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In mechanical applications, defect-based fatigue cracking is a significant strength-limiting failure mode of additively manufactured composites that is not yet fully understood in the service environment. In this paper, axial loading tests were carried out at 25 ℃ and 450 ℃, and then the effects of temperature on the long-life fatigue properties of the TiC-reinforced Ti6Al4V composite fabricated by Laser Powder Bed Fusion (LPBF) were investigated by combining the techniques of electron backscatter diffraction, X-ray computed tomography, and 3D morphological reconstruction. With the increase in temperature, the fatigue strength of the LPBF TiC/Ti6Al4V composite decreases significantly. The main causes of the interior failure at both temperatures are the inhomogeneous hardening zone (IHZ) formed by TiC agglomeration and the pore defect generated during the manufacturing process. The presence of brittle IHZ and pores causes stress concentration, which leads to crack nucleation. When a crack reaches the specimen surface, the combined effects of temperature and oxygen accelerate the ensuing crack propagation at high temperature. Based on the temperature effect, material properties, and the statistical distribution of defects, a model has been developed to predict the P-S-N curves at both temperatures. This model performed well in estimating the fatigue strength at 109 cycles. These findings provide new insights into the defect-related fatigue failure mechanisms and strength evaluation of the LPBF TiC/Ti6Al4V composite at different temperatures. [Display omitted] • Two defect-based cracking modes with IMZ-fisheye are revealed. • One cracking is attributed to the aggregation and debonding of TiC particles. • The other cracking is due to the irregular pores formed during LPBF. • A strength evaluation model with statistical defect size is proposed. [ABSTRACT FROM AUTHOR]

Reactive materials are functional structural materials that balance structural strength and reactivity, and their shock response is greatly influenced by the characteristics of reactive components. This article aims at understanding the shock compression and reaction of Al-Hf reactive materials with two values of the Al-Hf particle size ratio α (1 µm:10 µm and 10 µm:10 µm), which were prepared through hot pressing with a compactness (the ratio of density to theoretical maximum density) greater than 96.46%. The free surface velocity of the materials was measured in the impact velocity range of 279–865 m/s. The Hugoniot elastic limit (HEL), spall strength, and Hugoniot relationships under shock stresses of 1.83–14.46 GPa were analyzed on the basis of the microstructure and phase change. Continuous Al phase was formed in the sample with α = 0.1, while more Hf–Hf contact and crushed Hf appeared in the sample with α = 1. The velocity profiles presented clear signs of the linear growth to the HEL, the slow increase to the peak, and the subsequent pullback, indicating the transition from elastic to plastic and spall behavior. The HEL fluctuated significantly with increasing shock stress, while the spall strength first increased and then decreased. The sample with a continuous Al phase exhibited a lower HEL (0.52–0.97 GPa) and higher spall strength (0.31–0.46 GPa). The microstructure had a significant effect on the shock induced chemical reaction of the materials. Shock velocity was linearly related to particle velocity for the α = 0.1 sample, while a notable quadratic growth was observed for the α = 1 sample owing to self-reactions under the lower shock stress (5.32 GPa). The intermetallic Hf 4 Al 3 observed in the recovered product by X-ray diffraction further verified the phenomenon. • Nearly fully dense Al-Hf reactive material was prepared by hot pressing. • The effect of microstructure on the shock behaviors and reaction characteristics was investigated. • The sample with larger particle size of Al exhibited higher Hugoniot elastic limit and lower spall strength. • Intermetallic Al 4 Hf 3 was observed in the recovered samples, and sample with larger Al are more prone to reactions. [ABSTRACT FROM AUTHOR]

ZrN and TiNiN nanolayers are alternately deposited on silicon substrate by magnetron sputtering. A series of ZrN/TiNiN nano-multilayer films with different Ni contents are prepared by varying the Ni:Ti volume ratio of the targets. The effects of Ni content on the microstructures and mechanical properties of ZrN/TiNiN nano-multilayer films are studied by X-ray diffractometer (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM) and nanoindentation instrument. The results show that with the increase of Ni content, the crystallization degree of ZrN phase first increases and then decreases. Besides, the hardness, elastic modulus and toughness of the films also increase first and then decrease with Ni content increasing. When Ni:Ti= 1:24, the ZrN/TiNiN nano-multilayer films obtain the highest hardness, elastic modulus and fracture toughness, which are 23.2 GPa, 317.8 GPa and 2.29 MPa·m1/2, respectively. This is mainly attributed to the best columnar crystal growth of the ZrN/TiNiN nano-multilayer film. The TiNiN layer changes into face centered cubic structure under the template of ZrN layer, and grows in coherent epitaxy with ZrN layer. ● A series of ZrN/TiNiN nano-multilayer films with different Ni contents are prepared by magnetron sputtering. ● When Ni:Ti= 1:24, the ZrN/TiNiN nano-multilayer films simultaneously obtain the highest hardness and fracture toughness. ● The high hardness and toughness are due to that the TiNiN layer grows in coherent epitaxy under the ZrN layer template. [ABSTRACT FROM AUTHOR]

