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The Fe50Ni50 alloy powders were successfully synthesized with the liquid phase reduction method and then treated with the transverse magnetic field of 200 kA/m. The influences of transverse magnetic field treatment on microstructures and radar absorbing properties of the powders were mainly investigated. Whether the powders were treated with the transverse magnetic field or not, the main phases of Fe50Ni50 alloy powders were FeNi 3 and a small amount of Fe 2 O 3 . Results showed that the real part of complex permeability μʹ; of the Fe50Ni50 alloy powders in 1–5 GHz increased significantly, especially at the frequency of 1 GHz, the μʹ; increased from 2.2 to 2.8 after transverse magnetic field treatment. The magnetic loss tanδm of the Fe50Ni50 alloy powders after transverse magnetic field treatment was ≥0.3 in the frequency range of 1–13 GHz and 0.7–1.05 in the frequency range of 3.5–9.0 GHz. Compared with those of the untreated powders, the wave-absorbing properties of the powders after transverse magnetic field treatment were significantly improved. The Fe50Ni50 alloy powders coatings with thickness of 1.5 mm exhibited excellent wave-absorbing properties after transverse magnetic field treatment, and the qualified absorption band width reached nearly 3 GHz when the reflectivity |R| was ≥10 dB. [ABSTRACT FROM AUTHOR]

In this paper, a type of smooth even endogeny conversion coat composed of Cu 0.86 Fe 2.14 O 4 and (Cu 0.18 Fe 0.82 )Cu 0.82 Fe 1.18 O 4 phases was successfully obtained by a conversion reaction on the surfaces of Fe 71.5 Cu 1 Nb 3 Si 13.5 B 9 V 2 amorphous alloy ribbons. In this way, its ribbon thickness was decreased about 6–8 µm equivalently. The phase composition and microstructure of the conversion coat were investigated by XRD and SEM. In addition, the adhesion test of epoxy resin and amorphous alloy ribbon was verified by dipping experiments. It is found that the interface bonding strength between the conversion coat and ribbons is strong comparatively. On one hand, the proper interface between conversion coat and epoxy resin make it easy for ribbons to be encapsulated; on the other hand, the ribbons perform better significant piezomagnetic effect than the untreated ones due to a thinner thickness. This work may be a good basic for the applications of Fe 71.5 Cu 1 Nb 3 Si 13.5 B 9 V 2 amorphous alloy ribbons in piezomagnetic sensor and other devices based on the piezomagnetism effect. [ABSTRACT FROM AUTHOR]

• The absorber with special structure design not only overcomes the problem of narrow absorption band of metamaterials, but also solves the shortcoming of weak C-band absorption effect of magnetic material absorber. • The wave-absorbing properties of the FeSiAl p /epoxy resin composite is greatly improved compared with the simple FR4 matrix material, the effective bandwidth (bandwidth with reflectance less than −10 dB) increased by 11.4 times from 0.32 GHz to 4.29 GHz, and the absorber has obvious C-band absorption effect. • After optimizing the dimensions of absorber, the FeSiAlp/epoxy resin composite absorber with a thickness of 2.2 mm reached peak simultaneously at 7.20 GHz and 15.40 GHz, and peak reflectivity reached −11.51 dB and −13.01 dB, respectively, and corresponding absorption reached 92.93% and 95.00%, respectively. The effective bandwidth reached 4.29 GHz, and the absorber had obvious absorption effect in C-band. A novel broadband incident angle independent magnetic composite metamaterial absorber with C-band absorbing effect is proposed. The wave-absorbing properties of the FeSiAl p /epoxy resin composite is greatly improved compared with the simple FR4 matrix material, the effective bandwidth (bandwidth with reflectance less than −10 dB) increased by 11.4 times from 0.32 GHz to 4.29 GHz, and the absorber has obvious C-band absorption effect. After optimizing the dimensions of absorber, the FeSiAlp/epoxy resin composite absorber with a thickness of 2.2 mm reached peak simultaneously at 7.20 GHz and 15.40 GHz, and peak reflectivity reached −11.51 dB and −13.01 dB, respectively, and corresponding absorption reached 92.93% and 95.00%, respectively. The effective bandwidth reached 4.29 GHz. The experiment basically verified the simulation results. Therefore, the absorber with special structure design not only overcomes the problem of narrow absorption band of metamaterials, but also solves the shortcoming of weak C-band absorption effect of magnetic material absorber. [ABSTRACT FROM AUTHOR]

In recent years, the development of lightweight broadband absorbers has always been pursued by researchers. In this paper, a low-frequency, broadband and lightweight absorber is designed and prepared by combining the metamaterial structure with the magnetic composite material. First of all, the quality of the absorber was low, which was 40% lower than that of traditional absorber composite materials. Secondly, the absorber had excellent absorbing effect, and its absorbing bandwidth (bandwidth with reflectivity less than −10 dB) reached 6.72 GHz, and its RL min (minimum reflection loss) value had dropped to − 23.94 dB. Finally, the absorber also had obvious effects at low frequencies, the absorber's RL min value reached − 10.10 dB at 7.36GH. Simultaneously, the experimental results also verify the above results very well. Therefore, this kind of absorber gives full play to the advantages of magnetic composite material and metamaterial structure. This design concept provides a new development path for the design of absorber materials, and will also play a huge role in promoting the application of absorbing materials in military and civilian fields, such as the research and development of a new generation of stealth fighters. [ABSTRACT FROM AUTHOR]

