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SSRN 2023年

作者： Lang, Qiang Zhang, Zhaodong Wang, Zeli Song, Gang Shehryar Khan, Muhammad Liu, Liming School of Materials Science and Engineering Dalian University of Technology Dalian116000 China Department of Mechanical & Mechatronics Engineering University of Waterloo 200 University Avenue West WaterlooONN2L3G1 Canada

Laser-arc hybrid direct lap welding offers an effective method for achieving high-performance welding of magnesium (Mg) alloys to steel. In this study, we optimized the mechanical properties of dissimilarly joined Mg and steel by controlling the offset of the laser heat source which directly affected the power delivered to the workpiece. We analyzed the variation of wetting angle and the mechanism of strengthening and tensile failure of the joints, with the results showing that under ideal processing conditions, the tensile strength of the direct lap welded joint without filler wire or any interlayers reached 295.7 N/mm, which is approximately 80% of the Mg alloy’s nominal strength – an improvement that has not been previously reported in the literature. The laser improved the wettability of the joint and the laser keyhole played a critical role in pinning the weld seam, increasing the area of the interfacial reaction layer, and transferring the location of the crack source to strengthen the joint performance. © 2023, The Authors. All rights reserved.

关键词： Magnesium alloys

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3d Printable Ca(Oh)2-Based Geopolymer Concrete with Steel Fiber Reinforcement

SSRN

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SSRN 2024年

作者： Mortada, Youssef Hammoud, Ahmad Masoud, Laith Wyrzykowski, Mateusz Sirtoli, Davide Lura, Pietro Mansoor, Bilal Masad, Eyad Department of Materials Science and Engineering Texas A&M University 575 Ross Street College StationTX77843 United States Mechanical Engineering Program Texas A&M University at Qatar P. O. Box 23874 Doha Qatar J. Mike Walker’66 Department of Mechanical Engineering Texas A&M University College StationTX77843 United States Concrete and Asphalt Laboratory Empa DübendorfCH-8600 Switzerland Institute for Building Materials ETH Zurich ZurichCH-8092 Switzerland Zachary Department of Civil and Environmental Engineering Texas A&M University College StationTX77843 United States

This study explores the impact of varying steel fiber percentages (0%, 0.8%, 1.0%, and 1.2% of the binder by volume) on the mechanical properties of geopolymer concrete (GPC). Initial investigations on the GPC matrix involved characterization of mechanical properties through tests of compressive, flexural, and tensile strengths, which were conducted across all fiber percentages. The best results were obtained at 1.2% fiber content, with a more than doubling of the 28-day tensile strength and a 16% increase of the flexural strength relative to the material without steel fibers. The compressive strength was not affected and remained at around 40 MPa. The interlayer bond strength increased by 20%, and both the dynamic and the static elastic moduli improved, indicating an improvement in structural integrity and capacity. The early-age cracking risk was assessed by measurements of autogenous shrinkage, of self-induced stresses measured with the Dual Ring Tests, and compressive basic creep on the mixture with 1.2% fiber content. These tests demonstrated a significant reduction in shrinkage and slight decrease in self-induced stresses. Microstructure analysis using X-ray microtomography, SEM, and ASTM C642 tests further confirmed the improved structural integrity of the steel fiber-reinforced concrete. The optimal fiber content of 1.2% of the binder not only strengthens the geopolymer matrix but also improves its long-term stability and durability, making it a viable reinforcement choice for additive manufacturing and construction applications. © 2024, The Authors. All rights reserved.

关键词： Steel fibers

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Bovine Serum or Chicken Egg Albumin: Does the Source of Protein Affect Mg Degradation?

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SSRN 2023年

作者： Imani, Amin Shahsavari, Mohammadali Raman, R.K. Singh Asselin, Edouard Department of Materials Engineering Faculty of Applied Science The University of British Columbia VancouverBCV6T 1Z4 Canada Department of Mechanical and Aerospace Engineering Monash University ClaytonVIC3800 Australia Department of Chemical Engineering Monash University ClaytonVIC3800 Australia

We measure the simulated biodegradation of commercially pure (CP) Mg in a saline environment containing albumin from bovine or chicken egg sources. Albumins from different sources have different effects on the biodegradation behavior of Mg. Therefore, the source of albumin should be considered for in vitro assessment of Mg-based biomaterials. © 2023, The Authors. All rights reserved.

