摘要 ：

Aluminoborate glass, recognized for its remarkable crack resistance, presents significant potential as a cover material for portable electronic devices. Nevertheless, its relatively low hardness has been a limiting factor. This study synthesized a series of 11 Li2O-30 Al2O3-(55-x) B2O3-2 TiO2-2 P2O5-xCaO (wt%), with x varying from 0 to 10, employing the melt-cast method. The resultant glass-ceramics were produced via heat treatment at 590 degrees C for 2 h, followed by a systematic examination of their structural and mechanical properties. The investigation demonstrated that an increase in CaO content diminishes crystallization and induces a morphological transition in the crystalline phases from granular and short rod-like structures to lath-like formations, which subsequently impacts the coordination environment of Al and B atoms. With a CaO content of 2 %, the GC2 sample precipitated Li(Al7B4O17) and Li2AlB5O10 phases, achieving a compressive strength (CR) value of 15.0 N, a hardness of 7.51 GPa, and a fracture toughness of 1.50 MPa m0.5. This glass-ceramic exhibited optimal scratch resistance and visible light transmittance exceeding 85 %, underscoring its considerable promise for application as smartphone cover glass due to its impressive overall damage resistance.

关键词 ：

Transmittance Calcium oxide Glass-ceramics Aluminoborate glass Damage resistance

引用：

复制并粘贴一种已设定好的引用格式，或利用其中一个链接导入到文献管理软件中。

摘要 ：

Assembly construction is extensively employed in bridge construction due to its ability to accelerate construction and improve quality. To speed the recovery of bridges after major earthquakes, this study proposes an assembled connection for precast piers and footings based on assembly construction. The precast piers are connected to the footings using ultra-high-performance concrete (UHPC) post-cast cupped sockets. Two specimens are tested with a 1:4 scale, namely, the cast-in-place (CIP) specimen and, the UHPC cupped socket pier specimen. Finite element models (FEM) of a continuous girder bridge with cupped socket connections are developed and verified by experimental results. The seismic fragility analysis is conducted to investigate the difference between the cupped socket connection and the CIP connection. The experimental results showed that the plastic hinge was formed on the precast piers and there was little damage to the UHPC sockets. The results of FEA indicate that UHPC cupped socket piers have slightly higher seismic fragility than the seismic fragility of cast-in-place piers. Then, some methods were proposed to reduce the seismic fragility of UHPC cupped socket piers, and their availability was confirmed by comparing them with the seismic fragility of CIP piers. Finally, an example bridge with this connection is introduced to illustrate replacing prefabricated piers after an earthquake.

关键词 ：

Piers-footing connection Seismic fragility analysis Quasi-static testing UHPC Assembly construction

引用：

复制并粘贴一种已设定好的引用格式，或利用其中一个链接导入到文献管理软件中。

摘要 ：

A wet connection for prefabricated slabs using Ultra-High-Performance Concrete (UHPC) was proposed and experimentally investigated. Influence of parameters such as the lap length of dowel rebar, the groove key size and the arrangement of post-placed rebar in grooves were comparatively explored. Four tensile specimens and eight flexural specimens were designed and tested. The crack development, failure mode, load-deformation characteristics, strains and bearing capacity were observed and analyzed. The results indicated that the lap length of dowel rebar significantly influenced the failure mode. Dowel rebar with insufficient lap length in postcast UHPC connection exhibited rebar pulling-out failure, and lap length of 12 times diameter of the dowel rebar could achieve mechanical performance equivalent to cast-in-situ construction. Based on analysis of the test results, the prediction for tensile capacity of UHPC connection was recommended based on existing prediction formula for bonding stress of rebar in concrete, and the theoretical predicting formulas for flexural bearing capacity and deflection of prefabricated slabs having different dowel rebar lap lengths in UHPC connection were proposed, which showed good agreement with test results.

关键词 ：

Wet connection Tensile and flexural performances Prefabricated slabs UHPC

引用：

复制并粘贴一种已设定好的引用格式，或利用其中一个链接导入到文献管理软件中。

摘要 ：

In addition to the three well-known Ag-related precipitates (, X' and Z) in the Al-Cu-Mg-Ag alloys, Ag can also be involved in the formation of the as-cast second phases. However, the effect of Ag addition in Al-Cu-Mg-Ag alloys has not been completely studied and even the structure of the as-cast Agcontaining phases is still controversial. By employing the focused ion beam (FIB) combined with transmission electron microscopy (TEM) techniques and density functional theory (DFT) calculations, the formation mechanisms of the Ag-containing phases in the as-cast Al-Cu-Mg-Ag alloys have been investigated. The Ag-containing phases are a series of hexagonal C14-type Laves phases with continuously varying Ag concentrations, described as (Alx Cuy Ag1-x-y)(2) Mg. Moreover, the specific occupancy sites of the atoms in (Alx Cuy Ag1-x-y)(2) Mg were determined. The formation of the (Alx Cuy Ag1-x-y )2 Mg can be attributed to the stronger Ag-induced aggregation of solute atoms in the initial stage and the establishment of strong Ag-X (X = Al, Mg and Ag) bonding in the Ag-containing phases. Furthermore, our experiments have revealed the solidification sequence of Al-Cu-Mg-Ag alloys, and pointed out that (Alx Cu-y Ag1-x-y)(2) Mg is formed at a lower temperature (493.9 degrees C) through the reaction L Al-2 CuMg + (Alx Cu-y Ag1-x-y)(2) Mg. The study could have positive implications for refinement of the Al-Cu-Mg-Ag quaternary phase diagram and promote the composition-property design of novel aluminum alloys based on (Alx Cuy Ag1-x-y)(2) Mg in the future. (c) 2023 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

