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As a critical material for high-temperature components of aero-engines, the mechanical properties of Ti65 alloy, subjected to high-temperature and long-term thermal exposure, directly affect its service safety. The room-temperature tensile properties of the Ti65 alloy after thermal exposure to temperatures ranging from 450 °C to 650 °C for 100 h were investigated. The results indicate that as the thermal exposure temperature increases, the strength of Ti65 alloy initially increases and then decreases, while ductility exhibits a decreasing trend. The strength of the thermally exposed alloy positively correlates with the size and content of the α2 phase. The ductility of the thermally exposed alloy is comprehensively influenced by the surface oxidation behavior, α2 phase, and silicides. After the prolonged thermal exposure, stress concentration at the crack tips within the oxide layer was enhanced with the increased thickness of the surface TiO2 oxide layer, leading to premature fracture due to reduced alloy ductility. Furthermore, the α2 phase in the matrix promotes the planar slip of dislocations, while silicides at the α/β phase boundaries hinder dislocation motion, causing dislocation pile-ups. Both behaviors facilitate crack nucleation and deteriorate alloy ductility. [ABSTRACT FROM AUTHOR]

High‐rate dissolution process of Ti–48Al–2Cr–2Nb alloy in electrochemical machining exhibits strong nonlinear dynamic characteristics, but the quantitative relationship between these nonlinear characteristics and surface topography, as well as the electro‐dissolution mechanism, is unknown. Therefore, the fractal and recursive features of dissolution behavior and quantitative characterization of the dissolved surface topography were investigated. Additionally, an electro‐dissolution mechanism model in electrochemical machining process was presented. Applying a higher potential of 11 V can enhance the stability of the electrochemical system, resulting in a smoother and uniform surface. The saturation correlation dimension, surface roughness, and integral area of lacunarity initially decrease before increasing with higher electrolytic pressure, while laminarity and determinism show an initial increase followed by a decrease. These five characteristic parameters reach their optimal values at an electrolyte pressure of 0.4 MPa, indicating that achieving a stable and deterministic electrochemical system is crucial for obtaining a uniform smooth surface. These nonlinear dynamic characteristic parameters can be considered as in‐situ monitoring parameters for surface quality in ECM. The anodic dissolution process comprises three stages: initial passive film dissolution and breakdown, rapid dissolving with surface coarsening, and stable dissolving with polishing. [ABSTRACT FROM AUTHOR]

In order to reconstruct discontinuous signal with the least error by using finite information, the concept of all-phase data processing and the conventional Fourier approximation were combined. By utilizing the coefficients acquired by discrete Fourier transforming the samples of signal and the high harmonic information, all-phase Fourier reconstruction was formed. Theoretical deduction and experimental research show that the waveform reconstructed by all-phase Fourier method has less error than those constructed by conventional continuous Fourier integral approximation and the discrete Fourier reconstruction.

It is widely recognized that the intrinsic dipole in two-dimensional (2D) photocatalysts promotes hydrogen production during water splitting. Herein, we wonder whether the intrinsic dipole plays a negative role in water splitting. In this work, we make a comparative study of the structural, electronic, and photocatalytic properties of Janus B2XY (X, Y = S, Se, Te) and F-BNBN-H monolayers using first principles. Our theoretical results reveal that both B2XY and F-BNBN-H monolayers exhibit spatially separated conduction band minimum (CBM) and valence band maximum (VBM), as well as vacuum level differences at the opposite surfaces due to the intrinsic dipole. The F-BNBN-H monolayer has excellent redox ability for water splitting, because its CBM is located at the surface with a lower vacuum level and its VBM is distributed on the opposite surface possessing a higher vacuum level. By sharp contrast, B2XY monolayers have limited or vanishing redox ability, because their CBM is located at the surface with a higher vacuum level and their VBM is distributed on the opposite surface with a lower vacuum level. This work emphasizes the negative role of vacuum level differences of photocatalysts caused by the intrinsic dipole in water splitting. [ABSTRACT FROM AUTHOR]

For a fiber Bragg grating (FBG) surface-bonded to a substrate subjected to tension, the FBG reflective wavelength spectrum measured using an optical spectrum analyzer is different in either the location of the center wavelength or the spectral shape from that calculated using the transfer matrix (T-matrix) method. We show that the difference in the two wavelength spectra is caused by the adhesive layer used to bond the FBG to the substrate and a birefringence effect within the strained FBG. In the former case, the adhesive reduces the strain transferred from the substrate to the FBG and, therefore, causes the T-matrix method to overestimate the shift in the center wavelength. In the latter case, a birefringence effect is induced within the FBG because only the lower part of the FBG is bonded to the stressed substrate. As a result, both the peak power and the full width at half-maximum of the experimental spectrum differ from that predicted by the T-matrix method, in which the effects of birefringence are ignored. However, it is shown that when the strain transmission loss and birefringence effect are compensated using a strain transmission correction factor and a modified T-matrix formulation based on a discretized value of the refractive index, respectively, a good agreement is obtained between the calculated spectrum and that measured experimentally. [c] 2010 Optical Society of America OCIS codes: 060.3735, 060.3738, 060.2300, 060.2310, 060.2370.