关键词： Proteins

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Si3N4 Manifold Microchannels Cooling System for High Heat Flux Electronic Applications

Si3N4 Manifold Microchannels Cooling System for High Heat Fl...

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Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITHERM)

作者： Yue Qiu Chirag Kharangate Jennifer Carter James McGuffin-Cawley Department of Mechanical and Aerospace Engineering Case Western Reserve University Cleveland Ohio USA Department of Materials Science and Engineering Case Western Reserve University Cleveland Ohio USA

ISBN: (数字)9781665485036

ISBN: (纸本)9781665485043

The increasing energy dissipation in more compact and powerful electronic systems has led to extreme high heat fluxes which call for more effective thermal management solutions. [1] One innovative cooling strategy to meet the dissipation demand is two-phase cooling utilizing manifold-microchannels, it can achieve high heat transfer while maintaining low pressure drops in comparison to conventional two-phase microchannels. For electronics cooling in extreme environment, Si3N4-based ceramic is an ideal substrate due to its high thermal conductivity, low elastic modulus, and sufficient strength and toughness. In this study, a reduced order thermal-fluidic analysis of Si3N4 manifold-microchannel for two-phase boiling flows is conducted for dissipating up to 1 kW of heat from a 1 cm 2 heated area on a compact Si3N4 sample. The effect of manifold-microchannel geometry parameters on pressure drop and heat resistance are investigated. The performances of different type of working fluids are also compared, including R134a, R1234yf, R1234ze(E), R245fa, and R1233zd, FC72, and HFE7100. The proposed manifold-microchannels with R134a as the working fluid can achieve low pressure drop ~20 kPa and low thermal resistance ~0.06 K/W with a mass flow rate requirement of 9~ 13 g/s for a heat flux of 1 kW/cm 2 .

关键词： Manifolds Geometry Fluids Cooling Thermal resistance Thermomechanical processes Heat transfer

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Multistate Control of Nonlinear Photocurrents in Optoferroelectrics via phase manipulation of light field

arXiv

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arXiv 2025年

作者： Kazempour, Ali Sisakht, Esmaeil Taghizadeh Okyay, Mahmut Sait Jiang, Xiao Sato, Shunsuke Park, Noejung Department of physics Payame Noor University PO BOX Tehran119395-3697 Iran Department of Physics Ulsan National Institute of Science and Technology Ulsan689-798 Korea Republic of Materials Science and Engineering Program Department of Chemical and Environmental Engineering University of California-Riverside RiversideCA92521 United States Center for Computational Sciences University of Tsukuba Tsukuba305-8577 Japan

Ultrafast optical control of ferroelectricity based on short and intense light can be utilized to achieve accurate manipulations of ferroelectric materials, which may pave a basis for future breakthrough in nonvolatile memories. Here, we demonstrate that phase manipulation of electric field in the strong field sub-cycle regime induces a nonlinear injection current, efficiently coupling with the topology of band structure and enabling dynamic reversal of both current and polarization. Our time-dependent first-principles calculations reveal that tuning the phase of linearly or circularly polarized light through time-varying chirp, or constant carrier envelop phases within sub-laser-cycle dynamics effectively breaks the time-reversal symmetry, allowing the control over current and electronic polarization reversal over multi-ferroelectric states. Our time- and momentum-resolved transverse current analysis reveal the significance of Berry curvature higher order poles in the apparent association between the odd (even) orders of Berry curvature multipoles to odd (even) pseudo-harmonics in driving polarization dynamics reversal. We suggest that these phase manipulations of short pulse waveform may lead to unprecedented accurate control of nonlinear photocurrents and polarization states, which facilitate the development of precise ultrafast opto-ferroelectric devices. © 2025, CC BY.