关键词 ：

Al-Cu-Mg-Ag alloys Laves phases Formation mechanisms HAADF-STEM First -principles calculation

引用：

复制并粘贴一种已设定好的引用格式，或利用其中一个链接导入到文献管理软件中。

摘要 ：

Due to the light absorption and scattering in waterbodies, acquired underwater images frequently suffer from color cast, blur, low contrast, noise, etc., which seriously degrade the image quality and affect their subsequent applications. Therefore, it is necessary to propose a reliable and practical underwater image quality assessment (IQA) model that can faithfully evaluate underwater image quality. To this end, in this article, we establish a novel quality assessment model for underwater images by in-depth analysis and characterization of multiple image properties. Specifically, we propose characterizing the image luminance, color cast, sharpness, contrast, fog density and noise to comprehensively describe the image quality to evaluate the underwater image quality more accurately. Dedicated features are elaborately investigated to characterize those quality-aware image properties. After feature extraction, we employ support vector regression (SVR) to integrate all the quality-aware features and regress them onto the underwater image quality score. Extensive tests performed on standard underwater image quality databases demonstrate the superior prediction performance of the proposed underwater IQA model to state-of-the-art congeneric quality assessment models.

关键词 ：

Underwater image objective metric Image color analysis Colored noise Predictive models no-reference (NR) Visualization image quality assessment (IQA) Feature extraction Image quality statistical modeling Indexes

引用：

复制并粘贴一种已设定好的引用格式，或利用其中一个链接导入到文献管理软件中。

摘要 ：

The precast composite reinforced concrete wall with the advantages of fewer joints, superior impermeability and rapid construction provides an efficient and environmental friendly alternative in the construction of underground utility tunnels in the last few years. To investigate the seismic performance of precast concrete composite walls of utility tunnels with grouting-sleeve connection under out-ofplane loads, a series of quasi-static cyclic tests were performed on the full-scale sidewall specimens with different axial compression ratios in this study. The experimental results including the failure modes, crack distributions, and the influence of different connections on the out-of-plane seismic performance of precast concrete composite wall were carefully examined and compared with those from the cyclic tests of the cast-in-place sidewalls of the utility tunnel. The test results show that the seismic performance of the precast concrete composite sidewall specimen, such as the hysteresis curves, the ultimate bearing capacity, stiffness degradation pattern and the ductility ratio, is basically the same as that of the cast-in-place specimen, indicating that the seismic performance of the prefabricated structure is equivalent to that of the cast-in-place structure. Moreover, the grouting-sleeves of the joints can effectively transfer the reinforcement stress until the failure of the precast concrete composite sidewall specimens, which exhibits excellent out-of-plane ductility and serviceability.

关键词 ：

Seismic performance Precast concrete composite walls Grouting sleeve Cyclic response Failure mechanism

引用：

复制并粘贴一种已设定好的引用格式，或利用其中一个链接导入到文献管理软件中。

摘要 ：

The socket connection method is widely used in precast column, particularly in seismic regions. However, reducing the socket-depth to lower costs may lead to shear failure in the socketed part of the columns. To address this issue and achieve cost objectives, a new approach combines shallow sockets with corrugated pipes for column-footing joints. Comparative tests were conducted to investigate failure in columns with socketcorrugated pipe connections (SCPC), shallow sockets (SSC), and cast-in-place (CIP). Furthermore, finite element models were employed to validate the experimental and simplified model results. The findings suggest potential shear failure in shallow socket connections, which can be mitigated by using the combined socketcorrugated pipe method that alters force transmission paths. As the axial load ratio increases, both the ultimate lateral load capacity of the specimen and the local stresses at the column base increase. In addition, the ultimate lateral load capacity of the column and the stress of the connection reinforcement are increased by increasing the strength of the longitudinal reinforcement, consequently amplifying the extent of joint area damage. Finally, a simplified strut-and-tie model of the SCPC, validated against numerical and experimental data, accurately represents force paths, ultimate lateral load capacity and failure modes in socket joints.