The overuse of antibiotics has led to the emergence of drug-resistant bacteria, presenting a significant risk to public health and human well-being. A novel antibacterial material with safe and effective antibacterial properties is a viable strategy to address these issues. In this work, Al ions doped CuS particles (CuS@Al) with a flower-like nanostructure were synthesized through a simple hydrothermal method, exhibiting good photothermal and photodynamic antibacterial properties. The morphological, microstructural and crystallinity of CuS@Al were evaluated by SEM, EDS, TEM, FTIR, XRD and XPS analyses. The introduction of Al ions significantly enhanced the photothermal effects of CuS@Al, and the temperature increased from 50.7 ℃ (CuS) to 58.1 ℃ (CuS-6) under irradiation (808 nm, 2.0 W·cm−2, 10 min). The resulting CuS@Al exhibited a good photothermal conversion efficiency, effective release of reactive oxygen species (ROS), and remarkable photothermal antibacterial activity. Both E. coli and S. aureus were completely inactivated by CuS@Al (0.5 mg/mL) under photodynamic conditions. The synthesis of CuS@Al provides a strategy for creating highly effective antibacterial materials in particulate form. [Display omitted] • After incorporation with Al ions, the photothermal conversion efficiency of Al-doped CuS (CuS-6) was enhanced by 47.28 % compared to CuS. • With a 2.0 W·cm−2 NIR laser irradiation, the Al doped CuS could inactivate 99.99 % of S. aureus and E. coli O157:H7 within 10 min. • The Al doped CuS (CuS-6) showed excellent photodynamic antimicrobial properties against 100 % of S. aureus and E. coli O157:H7 under simulated light sources within 10 min. [ABSTRACT FROM AUTHOR]

This study showcases the interfacial magnetoelastic effect observed in flaky FeSiAl alloy powder absorbents, aimed at enhancing permeability in the decimeter-wave band for better absorption performance through Cr doping via wet ball-milling and subsequent annealing processes. The wet ball milling process facilitates the formation of a lamellar structure by inducing slip along shear stress in DO 3 and α-Fe nanocrystals. During annealing, the introduced Cr element partially impedes the transition from the α-Fe phase to the DO 3 phase, thereby amplifying the difference in magnetostrictive coefficients between these phases. Consequently, the flaky FeSiAlCr powders exhibit notably increased initial permeability and resonance frequency, particularly around 3 GHz, owing to domain rotation in the DO 3 phase. In comparison to previously reported counterparts, the composite derived from these powders demonstrates a significant enhancement in the real part of effective permeability by approximately 66 %, alongside a 17 % reduction in density. Consequently, this composite exhibits a lowered reflection loss of below −5 dB within the frequency range of 0.7–3 GHz, reaching a minimum of −11 dB at 1.57 GHz, specifically with a thickness of 1.6 mm. These findings present an effective strategy for enhancing the magnetic permeability of alloy powders. The resultant microwave absorbing materials hold promising applications in stealth technology and wireless communication electronics. • Flaky FeSiAlCr alloy powder absorbents exhibit an interfacial magnetoelastic effect. • The effect generated a dual dispersion in permeability, in line with a stress model. • The 1.6 mm-thick-composite has a RL below −5 dB in 0.7–3 GHz with a minimum of −11 dB. [ABSTRACT FROM AUTHOR]

The coercivity of the sintered Nd-Fe-B permanent magnets prepared by the dual-main-phased (DMP) process can be significantly enhanced. This paper provides a comprehensive review of this method. The methodology and process of the DMP method are outlined, along with its mechanisms and advantages in improving magnet performance. Furthermore, this study highlights the outstanding performance of DMP magnets in terms of mechanical properties and corrosion resistance. Lastly, the future development trends and research directions for the DMP method are explored, such as optimizing process parameters, exploring novel alloy designs, and developing higher-performance magnet materials. [ABSTRACT FROM AUTHOR]

