High-hardness iron-based alloy coatings are extensively utilized in aerospace, automotive, and industrial equipment due to their exceptional wear resistance and long service life. Laser cladding has emerged as one of the primary techniques for fabricating these coatings, owing to its rapid cooling and dense microstructure characteristics. However, the production of high-hardness iron-based alloy coatings via laser cladding continues to face numerous challenges, particularly when controlling the morphology, quantity, and distribution of the reinforcing phases, which can lead to cracking during processing and service, thus compromising their usability. The cracks of the cladding layer will be suppressed through good microstructure design and control, resulting in a wide range of performance for high-hardness Fe-based alloy coatings. This paper reviews recent advancements in the design and control of the organization and structure of high-hardness iron-based alloy coatings from the perspectives of material composition, processing parameters, and external assistance techniques. It summarizes the properties and applications of various materials, including different alloying elements, ceramic particles, and rare earth oxides, while systematically discussing how processing parameters influence microstructure and performance. Additionally, the mechanisms by which external auxiliary energy fields affect the melt pool and solidified microstructure during laser cladding are elucidated. Finally, the future development directions of laser cladding technology for high-hardness iron-based coatings are anticipated, emphasizing the need for further quantification of the optimal coupling relationships among the gain effects of composite energy fields.

Plasmonic Fano resonance (FR) that contributes to multitudinous potential applications in subwavelength nanostructures can facilitate the realization of tunable wavelength selectivity for controlling light–matter interactions in metasurfaces. However, the plasmonic FR can be generated in metasurfaces with simple or complex geometries, and few of them can support flexible amplitude modulation and multiwavelength information transfer and processing. Here, we study the near‐infrared plasmonic FR in a hybrid metasurface composed of concentrically hybridized parabolic‐hole and circular‐ring‐aperture unit cells, which can induce polarization‐dependent dual‐wavelength passive plasmonic switching (PPS) and digital metasurface (DM). It is shown that the designable plasmonic FR can be realized by changing the geometric configurations of the unit cells. In particular, owing to the polarization‐dependent characteristic of FR, it is possible to fulfill a compact dual‐wavelength PPS with high ON/OFF ratios in the related optical communication bands. Moreover, such PPS that manipulates the amplitude response of the transmitted spectrum is an efficient way to reveal a 1‐bit DM, which can also be rationally extended to a 2‐bit DM or more. Our results suggest a pathway for studying polarization‐dependent PPS and programmable metasurface devices, yielding possibilities for subwavelength nanostructures in optical communication and information processing.

With the first-principle method, we studied the effects of the type and position of defects on the defect formation energy, electronic band structure, and electron mobility of the 4-layer hexagonal system silicon carbon (4H–SiC). The vacancy defect formation energy is smaller than the interstitial defect formation energy. The C vacancy defect formation energy is the smallest, while the Si interstitial defect formation energy is the largest. The defect formation energy is little affected by the defect position. The electronic band structure shows semi-metallic property due to the vacancy defect and the interstitial defect, and it shows a smaller bandgap due to the antisite defect. The electronic band structure changes little while the defect position changes. The electron mobility is reduced in varying degrees according to different defect types. The electron mobility changes little while the defect position changes.

The technology of the TiB₂/TiB cladding layer addresses the issue of the insufficient wear resistance of cup-shaped parts composed of titanium alloy materials. In order to eliminate the cracking problem of laser cladding TiB₂/Ti-based alloy, 30%TiB₂/Ti-based alloy gradient coating was prepared on the surface of titanium alloy by laser cladding in this study. The results revealed that the microstructure of the matrix and the cladding layer is metallurgically bonded. The microstructures of the cladding layer appear as rod-like and coarse-grained features on the surface, and fine needle-like and small-grained morphologies inside. The fine needle-like TiB precipitated in situ from the melt has a flat interface with Ti and exhibits a low degree of interfacial mismatch, while the interface between small particle-like TiB and Ti is wavy and has a high degree of interfacial mismatch. The gradual increase in the amount of TiB is present from the surface to the bottom of the cladding layer, while the amount of unmelted TiB₂ particles decreases. The chemical structure of the cladding layer is mainly presented as TiB₂, TiB and α-Ti phases. The maximum hardness of the cladding layer is 725 HV_0.2, where it is more than twice the hardness of the substrate. The fretting wear resistance of the cladding layer is better than that of the titanium alloy substrate under low loads (50 N–100 N), while a high load (more than 150 N) triggers a reverse outcome.

We show that the group-velocity-led optical event horizon (OEH) in optical fibers provides a convenient way to actively control the propagation property of higher-order solitons by a comparatively weak dispersive wave (DW) pulse. It has been found numerically that clean soliton breakup, a process by which a second-order soliton completely splits into a pair of constituent solitons with vastly different power proportions after interacting with the weak DW pulse, will occur while external DWs become polychromatic. The temporal separation between both constituent solitons can be controlled by adjusting the power of the external DW. The more energetic main soliton is advanced/trailed in time depending on the selected frequency of input DW pulse. We have developed an analytic formalism describing the external acting-force (AF) perturbation. These results provide a fundamental explanation and physical scaling of optical pulse evolution in optical fibers and can find applications in improved supercontinuum sources.

With large-scale molecular dynamics, we investigate displacement cascades in monocrystalline silicon with regard to the effects of temperature, strain, and primary knock-on atom energy on defect generation and evolution. With temperature increasing, both the thermal spike region and the peak defect count increase, while the effect of temperature on the surviving defect number is negligible. Nevertheless, higher temperature shows negative effect on clustering of vacancy. The effects of uniaxial strain on defect production and clustering is negligible, while its hydrostatic counterpart is evident. With the increment of hydrostatic strain, both the peak and surviving defect count increase (decrease) under tensile (compressive) hydrostatic loading. Meantime, tensile hydrostatic strain will promote defect clustering. More defects and larger defect clusters are produced at higher energy. Otherwise, interstitials are hard to form clusters under different conditions.