关键词 ：

Socket-corrugated pipe combination Prefabricated assembly column Strut-and-tie model connection Force transmission path Numerical analysis

引用：

复制并粘贴一种已设定好的引用格式，或利用其中一个链接导入到文献管理软件中。

摘要 ：

The corrosive wear resistance of copper-bearing HHCCI was tested through experiments and HRTEM, combined with first-principles calculations to study the atomic structure, interface fracture work, thermodynamic stability, electronic structure and bonding structure of six Fe3Cr4C3(01 1 0)/gamma-Fe(101) interface models with different termination methods. The HRTEM results show that the interface formed by (01 1 0) of M7C3-type carbide and (101) of the austenite matrix is a coherent interface. The first principles calculation results show that the interface formed by the Fe3Cr4C3(01 1 0)-Cr termination model and the gamma- Fe (101)-2 termination model has the highest interface bonding strength. The Fe-end/7Fe-2 interface model is the most stable. Both the interfacial chemical energy and the interfacial elastic energy will affect the overall thermodynamic stability of the Fe3Cr4C3(01 1 0)/gamma-Fe (101) interface. The fracture work of Fe3Cr4C3(01 1 0) and gamma- Fe (101) is greater than the corresponding interface adhesion work. Moreover, the fracture work on each terminal end of M7C3 along the (01 1 0) surface is higher than that on each terminal end of gamma- Fe along the (101) surface. The failure of HHCCI during corrosive wear may mainly occur in the interface area or the side close to the gamma- Fe matrix. The chemical bonds in the Fe-end/7Fe interface are mainly Fe-Fe metal bonds, Fe-Cr metal bonds and some Fe-C polar covalent bonds. The chemical bonds in the Cr-end/7Fe interface are mainly Cr-Fe metal bonds and some Cr-C polar covalent bonds. The chemical bonds in the C-end/7Fe interface are mainly composed of Cr-Fe metal bonds, C-Fe polar covalent bonds and part of C-Cr polar covalent bonds, as a result, each interface exhibits different corrosive wear resistance potentials.

关键词 ：

Hypereutectic high chromium cast iron First principles calculation Corrosive wear resistance Interface

引用：

复制并粘贴一种已设定好的引用格式，或利用其中一个链接导入到文献管理软件中。

摘要 ：

The extreme high-speed laser material deposition (EHLA) process has the potential to enable additive manufacturing for mass production by overcoming the limitations of slow scanning speed in conventional laser material deposition (LMD) processes. Thermal features are the key factors to link process and properties. A sound understanding of process-thermal-property relationships is essential for performance control and process optimization of a deposited component. In this study, we studied the thermal characteristics within a single layer and among layers for continuous processing using the numerical method, and reveal the mechanism of microstructure and hardness changes of AISI 4140 material formed by EHLA and LMD processes through the analysis of thermal properties and temperature history results. The grain size and hardness evolution for both processes during single-layer cladding and continuous forming processes were investigated. The results revealed that the grain refinement effect in continuous LMD processing is stronger than that in EHLA process (from 30.0 mu m for single layer to 3.2 mu m for multi layers vs. from 18.6 mu m for single layer to 2.2 mu m for multi layers). Similar hardness values were obtained by LMD and EHLA processes, with mean values of 511 HV and 472 HV, respectively. The yield and tensile strengths of EHLA were superior to the conventional cast material, but inferior to those of the conventional material quenched and tempered at lower temperatures. The enhanced tensile results of EHLA process were found similar to those prepared through conventional method with quench and tempering at 600 degrees C.

关键词 ：

Mechanical properties Microstructure AISI 4140 Extreme high-speed laser material deposition Intrinsic heat treatment

引用：

复制并粘贴一种已设定好的引用格式，或利用其中一个链接导入到文献管理软件中。

摘要 ：

Developing high-performance metallic materials with high yield strength and excellent ductility is important for various applications, such as automobiles, power plants, and aerospace industries. However, conventional alloys typically exhibit a trade-off between strength and ductility, making it difficult to develop materials that are both strong and ductile. In this study, we report that a cast Co-Cr-Fe-Ni-Al alloy can achieve a high room temperature yield strength of up to 500 MPa, which is twice that of conventional high-entropy alloys (HEAs) with face- centered cubic structures, with a tensile strain of 29 %. After thermomechanical treatment, the alloy exhibits even better synergy of strength and ductility, with a yield strength of 900 MPa and 30 % elongation. These exceptional mechanical properties are conferred by a multiscale hierarchical heterostructure, which was introduced through careful control of the alloy composition using a negative enthalpy alloy design strategy. The heterostructure ranges from the micrometer to sub-micrometer and nanometer scales. This multiscale hierarchical structure acts as a continuous impediment to dislocation motion, greatly increasing strength, and facilitating hetero-deformation induced hardening via strain partitioning, resulting in sustained ultrahigh strain hardening. Importantly, multiscale hierarchical heterostructures facilitate coordinated plastic deformation and multiple plastic deformation mechanisms, and stress concentration relieving, and play important roles in improving ductility. This work reveals the effect of different types (and scales) of heterogeneities on the deformation mechanism of HEAs and opens new perspectives for constructing heterostructures, which serve as a new design approach for high strength and excellent ductility by using a negative enthalpy alloy design strategy.

关键词 ：

Multiscale hierarchical heterostructure Strength and ductility Negative enthalpy alloy Dislocation Strain hardening

引用：

复制并粘贴一种已设定好的引用格式，或利用其中一个链接导入到文献管理软件中。