The bimetallic sulfide of NiCo 2 S 4 generally show better electrochemical performance than its bimetallic oxide counterpart in supercapacitor electrode applications. In this work, we theoretically explain their essential differences in reaction mechanisms through density functional theory, including their OH- adsorption energy, energy band structure, total and projected density of states, as well as d-band center of Ni and Co, which confirms the intrinsic advantage of NiCo 2 S 4 over NiCo 2 O 4 as electrode material for alkaline supercapacitors. Then, through electrospinning, we fabricate porous nanofibers of NiCo 2 S 4 -NF and NiCo 2 O 4 -NF with similar porous, fibrous morphology stacked by nanoparticles, of which NiCo 2 S 4 -NF gives obviously superior performance in alkaline electrolyte as supercapacitor electrodes, verifying the theoretical prediction. Moreover, an rGO coverage layer was in-situ incorporated to fabricate porous nanofibers of rGO@NiCo 2 S 4 -NF, which includes an additional surface rGO wrapping layer. The 1D and porous architecture renders rGO@NiCo 2 S 4 -NF more exposed OH- adsorption sites to induce active redox reactions, while the rGO coverage further stabilized the nanofibers and ensures inter-fiber charge transfer. Due to the combination of morphology optimization and carbon combination, rGO@NiCo 2 S 4 -NF delivers enhanced capacity, cycle stability and rate ability than NiCo 2 S 4 -NF and NiCo 2 O 4 -NF. Using rGO@NiCo 2 S 4 -NF, asymmetric supercapacitors are assembled, which also exhibits promising energy densities and power densities. [Display omitted] • Theoretical verification of Ni-Co sulfide's advantage in reaction kinetics in alkaline supercapacitors. • The porous and fibrous morphology of NiCo 2 S 4 with surface rGO decoration endows rich OH- adsorption sites, effective charge transfer and active redox reactions. • The enhanced capacity, cycle stability and rate ability of rGO@NiCo 2 S 4 -NF enables asymmetric supercapacitor devices with high performance. [ABSTRACT FROM AUTHOR]

Layered sodium ion cathode material is increasingly popular due to the superiority of low-cost and excellent rate performance. However, it usually suffers from poor capacity retention arising from microcracks during multiple-phase transitions. Herein, a Ce-doped O3-type cathode material NaNi 0.5 Mn 0.5 O 2 (NNM) was synthesized by high shear mixer-assisted precipitation of oxalate precursors. Using the characterizations of XRD, XPS, HRTEM, GITT, etc., the results indicate that Ce dopants can adjust the initial phase structure as well as postpone the phase transition in such O3-type material. The optimal NNM-0.06Ce shows a superior initial discharge capacity of 128.3 mAh g−1 and a retention of 85.96% after 100 cycles (1.5–4.0 V, 1 C, 25 °C), as well as superior rate performance of 107 mAh g−1 at 5 C. HAADF-STEM images disclose that the doped Ce atoms are probably located in the sodium layer of the cathode material, moreover, DFT calculations reveal that the Ce dopant is prone to occupy the Na site and cause charge rising of Ni and Mn. In-situ XRD tests indicate that the earlier formed O1 phase induced by Ce dopants can postpone the phase transition and increase the reversibility of the cathode, therefore improving the electrochemical performance of cathode materials. [Display omitted] • Ce-doped NaNi 0.5 Mn 0.5 O 2 was synthesized by high shear mixer-assisted precipitation. • NNM-0.06Ce has a capacity of 128.3 mAh g−1 and a 100th retention of 86% (1.5–4.0 V). • Ce dopant is prone to occupy the Na site, enhancing Na+ diffusion in the O3-type cathode. • NNM-0.06Ce has delayed transition from O3 to P3 phase in charging. [ABSTRACT FROM AUTHOR]

