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SSRN 2023年

作者： Marian, Jaime McElfresh, Cameron Wang, Y. Morris Department of Materials Science and Engineering United States Department of Materials Science and Engineering University of California Los Angeles Los AngelesCA90095 United States Department of Mechanical and Aerospace Engineering University of California Los Angeles Los AngelesCA90095 United States

Laser-powder bed fusion additive manufacturing (LPBF-AM) of metals is rapidly becoming one of the most important materials processing pathways for next-generation metallic parts and components in a number of important applications. However, the large parametric space that characterizes laser-based LPBFAM makes it challenging to understand what are the variables controlling the microstructural and mechanical property outcomes. Sensitivity studies based on direct LPBFAM processing are costly and lengthy to conduct, and are subjected to the specifications and variability of each printer. Here we develop fast-throughput numerical approach that simulates the LPBF-AM process using a cellular automaton model for dynamic solidification and grain growth. This is accompanied by a polycrystal plasticity model that captures grain boundary strengthening due to complex grain geometry and furnishes the stress-strain curves of the resulting microstructures. Our approach connects the processing step with the mechanical testing step, thus capturing captures the effect of processing variables such as the laser power, laser spot size, scan speed, and hatch distance on the yield strength and tangent moduli of the processed materials. When applied to pure Cu and stainless 316L steel, we find that laser power and scan speed have the strongest influence on grain size in each material, respectively. © 2023, The Authors. All rights reserved.

关键词： Cellular automata

High-Porosity, Layered Iridium Oxide as an Efficient, Durable Anode Catalyst for Water Splitting

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CCS Chemistry 2025年第1期7卷 216-228页

作者： Zhoubing Xie Xiao Liang Zhenye Kang Yongcun Zou Xiyang Wang Yimin A.Wu Graham King Qi Liu Yalan Huang Xiao Zhao Hui Chen Xiaoxin Zou State Key Laboratory of Inorganic Synthesis and Preparative Chemistry College of ChemistryJilin UniversityChangchun 130012 State Key Laboratory of Marine Resource Utilization in South China Sea Hainan Provincial Key Lab of Fine ChemistrySchool of Chemical Engineering and TechnologyHainan UniversityHaikou 570228 Department of Mechanical and Mechatronics Engineering Waterloo Institute for NanotechnologyUniversity of WaterlooWaterlooOntario N2L 3G1 Canadian Light Source Saskatoon SK S7N 2V3 Department of Physics City University of Hong KongHong Kong 999077 School of Materials Science and Engineering Key Laboratory of Automobile Materials of MOEState Key Laboratory of Automotive Simulation and ControlElectron Microscopy CenterJilin UniversityChangchun 130012

Lowering iridium(Ir)loading without sacrificing activity and durability is critical to the future development of proton exchange membrane water electrolyzer(PEMWE).Here,we present the synthesis of iridate-derived,layered iridium oxide microparticles(dubbed p-L-IrO_(2))with a high open porosity of approximately 74%and their structural advantages for the fabrication of efficient,durable,low-Ir-loading anode catalytic layer in *** p-L-IrO_(2) material is synthesized by an easily scalable route involving acid treatment of alkali metal salt-templated iridates that form in mixed alkali metal nitrateshydroxides at low *** combination of high-porosity morphology and layered structure in the material preferentially exposes a high density of hydroxylated edge sites,which are catalytically active and stable to achieve the oxygen evolution reaction via a structurally hydroxyl group-participated adsorbate evolution *** material is further demonstrated to enable the fabrication of low-Ir-loading anode catalytic layers in PEMWE,which can afford excellent catalytic performance(2.7 A cm^(−2)@1.9 V@80℃;membrane:Nafion^(TM)N115)due to the simultaneous reduction of activation and mass transport losses and retention of catalytic activity for 2300 h at 1.0 A cm^(−2) current density.

