated nickel coating can promote and modify the growth of subsequent siliconised coating. The duplex prepared silicon infiltration coating can reduce the oxidation rate of niobium alloy substrate by about 1/10, indicating good high-temperature oxidation resistance. This is because the siliconised coating is considerably thick, has a dense blocking structure and generates Ni4Si7Ti4, thereby blocking oxygen.

Discrepancy evaluation in mechanics and corrosion resistance of reactive plasma sprayed TiN coatings fabricated under different heat treatment

Ceramic coatings have positive feedback to annealing treatment, but improper annealing treatment can also bring disastrous consequences. In this article, a thick TiN coating without a bonding layer was prepared by reactive plasma spraying technology and then subjected to heat treatment at three different temperatures in atmospheric and argon atmospheres. By exploring the hardness, modulus, and corrosion resistance of the coatings, combined with analysis of microstructure, phase composition, and interatomic bonding conditions, it was found that the TiN coating exhibited the lowest porosity after atmospheric heat treated at 500 °C. Meanwhile, it also showed the highest hardness, modulus, and optimal corrosion resistance. After heat treated at 650 °C in the atmosphere, the protective performance of the coating was decreased, but it was still far superior to the as-sprayed coating. The coating after heat treated in the argon atmosphere did not achieve ideal performance. The coating heat treated at 650 °C even exhibited inferior comprehensive performance to the as-sprayed coating. Therefore, it was summarized that the atmospheric environments and the temperature above the phase transition temperature were suitable for obtaining the optimal TiN coating.

Thermal cycling behavior of Srx(Zr0.9Y0.05Yb0.05)O1.95+x thermal barrier coatings by suspension plasma spraying

AbstractThe thermal barrier coatings (TBCs) consisting of Srx(Zr0.9Y0.05Yb0.05)O1.95+x were prepared using the suspension plasma spraying (SPS) method. Precursor suspensions were prepared via co‐precipitation for this purpose. Detailed microstructural, phase composition, and phase content analyses were conducted on these coatings, designated as SZYY‐1 (x = 1.0), SZYY‐2 (x = 0.9), and SZYY‐3 (x = 0.8). Additionally, the coatings underwent a thermal cycling test at 1121°C for 1 h. To assess the morphology of thermally grown oxide (TGO) in a real coating, a finite element model was employed. SPS‐SZYY‐2 with columnar crystal structure was found to have the highest number of thermal cycling, up to 345 times. The thermophysical high‐temperature properties of the coating can be effectively improved through suitable second‐phase content. Microstructural and finite element analyses revealed that stress, primarily caused by the continuous growth of the Co3O4, NiO and Spinel (CNS) layer within TGO, was the predominant factor leading to coating failure. At elevated temperatures, transverse cracks formed at the interface between the bond coating and ceramic top coating due to mismatched thermal expansion and sintering effects, ultimately leading to coating degradation. Therefore, reducing the generation rate of large stresses in the coating, especially shear stresses, can effectively prevent the generation and propagation of transverse cracks and increase the thermal cycling life of TBCs.

Morphology-Dependent Photocatalytic Activity of Nanostructured Titanium Dioxide Coatings with Silver Nanoparticles.

This study aims to improve the photocatalytic properties of titanium dioxide nanorods (TNRs) and other related nanostructures (dense nanorods, needle-like nanorods, nanoballs, and nanoflowers) by modifying them with silver nanoparticles (AgNPs). This preparation is carried out using a two-step method: sol-gel dip-coating deposition combined with hydrothermal crystal growth. Further modification with AgNPs was achieved through the photoreduction of Ag+ ions under UV illumination. The investigation explores the impact of different growth factors on the morphological development of TiO2 nanostructures by modulating (i) the chemical composition, the water:acid ratio, (ii) the precursor concentration involved in the hydrothermal process, and (iii) the duration of the hydrothermal reaction. Morphological characteristics, including the length, diameter, and nanorod density of the nanostructures, were analyzed using scanning electron microscope (SEM). The chemical states were determined through use of the X-ray photoelectron spectroscopy (XPS) technique, while phase composition and crystalline structure analysis was performed using the Grazing Incidence X-ray Diffraction (GIXRD) method. The results indicate that various nanostructures (dense nanorods, needle-like nanorods, nanoballs, and nanoflowers) can be obtained by modifying these parameters. The photocatalytic efficiency of these nanostructures and Ag-coated nanostructures was assessed by measuring the degradation of the organic dye rhodamine B (RhB) under both ultraviolet (UV) irradiation and visible light. The results clearly show that UV light causes the RhB solution to lose its color, whereas under visible light RhB changes into rhodamine 110, indicating a successful photocatalytic transformation. The nanoball-like structures' modification with the active metal silver (TNRs 4 Ag) exhibited high photocatalytic efficiency under both ultraviolet (UV) and visible light for different chemical composition parameters. The nanorod structure (TNRs 2 Ag) is more efficient under UV, but under visible-light photocatalyst, the TNRs 6 Ag (dense nanorods) sample is more effective.