First, UV stopped-flow profiles were measured upon rapid mixing a series of soluble metal salt precursors with the Na 2 CO 3 solution to detect the kinetics of the complicated process involving the insoluble material formation reaction and the subsequent nanoparticles growth. Comparing the kinetic curves in 60 ms with 300 ms at 45–65 °C, it illustrates that the formation reaction of insoluble transition metal carbonates occurs rapidly (shorter than 60 ms) and precipitates as nanoparticles that act as the seeds for the subsequent particle growth. Then, a High-Shear co-Precipitation (HSP) method was developed to synthesize uniform LiNi 0.6 Co 0.2-x Mn 0.2 La x O 2 , overcoming the inherent difference of tens of magnitude in the solubility product constant (K sp) of individual carbonates. The synthesized LiNi 0.6 Co 0.198 Mn 0.2 La 0.002 O 2 exhibits an initial discharge capacity of 200.5 mAh g−1, superior to LiNi 0.6 Co 0.2 Mn 0.2 O 2 (194.7 mAh g−1, 0.1 C). In addition, the phosphorous coating of LiNi 0.6 Co 0.198 Mn 0.2 La 0.002 O 2 increased the capacity retention up to 86.4 % (400th, 5 C). DFT calculations indicate that La-intercalation can enlarge the Li+ layer spacing and reduce the Li+ migration energy barrier. This work illustrates the importance of the pulverization effects exerted by the High-Shear force on various insoluble nanoparticles during the initial rapid mixing period, providing a useful tool for manufacturing heteroatom-intercalated bulk nickel-rich cathode material. [Display omitted] • Insoluble carbonates nanoparticles are mixed evenly by ultrafast High-Shear force. • LiNi 0.6 Co 0.2-x Mn 0.2 La x O 2 is synthesized via a High-Shear co-Precipitation method. • LiNi 0.6 Co 0.198 Mn 0.2 La 0.002 O 2 shows an initial capacity of 200.5 mAh g−1 (0.1 C). • P-coating synergically improves the retention to 86.4 % (400th, 5 C). • La-intercalation enlarges the Li+ layer spacing of nickel-rich cathode. [ABSTRACT FROM AUTHOR]

The hydrogenation kinetics of Sm 26.2 Co bal Fe x Cu 4.0 Zr 2.3 (x = 23, 27 in wt%) strips (Fe23 and Fe27 strips) has been investigated. The phase composition, morphology, surface roughness and the inner pores of the strips also have been studied by XRD, SEM, optical profilometer and non-destructive micro-computerized tomography. Compared to Fe23 and Fe27 strips, heat-treated strips (H-Fe23 and H-Fe27) and corrosion heat-treated strips (HC-Fe23 and HC-Fe27) exhibit a relatively higher hydrogen absorption capability. Fragmentation behavior occurs in HC-Fe23, H-Fe27 and HC-Fe27 strips during hydrogenation. After heat treatment, the grain size and inner pore size increase, leading to the disappearance of fine crystal strengthening and the concentration internal stress. For corrosion-treated strips, increased surface roughness and deeper grooves result in the formation of surface stress concentration, ultimately leading to an increased susceptibility to hydrogen embrittlement. Accordingly, the increase of grain size, inner pore size and rougher surface is beneficial for hydrogenation and hydrogen embrittlement. • The effect of heat- and corrosion- treatment on grain size, inner pores and surface roughness of the strips are - studied. • The reduced fine grain strengthening and pronounced internal stress concentration lead to a higher HAC. • Corrosion treatment promotes hydrogen absorption and the susceptibility of hydrogen embrittlement. [ABSTRACT FROM AUTHOR]

Two ternary heterojunction composites, namely hollow-structured TiO 2 /CdS/Au and hollow-structured TiO 2 /Au/CdS, were successfully synthesized by preparing hollow-structured TiO 2 first, followed by the deposition of Au and CdS (with different deposition sequences), respectively. In these two composites, hollow-structured TiO 2 nanotubes provide 1D structure with large specific area, which facilitate the immobilization of CdS and Au nanoparticles and the transfer of electrons. CdS is visible-light responsive and Au nanoparticles can improve photocatalytic efficiency by the formation of schottky barrier and surface plasmon resonance effect (SPR). The structures and phases, morphologies, surface and optical properties of the two composites were systematically characterized. TiO 2 /CdS/Au ternary heterojunction composite has efficient light absorption ability and excellent performances in photocatalytic hydrogen generation (up to 3600 μmol h−1 g−1), which is more than 4 times higher than that of TiO 2 /Au/CdS (800 μmol h−1 g−1). Therefore, in this way, we present a promising strategy to construct hybrid photocatalysts for hydrogen production. • Hollow-structured TiO 2 /CdS/Au and TiO 2 /Au/CdS heterojunction photocatalysts were synthesized. • TiO 2 /CdS/Au exhibited excellent visible-light activity on H 2 generation. • The hollow-structured TiO 2 /CdS/Au improved the separation and transfer efficiency of electrons. [ABSTRACT FROM AUTHOR]