关键词： electrocatalysis water splitting iridium porous materials PEM electrolyzer

Dual Mechanism for Transient Capacitance Anomaly in Improper Ferroelectrics

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Physical Review Letters 2024年第25期133卷 256801-256801页

作者： Xin Li Yu Yun Pratyush Buragohain Haidong Lu Arashdeep Singh Thind Donald A. Walko Detian Yang Rohan Mishra Alexei Gruverman Department of Physics and Astronomy University of Nebraska Lincoln Nebraska 68588 USA Institute of Materials Science and Engineering Washington University in St. Louis St. Louis Missouri USA Department of Mechanical Engineering and Materials Science Washington University in St. Louis St. Louis Missouri USA Advanced Photon Source Argonne National Laboratory Lemont Illinois 60439 USA Nebraska Center for Materials and Nanoscience University of Nebraska Lincoln Nebraska 68588 USA

Negative capacitance (NC) effects in ferroelectrics can potentially break fundamental limits of power dissipation known as “Boltzmann tyranny.” However, the origin of transient NC of ferroelectrics, which is attributed to two different mechanisms involving free-energy landscape and nucleation, is under intense debate. Here, we report the coexistence of transient NC and an S-shaped anomaly during the switching of ferroelectric hexagonal ferrites capacitor in an RC circuit. The early-stage NC arises from the nucleation process, while the late-stage S-shaped anomaly corresponds to a nascent NC associated with the free-energy landscape. The entire waveform can be reproduced using a hybrid model that simultaneously incorporates these two mechanisms. These results highlight the multivariable free-energy landscape of hexagonal ferrites that enables an abrupt change of the internal field and demonstrate that the two mechanisms are not mutually exclusive, resolving the long-standing debate. The behavior of the S-shaped anomaly also provides a pathway to extract parameters of free-energy landscape and switching dynamics.

关键词： Nucleation

Microhardness and Corrosion Properties of Two New Titanium Alloys for Medical Devices

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SSRN 2024年

作者： Jiménez-Marcos, Cristina Mirza-Rosca, Julia Claudia Baltatu, Madalina Vizureanu, Petrica Mechanical Engineering Department Las Palmas de Gran Canaria University Las Palmas de Gran Canaria35014 Spain Transilvania University of Brasov Materials Engineering and Welding Department Brasov500036 Romania Department of Technologies and Equipments for Materials Processing Faculty of Materials Science and Engineering Gheorghe Asachi Technical University of Iasi Iasi700050 Romania

Currently, metallic implants, especially titanium and its alloys, are common in orthopedic surgery. However, some of these alloys, such as Ti6Al4V or TiNi, release toxic ions. This has prompted research into new alloys such as Ti-Mo-Zr-Ta, which reduce toxicity and improve corrosion resistance. This study is focused on the characterization and comparison of the properties of the new TixMo15Ta7Zr (x = 15, 20) titanium alloys. This is achieved through the use of scanning electron microscopy, electrochemical tests and microhardness tests. The results demonstrated that both samples exhibited favorable biocompatibility and corrosion resistance, indicating their suitability for use in the human body. © 2024, The Authors. All rights reserved.

关键词： Titanium alloys

A Comprehensive Study on Macro/Microstructure, mechanical Properties and Wear Behavior of Ultra-Fine Grained Al/Cu/Sn/Ni Multi-Layered Composite Fabricated by Accumulative-Roll-Bonding (Arb) Process

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SSRN 2024年

作者： Mahdavian, Mehdi M. Khodabandeh, Alireza R. Jafarian, Hamid Reza Mirdamadi, Sh. Department of Materials Engineering Science and Research Branch Islamic Azad University Tehran Iran Department of Mechanical Engineering École de Technologie Supérieure MontrealQCH3C 1K3 Canada School of Metallurgy & Materials Engineering Iran University of Science and Technology Narmak Tehran16846-13114 Iran