Titanium alloys play an important role in lightweight aircraft engines owing to their low densities and high specific strengths. However, an increase in the thrust-to-weight ratio causes the engine operating temperature to be much higher than the service temperature, which deteriorates the oxidation resistance and mechanical properties. In this study, yttria-partially stabilised zirconia (8YSZ)/NiCrAlY thermal barrier coatings (TBCs) with a bimodal structure were prepared on Ti–6Al–4V by using spark plasma sintering (SPS) to improve the service temperature. The distinctive bimodal structure possessed dense particle contacts and a uniform distribution of porous nanoparticles, resulting in higher strain tolerance, sintering resistance, and lower thermal conductivity. Therefore, the bimodal structure prepared by lowering the SPS preparation temperature increased the high-temperature service time of TBCs on titanium alloy. The ceramic top coating (TC) and bond coating (BC) were well connected after isothermal oxidation at 800 °C for 100 h. The TBCs only shed 6% of their surface area at high temperature and large-angle bending. In addition, the bimodal-structured TBCs effectively improved the oxidation resistance of the Ti–6Al–4V substrate. The Ti–6Al–4V substrate with bimodal-structured TBCs only gained 0.51 times the mass gained by the bare Ti–6Al–4V after 100 h of isothermal oxidation. [ABSTRACT FROM AUTHOR]

Abstract In this study, flaky Fe 95 Si 1 B 2 P 0.5 Cu 1.5 powders with a particle size of 48–75 μm were compounded with graphene (GR) by high-energy ball milling to prepare GR/Fe 95 Si 1 B 2 P 0.5 Cu 1.5 composite powders. The electromagnetic parameters of GR/Fe 95 Si 1 B 2 P 0.5 Cu 1.5 composite powders in the frequency band of 0.3–8.5 GHz were determined by a vector network analyser. The influence of milling time and graphene content on the electromagnetic parameters of GR/Fe 95 Si 1 B 2 P 0.5 Cu 1.5 composite powders was studied. The results showed that with the increase of graphene content, magnetic permeability and dielectric constant increase simultaneously. The 1.0 wt% GR/Fe 95 Si 1 B 2 P 0.5 Cu 1.5 composite powders prepared by milling for 24 h exhibited the best absorbing property. In the frequency band of 0.3–8.5 GHz, for 1.0 wt% GR/Fe 95 Si 1 B 2 P 0.5 Cu 1.5 composite, the dielectric constant was 182.4–18.2, and the magnetic permeability was 7.3–1.0. The dielectric loss tangent was 3.40–6.60, the magnetic loss tangent was 0.48–3.46, and their sum was 5.28–8.60; therefore, 1.0 wt% GR/Fe 95 Si 1 B 2 P 0.5 Cu 1.5 composite exhibited excellent absorbing properties. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, the collapsing fracture of 60Si2Mn spring flat steels during cold-punching is analyzed by use of an optical microscope, a scanning electronic microscope, an optical stereomicroscopy, an energy dispersive spectrometer, an inductively coupled plasma-mass spectrometry, the hardness testers and a Charpy impact tester. The results show that the collapsing fracture of 60Si2Mn spring flat steels during cold-punching is due to the non- homogenization of microstructures and the nonmetallic inclusions. When the spring flats are cold-punched, the different deformation properties of the inclusions, the ferrites and the cementites initiated micro-cracks. The micro-cracks propagate along the interfaces of ferrites and cementites. The collapsing fracture is characteristic with transgranularity, cleavage and pearlites. The large space lamella pearlites with low strength are the main reason of the cleavage transcrystalline fracture. The prevention measurements are suggested. [Copyright &y& Elsevier]

Based on the study of microwave loss percolation effect of FeNi p /PP nanocomposites, the microwave healing technology of FeNi p /PP nanocomposites was proposed and its mechanism was studied. There is a unique microwave loss percolation characteristic between the microwave loss factor (tanδ) of FeNi p /PP nanocomposites and the content of FeNi powders (0–20 wt%), and the percolation area is the range of 2–10 wt%. The microwave healing technology can realize the self-healing property of the PP-based composites. When the composites received the microwave signal, the magnetic nanopowders generate heat effect to heat the resin matrix, which forms a mobile phase. The mobile phase, melted PP matrix with some magnetic nanopowders, moved toward the microcracks, thereby healing or reducing microcracks inside the composite. The optimum time for microwave treatment was 15 min. After microwave healing, the microcracks of the composites were closed, and the tensile strength of FeNi p /PP nanocomposites can be restored to 90% of that before damage. Capsule self-healing materials cannot provide effective crack healing due to the limited volume of healing agent transported by capsules. Moreover, the packaging technology of capsule is complex and the repeatability is poor. Hollow fibers networks can deliver a large number of healing agents to the injured area, but they are not suitable for multiple healing at specific locations, especially for low-level injury events that do not intersect hollow fibers or capsules[10]. The patch has good resistance to cyclic loading damage, strong corrosion resistance and good shape adaptability, but the matching and bonding force between patch and structural materials need to be specially considered. The healing model [11] focuses on the analysis and calculation of the activation mode of the healing mechanism, the interaction between the healing agent and the crack, and how to restore mechanical properties. It can only be used as an evaluation method. [ABSTRACT FROM AUTHOR]