To respond to the gradually increasing demand for thermal stability of sintered NdFeB magnets and grasp the evolution rules of their phase structure, research on sintered Nd-Dy-Fe-Co-B magnets was conducted. The magnets used in this study were prepared by the powder metallurgy method (Strip Casting + Hydrogen Decrepitation + Jet Milling). The room temperature magnetic properties of the magnet sample were B r = 11.45 kGs and H cj = 22.42 kOe, with a low-temperature coefficient of B r (α Br (20 °C∼100 °C) = −0.059 %/°C) and a high Curie temperature (T c = 460 °C). Based on the microstructure observation, there were planar anisotropic soft magnetic phase Nd 2 Co 17 within grain boundaries and the "Cu-Co Opposite Distribution". Low-melting-point binary alloy Pr 80 Cu 20 was introduced into the magnet by grain boundary addition to eliminate Nd 2 Co 17 phases and improve the coercivity. After the grain boundary addition, the "Cu-Co Opposite Distribution" was used to eliminate the Nd 2 Co 17 phase, the grain boundary structure was optimized, and the coercivity was increased by approximately 2.6 kOe, which was approximately 10 % of the total coercivity. Therefore, Cu-containing low-melting-point binary alloy grain boundary addition is an effective method for optimizing the grain boundary structure of Nd-Dy-Fe-Co-B magnets, thereby improving the high-temperature stability and coercivity. • The "Cu-Co Opposite Distribution" was found in the Nd-Dy-Fe-Co-B magnets. • The planar anisotropic soft magnetic phase Nd 2 Co 17 was found in grain boundaries. • Pr 80 Cu 20 binary alloy grain boundary addition is an effective method for optimizing the grain boundary structure. • The orientation behavior of sintered NdFeB magnets cannot be changed by the substitution of Co. [ABSTRACT FROM AUTHOR]

Crystallization of amorphous alloy is a commonly used method to fabricate nanocomposite permanent magnets. However, the effect of the hyperfine structures of amorphous alloy on microstructure evolution and magnetic properties of the obtained nanocomposites is far from understood. Here, amorphous Nd 9 Fe 85 B 6 alloys with different hyperfine structures, i.e., different short-range orders (R s = 0.80–0.91 nm), were prepared via melt spinning. The effects of the hyperfine structure on crystallization behavior, microstructure, and magnetic properties of the material upon thermal annealing were investigated in depth. Crystallization kinetics calculations show that a larger R s leads to a smaller apparent crystallization activation energy, which leads to higher volume fractions of α-Fe and Nd 2 Fe 14 B. At the same time, a crystallizaition process dependent stage crystallization activation energy of Nd 2 Fe 14 B has been obtained, which is low at nucleation stage and increases with crystallization process, i.e. easy for nucleation but hard for growth, which leads to a smaller grain size of Nd 2 Fe 14 B. As a result, optimized magnetic properties were obtained in the sample with R s = 0.91 nm. • Amorphous magnetic alloys with different hyperfine structures were prepared. • A larger short-range order (R s) leads to higher contents of two main phases. • A larger short-range order leads to smaller grain size of Nd 2 Fe 14 B phase. • Crystallization kinetic was investigated to explain microstructure evolutions. • Optimized magnetic properties were obtained in the sample with R s = 0.91 nm. [ABSTRACT FROM AUTHOR]

Here, we study the homogenization behavior and microstructure of seven Ni-Al-Ti alloys with quaternary additions of γ forming elements 4Cr, 4Co, 4Ru, 4Mo, 4Hf, 4 W and 2Re. To design a homogenization treatment, the as-cast microstructure is analyzed revealing the diffusion distances x between dendrite cores and interdendritic regions. The temperatures for homogenization are determined using differential scanning calorimetry (DSC) and Thermo-Calc simulations, to be between 1150 and 1275 °C. The time to achieve homogenization is modelled based on the residual segregation index δ utilizing diffusion distance, homogenization temperature and diffusion data. Electron probe micro analyzer (EPMA) measurements show that our predictions match for the 4Cr, 4Co, 4Ru, 4 W and 2Re alloys while the 4Hf alloy shows insufficient homogenization. Transmission electron microscopy (TEM) reveals a two-phase γ/γ' microstructure after 750 °C / 24 h, whereby the 4Co and 4Ru alloys form hierarchical microstructures. We observe γ plates in the 4Co alloy and γ spheres in the 4Ru alloy. Ru in the 4Ru alloy is involved in stabilizing the morphology of γ spheres. We provide a straightforward method for the design of homogenization treatments of Ni-based superalloys and demonstrate an alloy design pathway for tailoring the phase stability of hierarchical microstructures. [Display omitted] • Residual segregation index δ modelled and compared to experimental data. • Reaction temperatures from DSC and ThermoCalc. • Suitable homogenization treatments were designed. • Co and Ru promote formation of hierarchical microstructures. [ABSTRACT FROM AUTHOR]