In this study, Al/Cu/Sn/Ni multilayer composite (MLC) was processed by accumulative roll bonding (ARB) process up to 6 cycles. The results indicated that severe fragmentation was occurred at the Ni layer in the Al matrix during the sandwich cycle, whereas it was occurred at the Cu layer during the 2nd cycle. In contrast, the Sn layer was preserved its continuity in the Al matrix until the 6th cycle. The formation of the Al3Ni2 and AlCu intermetallic compounds during the 6th cycle was also detected by X-ray diffraction (XRD) analysis. The nucleation of the dynamic recrystallized (DRX) grains through continuous dynamic recrystallization (CDRX) and discontinuous dynamic recrystallization (DDRX) was begun in some parts of the Al matrix following the 3rd cycle. Furthermore, during the 6th cycle, in addition to DRXed grains, the normal grain growth (NGG) as well as slight abnormal grain growth (AGG) had been occurred in the Al matrix, creating the multiple grain size. The tensile strength of the MLC increased up to 188 MPa after 6 cycles. Also, the microhardness of the individual layers increased continuously until the final cycle. Wear results also showed that during the initial cycles, due to the low hardness of the MLC, wear mechanisms such as adhesive, delamination and abrasive were dominant and during the last cycles, due to the increase in hardness and the increase of the number of the interface of the layers, wear mechanisms such as delamination, fatigue and spalling were dominant. © 2024, The Authors. All rights reserved.

关键词： Binary alloys

Investigation of the Effects of Oyster Shell Powder Bio-Fillers on the mechanical Properties of Reinforced Epoxy Composites

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Investigation of the Effects of Oyster Shell Powder Bio-Fill...

science, engineering and Business for Sustainable Development Goals (SEB-SDG), International Conference on

作者： Newton I. Agbeboh Abon Adus Adeolu A. Adediran Isiaka O. Oladele Oluwasogo L. Ogundipe Dept. of Mechanical and Mechatronics Engineering Federal University Otuoke Bayelsa State Nigeria Dept. of Mechanical Engineering Landmark University Omu-Aran Kwara State Nigeria Dept. of Mechanical Science University of Johannesburg South Africa Dept. of Metallurgical and Materials Engineering Federal University of Technology Akure Ondo State Nigeria

ISBN: (数字)9798350358155

ISBN: (纸本)9798350358162

Oyster shells are majorly composed of large amounts of calcium with layers of viscoelastic proteins. However, due to their biodegradability, Oyster shells are regarded as waste materials. The shells can be combined with lightweight polymer matrices, like the widely used epoxy thermosetting polymer. This research seeks to utilize oyster shells as bio-fillers for reinforced epoxy composite manufacture. Oyster shell powder was, used as a reinforcement for an epoxy polymer matrix to create a new composite with superior mechanical properties. Oyster shell powders were used as natural fillers composites were developed using different ratios of the Epoxy resin (10%, 20%, and 30%) of oyster shell powder, employing the hand layup method. This was done to improve the hardness, tensile, and impact resistance properties of the epoxy composite. As a direct result of using the oyster shell powders as reinforcement materials infused within the epoxy polymer matrix. The results were critically analyzed and it was discovered that the addition of oyster shell powders led to the enhancement of the impact resistance of the developed composites, while the hardness and tensile strengths of the composites were slightly reduced compared to the control. The developed composites could be utilized as plastic-based ceiling boards for the construction industry.

关键词： Proteins Waste materials Insulation Powders Composite materials mechanical factors Polymers

Soft-lock drawing of super-aligned carbon nanotube bundles for nanometre electrical contacts (vol 17, pg 278, 2022)

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NATURE NANOTECHNOLOGY 2022年第3期17卷 331-331页