关键词： Ferroelectricity

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Effects of Various Proportions Tib2p-Ticp Reinforced Al-Cu-Mg Composites in High-Temperature mechanical Properties and Sliding Wear Behaviors

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SSRN 2024年

作者： Zhong, Xinmiao Li, Qing-Yuan Meng, Meng Yang, Hong-Yu Qiu, Feng Jiang, Qichuan Duan, Xiang-Zheng Key Laboratory of Automobile Materials Ministry of Education Department of Materials Science and Engineering Jilin University Renmin Street NO. 5988 Jilin Province Changchun130025 China School of Mechanical and Aerospace Engineering Jilin University Renmin Street NO. 5988 Jilin Province Changchun130025 China State Key Laboratory of Automotive Simulation and Control China

Synergistic reinforcement of dual-phase particles with different sizes was always considered superior to single-phase reinforcement in composites, but there were few studies to investigate the role of each part in enhancing properties. In this work, 40 vol.% (TiB2p-TiCp)/Al-Cu-Mg composites with different proportions of TiB2p and TiCp (3:1, 2:1, 1:1, 1:2 and 1:3), were fabricated by the combustion synthesis to contrast the strengthening effect of dual-phase particles from the interface stability and the characteristics of dual-phase particles. Calculated by first principle, TiB2 (3.12 J/m2) presented better interfacial stability with Al matrix than TiC (1.61 J/m2). Under the circumstance of the same volume fraction, the composites with a higher proportion of TiB2p usually show higher yield and maximum compressive strength and effectively prevent crack growth of composites. However, excess submicron sized TiB2p tends to produce cracks at the hexagon edge when the loads were applied and formed crack loops delaminating materials. When the TiB2p/TiCp proportion was 1:1, plasticity and strength were beneficially balanced at the elevated temperature. Otherwise, the composite with TiB2: TiC=3:1 possessed the best wear resistance (coefficient of friction: 0.22) at a sliding velocity of 0.32 mm/s, 30N load) among other composites ([[EQUATION]],[[EQUATION]],[[EQUATION]], and [[EQUATION]]) at 473 K, which reduced 45%, 64%, 73% and 86%, respectively. The main wear mechanism was abrasive wear when the TiB2 proportion was dominant. Submicron sized TiB2p with better interface bonding can keep the rigidity of the composites to resist the plastic flow, while TiC nanoparticles are easier to be extracted during the wear process. © 2024, The Authors. All rights reserved.

关键词： Ductile fracture

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Grain incompatibility determines the local structure of amorphous grain boundary complexions

arXiv

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arXiv 2022年

作者： Garg, Pulkit Rupert, Timothy J. Department of Materials Science and Engineering University of California IrvineCA92697 United States Department of Mechanical and Aerospace Engineering University of California IrvineCA92697 United States

Amorphous grain boundary complexions lack long-range crystalline order but are not featureless, as distinct gradients in structural short-range order have been reported through their thickness. In this work, we test the hypothesis that the distribution of short-range order is determined by the confining crystals using atomistic simulations of both Cu-Zr bicrystals and a random polycrystal. Voronoi polyhedra with structures similar to that of perfect face-centered cubic serve as signatures of high structural order and are only found at the amorphous-crystalline transition regions. The density of the ordered structural motifs within a specific amorphous-crystalline transition region is found to not be directly determined by the orientation and symmetry of the grain which touches it, but rather by the incompatibility between the two confining grains. Ordered polyhedra density is found to be inversely related to grain incompatibility, meaning that large incompatibilities between the confining crystals lead to less order in the amorphous-crystalline transition region. The finding that the entire grain-film-grain system must be considered to understand local structure unequivocally demonstrates that amorphous complexions are not simply a collection of independent phases which happen to nucleate at a grain boundary. Rather, an amorphous grain boundary complexion is a single entity that finds a local equilibrium configuration. Copyright © 2022, The Authors. All rights reserved.

关键词： Grain boundaries

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Temperature and composition dependent screw dislocation mobility in austenitic stainless steels from large-scale molecular dynamics

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npj Computational materials 2020年第1期6卷 176-185页

作者： Kevin Chu Michael E.Foster Ryan B.Sills Xiaowang Zhou Ting Zhu David L.McDowell School of Materials Science and Engineering Georgia Institute of Technology AtlantaAtlantaGA 30332USA Sandia National Laboratories LivermoreCA 94550USA Department of Materials Science and Engineering Rutgers UniversityPiscatawayNJ 08854USA Woodruff School of Mechanical Engineering Georgia Institute of TechnologyAtlantaGA 30332USA