Modification of cement-based circulating fluidized bed combustion slag: Physical grinding and chemical excitation

This study investigates the effects of physical grinding (ball, impact, and jet milling) and chemical modification (using various dosages of Na2SO4, CaO, triethanolamine (TEA), and their composite modifiers) on CFBCS. The fluidity, flexural strength, compressive strength, and expansion rate of different modification methods were tested. Microstructural and phase composition analyses were conducted using X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, mercury intrusion porosimetry, and thermogravimetry-differential thermogravimetry. The results indicated that impact milling improved mortar fluidity by 2.9 % compared to ball milling, while jet milling reduced it by 5.7 %. Chemical modifications decreased paste fluidity but increased mortar strength and reduced expansion rates. Impact milling and jet milling improved 28-day compressive strength by 13.76 % and 16.01 %, respectively, and reduced the 90-day expansion rate by 0.007 % and 0.012 %, respectively. Composite chemical modification (CM-C) enhanced 28-day compressive strength by 23.88 % and reduced the 90-day expansion rate by 0.019 %. Microscopic analysis shows that modification reduced the pores and pore size of the mortar while increasing the hydration products. After TEA modification, rod-shaped AFt forms a reticulated structure, with C–S–H gel and CH crystals adhering to it. The hydration products of CFBCS mortar formed a network after jet milling, and the addition of composite modifiers resulted in a layered, dense structure.

CaTiO3 nanoparticles as functional additives for the BaTiO3-based X8R type dielectric ceramics

This research investigates the potential of Calcium titanate (CaTiO3 or CT) nanoparticles as functional additives to enhance the dielectric properties of Barium titanate (BaTiO3 or BT)-based ceramic dielectrics. To address the need for high-temperature stability in MLCC (multilayer ceramic capacitor) applications, especially within the automotive and aerospace sectors, we have explored BT-based complex perovskite solid solutions comprising various cation substitutions, including Ca2+ and Yb3+, into barium titanate (BT) as a method to suppress the dielectric property anomaly near the Curie temperature effectively. The focus is on the impact of the application of CT nanoparticles as additive materials on phase formation, microstructure development, and dielectric behavior of the resulting ceramics to align with the Extended 'Temperature Coefficient of Capacitance (TCC)' criteria defined by the EIA X8R specification. When the hydrothermally synthesized CT nanopowder was applied in the Ca-doped BT ceramics fabrications as source material of the Ca dopants, it was beneficial to achieve both temperature stability and high dielectric constant. The CT nanoparticles are believed to play multiple roles during the solid-state reaction with BT and rare earth dopant (Yb). Since the Yb3+ ions can be more easily dissolved into the CT lattice than BT with their amphoteric character, the CT nanoparticles in the BT-CT-Yb2O3 mixture can act as an intermediary, dissolving the Yb3+ first in its A- or B-site before the final solid-solution formation with the BT. The sequential substitutions of the Yb3+ and Ca2+ into BT via CT nanoparticles could affect the site occupancy of Ca2+ in the BT lattice, which is very important in determining the dielectric properties of the Ca-doped BT processed in reducing atmospheres. Through a comprehensive experimental approach, including phase composition analysis via X-ray diffraction (XRD) and microstructural examination using Field Emission Scanning Electron Microscopy (FE-SEM) and Transmission Electron Microscopy (TEM), this work reveals the significance of synthetic methodology and dopant incorporation strategy on achieving a desired core-shell microstructure and improved dielectric performance. This research underscores the efficacy of CT nanoparticles as a promising route towards the development of BT-based dielectric ceramics with superior temperature stability, offering valuable insights for the advancement of MLCC technology to cater to high-temperature applications.