作者： Guo, Yunfan Shi, Enzheng Zhu, Jiadi Shen, Pin-Chun Wang, Jiangtao Lin, Yuxuan Mao, Yunwei Deng, Shibin Li, Baini Park, Ji-Hoon Lu, Ang-Yu Zhang, Shuchen Ji, Qingqing Li, Zhe Qiu, Chenguang Qiu, Song Li, Qingwen Dou, Letian Wu, Yue Zhang, Jin Palacios, Tomas Cao, Anyuan Kong, Jing Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology Cambridge MA USA Research Institute of Frontier Technology College of Micro-Nano Electronics Zhejiang University Hangzhou China Key Laboratory of 3D Micro/Nano Fabrication and Characterization of Zhejiang Province School of Engineering Westlake University Hangzhou China School of Materials Science and Engineering Peking University Beijing China Davidson School of Chemical Engineering Purdue University West Lafayette IN USA Taiwan Semiconductor Manufacturing Company (TSMC) Hsinchu Taiwan Department of Mechanical Engineering Massachusetts Institute of Technology Cambridge MA USA Department of Chemistry Purdue University West Lafayette IN USA College of Chemistry and Molecular Engineering Peking University Beijing China Department of Chemical and Biological Engineering Iowa State University Ames IA USA Key Laboratory for the Physics and Chemistry of Nanodevices and Department of Electronics Peking University Beijing China Division of Advanced Nano-Materials Suzhou Institute of Nano-Tech and Nano-Bionics Chinese Academy of Sciences Suzhou China

The assembly of single-walled carbon nanotubes (CNTs) into high-density horizontal arrays is strongly desired for practical applications, but challenges remain despite myriads of research efforts. Herein, we developed a non-destructive soft-lock drawing method to achieve ultraclean single-walled CNT arrays with a very high degree of alignment (angle standard deviation of ~0.03°). These arrays contained a large portion of nanometre-sized CNT bundles, yielding a high packing density (~400 µm−1) and high current carrying capacity (∼1.8 × 108 A cm−2). This alignment strategy can be generally extended to diverse substrates or sources of raw single-walled CNTs. Significantly, the assembled CNT bundles were used as nanometre electrical contacts of high-density monolayer molybdenum disulfide (MoS2) transistors, exhibiting high current density (~38 µA µm−1), low contact resistance (~1.6 kΩ µm), excellent device-to-device uniformity and highly reduced device areas (0.06 µm2 per device), demonstrating their potential for future electronic devices and advanced integration technologies.

关键词： Carbon nanotubes and fullerenes materials science general Nanotechnology Nanotechnology and Microengineering

Unusual Secondary Slip Activity at Room Temperature in VC Single Crystals

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SSRN 2024年

作者： Aleman, Angel Zaid, Hicham Tanaka, Koichi Yang, Jenn-Ming Kodambaka, Suneel Kindlund, Hanna Department of Mechanical and Aerospace Engineering University of California Los Angeles Los AngelesCA90095 United States Department of Materials Science and Engineering University of California Los Angeles Los AngelesCA90095 United States Department of Materials Science and Engineering Virginia Polytechnic Institute and State University BlacksburgVA24061 United States

Cubic transition-metal carbides are high-melting compounds with remarkable high-temperature mechanical properties but are generally considered to be brittle at low-temperatures. Here, we report on the activation of multiple slip systems and plasticity in 001, 110, and 111 oriented vanadium carbide (VC) single-crystals subjected to uniaxial compression at room-temperature. Using in situ scanning electron microscopy based mechanical testing, we observe plastic strains up to 21%, size-dependent yielding, and work hardening in VC(001) and VC(111). In comparison, VC(110) crystals are relatively brittle with limited localized plasticity. VC(111) crystals exhibit the highest yield strengths of up to ~23.0 GPa while VC(001) crystals are some of the softest with yield strengths as low as ~13 GPa. For loading along [110], we find that only the primary slip system, {111}, is active. In VC(001) and VC(111), we find the operation of two sets of slip systems, [{110} and {111}] and [{111} and {100}], respectively. Intriguingly, the estimated critical resolved shear stresses for all the three slip systems are nearly the same. Our results, which reveal orientation-dependent differences in the activity of the same slip system, provide new insights into plastic deformation in refractory compounds. © 2024, The Authors. All rights reserved.

