Search

The addition of WC particles has the potential to improve the properties of 18Ni300 alloy, but the effect of heat treatment on the microstructure and mechanical properties of 18Ni300 matrix composites needs to be further investigated. In this work, WC-reinforced 18Ni300 composites were fabricated using laser powder bed fusion (LPBF). The composites were made into solutions at 846 °C for 51 min, followed by aging at 388 °C for 300 min. The microstructural evolution and compressive properties of the composites before and after heat treatment were systematically studied. The results indicate that the microstructures of the composites consist of heterogeneous cellular and fine columnar grains. As the WC content increases, the primary phase in the LPBF-formed samples gradually shifts from α-Fe martensite to γ-Fe austenite. After heat treatment, the primary phase transforms to α-Fe with only a small residual amount of γ-Fe. The microstructure becomes more uniform, featuring a significant reduction in grain size. Many precipitated phases can be found in the intergranular, accompanied by an increase in the thickness of diffusion layers. The WC content in the composite material is positively correlated with its hardness and compressive strength. As the WC reinforcement content increases from 5% to 20%, the yield strength and compressive strength of the LPBF-formed composites increase to 1042.5 MPa and 2900.7 MPa, respectively, while the compressive elongation decreases from 64% to 43%. After heat treatment, the yield strength of the composites significantly increases to 2356.8 MPa, with a slight increase in the compressive strength to 2939.7 MPa. However, the elongation decreases from 32.5% to 22%. [ABSTRACT FROM AUTHOR]

We propose and investigate a fiber-optic sensor of As2Se3 chalcogenide (ChG) microfiber laterally adhered on the hollow-core fiber (HCF) end face. HCF is fused with a single-mode fiber to form Fabry–Perot interferometer (FPI) between single-mode fiber (SMF) end face and ChG microfiber. ChG microfiber is ultra-sensitive to the small perturbations in the surroundings, because of its high refractive index and small Young's modulus. Furthermore, relative to traditional fiber-optic FPI comprised by thin film, our proposed FPI with thin-diameter ChG microfiber could respond to mechanical vibrations over a broad range of frequencies. Based on finite-element simulation, ChG microfiber has ultra-broadband dynamic frequency response, up to several hundreds of megahertz accompanied by a very small response strength decay, in comparison to the frequency response of ChG film which is typically less than 30 MHz. ChG microfiber-based FPI is also used in the static refractometric sensing with sensitivity of 1563 nm/RIU. Such a novel fiber-optic sensor offers excellent potential for the nondestructive detection and advanced biomedical sensing. [ABSTRACT FROM AUTHOR]