A developed highly selective and sensitive electrochemical sensor using gold nanoparticles on Cerium Stannate/MXene as an electrode matrix for detection of metol in various environmental and biological samples

Metol (MTL) is a highly significant organic compound that plays a crucial role in numerous applications as a monochromatic material. It has an impact on humans, plants, and animals and it raises serious environmental concerns. The present scenario necessitates the development a rapid, cost-effective, precise, and specific method for detecting metol in environmental and biological samples. In this study, the electrochemical sensor was developed using a modified electrode based on the Au@Ce2Sn2O7/MXene nanocomposite. The nanocomposite was thoroughly examined through phase composition analysis, elemental analysis, and morphological studies. The modified electrode exhibits exceptional selectivity, cyclic stability, storage stability, and reproducibility. The proposed sensor shows a wide linearity range (0.00125 to 1021.96 μM), low detection limit (5.63 nM), and high sensitivity (0.403 μA·μM–1·cm–2). The suggested sensor's consistency was confirmed by real-time monitoring of MTL in several environmental and biological samples with a high percentage of recovery.

The study of interaction of the high energetic plasma and electron pulses with multicomponent alloy surface

This paper investigates the impact of high-energy sources, namely, high-energy plasma pulses and high-energy electron beam pulses, on materials in the form of layer through separate and combined exposures. Experimental setups utilizing a Rod Plasma Injector (RPI) and an electron gun were employed for irradiation tests. The studies involved pre- and post-treatment analysis of morphology, chemical, and phase composition using scanning electron microscopy and x-ray diffraction measurements. Surface modifications under different exposure conditions were characterized, revealing that both sources induced significant alterations in surface composition and crystal structure. These interactions result in a more uniform chemical composition, reduced surface roughness, and a shift from an amorphous phase to a nanocrystalline or amorphous-nanocrystalline state. The results underscore the potential of high-energy sources for efficient surface engineering, offering opportunities for customized material surface modifications through meticulous adjustment of these generation parameters.

Comparative Analysis of Chemical and Phase Compositions of Rolling Scale of Metallurgical Enterprises

Comparative Analysis of Chemical and Phase Compositions of Rolling Scale of Metallurgical Enterprises

Optimizing the grain boundary structure of sintered Nd-Fe-Co-B magnets by Dy-Al-Cu alloys grain boundary diffusion

The substitution of Fe by Co can effectively increase the Curie temperature of Nd-Fe-B magnets. However, the enrichment of Co in the grain boundary phase makes the grain boundary phase change from nonmagnetic to ferromagnetic, which has a harmful effect on the coercivity. In this paper, Dy70Al10Cu20 alloy was used as the diffusion source for grain boundary diffusion of sintered Nd-Fe-Co-B magnets. The magnetic properties and microstructure of the magnets were investigated by controlling the coating thickness of the diffusion source (thickness of 0.03 mm, 0.09 mm, and 0.15 mm). The results show that the coercivity of the magnet after diffusion is increased to 17.63 kOe, which is 9.69 kOe higher than that of the undiffused magnet. The phase composition analysis shows that the original magnet contains the soft magnetic 2:17 phase, and the 2:17 phase is significantly reduced after diffusion. The microstructure observation shows that the main phase is connected and the grain boundary phase is absent in the high Co original magnet. After diffusion, the thin grain boundary phase in the magnet increases, which effectively isolates the main phase grains. Dy-rich shell is formed on the surface of the main phase grain, which is beneficial to the improvement of coercivity. Therefore, magnetic hardening of Dy-rich shells and exchange-decoupling strengthening of adjacent 2:14:1 grains isolated by intergranular phases contributed to further coercivity increment Hcj of magnet simultaneously. Studies have shown that grain boundary diffusion is an effective way to improve the microstructure of Nd-Fe-Co-B magnets.