Search

The effect of rare earth Y on precipitates and textures of the grain-oriented silicon steels, the composition, morphology, size, quantity of inclusions and texture evolution of hot-rolled and cold-rolled oriented silicon steel containing rare earth Y were studied using transmission electron microscopy, field emission scanning electron microscope, and electron backscatter diffraction. The results show that there are mainly spherical or ellipsoidal Y2O2S precipitates in the Y bearing silicon steel. Rare earth treatment effectively improves the precipitates’ morphology and restrains the precipitation of the long-strip MnS in the hot-rolled plate. Meanwhile, the microstructure is more uniform, and the recrystallized grains on the surface and the fiber structure in the central layer are larger after hot rolling compared with Y-free steel. Furthermore, with the addition of rare earth Y, the unfavorable brass texture and rotational cube texture in the hot-rolled plate are reduced. Meanwhile, the number of shear bands is increased and the strength of the favorable {111} 〈112〉 texture is improved in the cold-rolled plate, which helps develop the Goss texture during the annealing process.

Bright‐band defects frequently occur on as‐cast strips in the twin‐roll strip‐casting process, particularly at low‐casting speeds, with intervals of ≈200 mm. Additionally, the cast‐rolling force also exhibits minor fluctuations. With increasing casting speeds, the spacing between bright‐band defects widens, and the severity of these defects diminishes. When the casting speed reaches a certain threshold, defects almost entirely disappear. Detailed analysis of the underlying causes of this phenomenon is essential for effectively preventing defect formation. In this study, the numerical simulation method is employed to analyze casting rolls' thermal deformation and the melt pool's solidification behavior, based on the production site equipment and process conditions. The causes of defects in as‐cast strips are thoroughly analyzed based on simulation results, in conjunction with variations in the cast‐rolling force. In this study, it is demonstrated that the thermal deformation of casting rolls and the position of the solidification endpoints collectively contribute to the fluctuations in cast‐rolling force and are the primary causes of bright‐band defects. Fundamental principles for preventing defects are provided based on actual on‐site production. Furthermore, simulation results contribute to establishing a theoretical basis for selecting process parameters and controlling cast‐rolling force during production. [ABSTRACT FROM AUTHOR]

Diverse domain patterns significantly influence the nonlinear electromechanical behaviors of ferroelectric nanomaterials, with polarization switching under strong electric fields being inherently a frequency-dependent phenomenon. Nevertheless, research in this area remains limited. In this study, we present a phase-field investigation of frequency-dependent electromechanical dynamics of a polycrystalline BaTiO3 nanofilm with a core-shell structure, subjected to applied frequencies ranging from 1 to 80 kHz. Our findings elucidate the microstructural mechanisms underlying the electromechanical behaviors observed in these materials. The effect of the grain size and the strains effect are also taken into account. Hysteresis and butterfly loops exhibit a marked change in shape as the frequency changes. We discuss the underlying domain-switching dynamics as a basis for evaluating such frequency-dependent properties. In addition, we examine the scaling behaviors of the dynamic hysteresis and the influence of grain boundaries on the domain structure. We can also observe from hysteresis loops that the remnant polarization and coercive field significantly diminish when grain sizes decrease from 60 to 5 nm. A smaller grain size of the nanofilm yields a larger percentage of the dielectric grain boundary, which "dilutes" the overall ferroelectricity of the film. A vortex domain structure is more likely to form at low frequency and a small grain size. [ABSTRACT FROM AUTHOR]

In order to study the effect of cold-rolling deformation and rare earth Y on the microstructure and texture of 3.0% Si-oriented silicon steel, the microstructure and texture of cold-rolled oriented silicon steel with 60, 72, and 86% deformation are analyzed using electron backscatter diffraction and image analysis software. The experimental results show that the deformation band becomes narrower and the distribution of shear bands becomes denser with increasing cold-rolling deformation. Compared to the Y-free steel, cold-rolled sheet containing rare earth Y has greater shear bands. The pinning effect of rare earth Y hinders the dislocation movement, which leads to the increase of kernel average misorientation value and shear bands. With the increase of cold-rolling deformation, the texture concentrates on α and λ. This is mainly due to the change from {100} 〈001〉 to {001} 〈110〉, intensifying λ texture, and the change from {111} 〈112〉 to {111} 〈110〉, thus strengthening the α texture. The texture strength of cold-rolled sheets can be decreased by rare earth Y. But the γ texture strength in cold-rolled sheets containing Y is significantly higher than in those without Y. The γ texture strength can reach up to 7.3, and the strong points are mainly {111} 〈112〉. This is because the number of inclusions in steel increases with the addition of rare earth Y. In the process of grain nucleation, the {111} oriented grains nucleate heterogeneously on the inclusions. It forms a large number of {111} oriented grains and improves the γ texture strength.

Organic molecules with redox centers have emerged as promising cathode materials for rechargeable magnesium batteries (RMBs), owing to their rich natural resources, high capacity, and sustainability. However, their application has been severely plagued by their high solubility and poor conductivity. Herein, we propose a dual-pronged strategy to mitigate these issues faced by phenazine (PZ) electrodes by employing the ionic liquid (IL) N-butyl-N-methyl-piperidinium bis((trifluoromethyl)sulfonyl)imide (PP14TFSI) as an electrolyte additive and coating a graphene/polyvinyl pyrrolidone (graphene@PVP) composite layer onto a commercial glass fiber (GF) separator. The addition of highly polar PP14TFSI with high ion conductivity and high viscosity into the electrolyte can mitigate the dissolution of the organic electrode, and catalyze the dissociation of Mg–Cl in large MgxCly2x−y clusters to expedite reaction kinetics. Furthermore, the graphene@PVP layer which served as a barrier against soluble species and an upper current collector, can further retard the shuttle phenomenon and promote the reutilization of PZ molecules. Besides, the presence of graphene@PVP can build an internal electric field, thus facilitating charge transfer. As anticipated, the assembled Mg//PZ cells exhibited a high discharge capacity of 230 mA h g−1 at 0.1 A g−1 and a commendable rate capability of 97.5 mA h g−1 at 5.0 A g−1 with an exceptionally low capacity decay rate of 0.00164% per cycle for 17 700 cycles. This work has provided a new route for the advancement of high-performance metal–organic batteries through the synergistic implementation of electrolyte engineering and separator modification. [ABSTRACT FROM AUTHOR]