Extensive molecular dynamics simulations are performed to determine screw dislocation mobility in austenitic Fe_(0.7)NixCr_(0.3-x) stainless steels as a function of temperature ranging from 100 to 1300 K,resolved shear stress from 30 to 140 MPa,and Ni composition from 0.0 to 30.0 at%.These mobility data are fitted to a linear mobility law with a nonzero stress offset,referred to as the threshold *** find that both the linear drag coefficient and the threshold stress increase with Ni *** drag coefficient increases with temperature,whereas the threshold stress decreases with *** on these calculations,we determine fitting functions for the linear solute drag coefficient as a function of temperature and *** mobility laws determined in this study may serve to inform dislocation dynamics simulations pertinent to dislocation network evolution at elevated temperatures for a wide composition range of austenitic stainless steels.

关键词： austenitic dislocation dynamics

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Ultrastable Shear-Jammed Granular Material

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Physical Review X 2022年第3期12卷 031021-031021页

作者： Yiqiu Zhao (赵逸秋) Yuchen Zhao (赵雨辰) Dong Wang (王东) Hu Zheng (郑虎) Bulbul Chakraborty Joshua E. S. Socolar Department of Physics Duke University Durham North Carolina 27708 USA Department of Physics The Hong Kong University of Science and Technology Hong Kong SAR China School of Mechanical and Aerospace Engineering Nanyang Technological University 639798 Singapore Department of Mechanical Engineering and Materials Science Yale University New Haven Connecticut 06520 USA Department of Geotechnical Engineering College of Civil Engineering Tongji University Shanghai 200092 China Martin Fisher School of Physics Brandeis University Waltham Massachusetts 02454 USA

Dry granular materials, such as sand, gravel, pills, or agricultural grains, can become rigid when compressed or sheared. Under isotropic compression, the material reaches a certain jamming density and then resists further compression. Shear jamming occurs when resistance to shear emerges in a system at a density lower than the jamming density. Although shear jamming is prevalent in frictional granular materials, their stability properties are not well described by standard elasticity theory and thus call for experimental characterization. We report on experimental observations of changes in the mechanical properties of a shear-jammed granular material subjected to small-amplitude, quasistatic cyclic shear. We study a layer of plastic disks confined to a shear cell, using photoelasticimetry to measure all interparticle vector forces. For sufficiently small cyclic shear amplitudes and large enough initial shear, the material evolves to an unexpected “ultrastable” state in which all the particle positions and interparticle contact forces remain unchanged after each complete shear cycle for thousands of cycles. The stress response of these states to small imposed shear is nearly elastic, in contrast to the original shear-jammed state.

关键词： Collective behavior Dynamical phase transitions Elasticity Fatigue Granular materials Jamming mechanical deformation Rheology

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Comparison of CMAS corrosion and sintering induced microstructural characteristics of APS thermal barrier coatings

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Journal of materials science & Technology 2019年第3期35卷 440-447页

作者： Yiyou Wu Hua Luo Canying Cai Yanguo Wang Yichun Zhou Li Yang Guangwen Zhou School of Materials Science and Engineering Xiangtan University Key Laboratory of Low Dimensional Materials & Application Technology of Ministry of Education Xiangtan University Department of Mechanical Engineering & Materials Science and Engineering Program State University of New York at Binghamton

The microstructural features of high-temperature sintered and CaO-MgO-Al_2O_3-SiO_2(CMAS) corroded air plasma sprayed Y_2O_3 stabilized ZrO_2(YSZ) thermal barrier coatings(TBCs) under the thermal gradient condition were comparatively studied. As-sprayed YSZ has a lamellar structure and the lamellae are composed of closely aligned columnar crystals. The sintered and the CMAS corroded YSZ coatings maintain the t'-ZrO_2 phase as the as-sprayed YSZ coating. The sintered YSZ remains the lamellar structure with reduced interlamellar gaps and grains coarsening. After the CMAS corrosion, the top layer of the YSZ coating keeps its lamellar structure consisting of some columnar grains with the CMAS infiltration into the intergrain gaps and the formation of striped Zr_2Y_2 O_7. The typical lamellar structure transforms into more equiaxed grains in the middle and bottom layers of the ceramic coating along with significant infiltration of amorphous CMAS and anorthite formation in the bottom layer owing to the high contents of Ca and Al.

关键词： YSZ thermal barrier coating APS CMAS corrosion Anorthite

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