关键词： Plasticity

High-throughput reaction engineering to assess the oxidation stability of MAX phases

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npj Computational materials 2021年第1期7卷 20-32页

作者： D.Sauceda P.Singh A.R.Falkowski Y.Chen T.Doung G.Vazquez M.Radovic R.Arroyave Department of Materials Science & Engineering Texas A&M UniversityCollege StationTX 77843USA Department of Mechanical Engineering Texas A&M UniversityCollege StationTX 77843USA Ames Laboratory US Department of EnergyIowa State UniversityAmesIA50011USA

The resistance to oxidizing environments exhibited by some Mn+1AXn(MAX)phases stems from the formation of stable and protective oxide layers at high operating *** MAX phases are hexagonally arranged layered nitrides or carbides with general formula M_(n+1)AX_(n),n=1,2,3,where M is early transition elements,A is A block elements,and X is C/*** attempts to model and assess oxide phase stability in these systems has been limited in scope due to higher computational *** address the issue,we developed a machine-learning driven high-throughput framework for the fast assessment of phase stability and oxygen reactivity of 211 chemistry MAX phase M_(2)*** proposed scheme combines a sure independence screening sparsifying operator-based machine-learning model in combination with grand-canonical linear programming to assess temperaturedependent Gibbs free energies,reaction products,and elemental chemical activity during the oxidation of MAX *** thermodynamic stability,and chemical activity of constituent elements of Ti_(2)AlC with respect to oxygen were fully assessed to understand the high-temperature oxidation *** predictions are in good agreement with oxidation experiments performed on Ti_(2)*** were also able to explain the metastability of Ti_(2)SiC,which could not be synthesized experimentally due to higher stability of competing *** generality of the proposed approach,we discuss the oxidation mechanism of Cr_(2)*** insights of oxidation behavior will enable more efficient design and accelerated discovery of MAX phases with maintained performance in oxidizing environments at high temperatures。

关键词： stability MAX maintained

On the computation of electrical conductivities of aqueous electrolyte solutions: Two surfaces one property

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arXiv

arXiv 2024年

作者： Blazquez, Samuel Abascal, Jose Lagerweij, Jelle Habibi, Parsa Dey, Poulumi Vlugt, Thijs Moultos, Othonas Vega, Carlos Dpto. Química Física I Fac. Ciencias Químicas Universidad Complutense de Madrid Madrid28040 Spain Engineering Thermodynamics Process and Energy Department Faculty of Mechanical Maritime and Materials Engineering Delft University of Technology Leeghwaterstraat 39 Delft2628CB Netherlands Department of Materials Science and Engineering Faculty of Mechanical Maritime and Materials Engineering Delft University of Technology Mekelweg 2 Delft2628CD Netherlands

In this work, we have computed electrical conductivities at ambient conditions of aqueous NaCl and KCl solutions by using the Einstein-Helfand equation. Common force fields (charge q =±1 e) do not reproduce the experimental values of electrical conductivities, viscosities and diffusion coefficients. Recently, we proposed the idea of using different charges to describe the Potential Energy Surface (PES) and the Dipole Moment Surface (DMS). In this work, we implement this concept. The equilibrium trajectories required to evaluate electrical conductivities (within linear response theory) were obtained by using scaled charges (with the value q =±0.75 e) to describe the PES. The potential parameters were those of the Madrid-Transport force field, which describe accurately viscosities and diffusion coefficients of these ionic solutions. However, integer charges were used to compute the conductivities (thus describing the DMS). The basic idea is that although the scaled charge describes the ion-water interaction better, the integer charge reflects the value of the charge that is transported due to the electric field. The agreement obtained with experiments is excellent, as for the first time electrical conductivities (and the other transport properties) of NaCl and KCl electrolyte solutions are described with high accuracy for the whole concentration range up to their solubility limit. Finally, we propose an easy way to obtain a rough estimate of the actual electrical conductivity of the potential model under consideration using the approximate Nernst-Einstein equation, which neglects correlations between different ions. © 2024, CC BY-NC-ND.

关键词： Sodium chloride