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Achieving excellent strength-ductility synergy in twinned NiCoCr medium-entropy alloy via Al/Ta co-doping

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journal of Materials Science & Technology 2021年第28期87卷 184-195页

作者： D.D.Zhang H.Wang j.Y.Zhang H.Xue G.Liu j.Sun State Key Laboratory for Mechanical Behavior of Materials Xi’an Jiaotong UniversityXi’an710049PR China Science and Technology on Reactor Fuel and Materials Laboratory Nuclear Power Institute of ChinaChengdu610041PR China

Alloying is an effective strategy to tailor microstructure and mechanical properties of metallic materials to overcome the strength-ductility trade-off *** this work,we combined a novel alloy design principle,*** pronounced solid solution hardening(SSH)based on the misfit volumes engineering,and simultaneously,architecting the ductile matrix based on the valence electron concentrations(VEC)criterion,to fulfill an excellent strength-ductility synergy for the newly emerging high/medium-entropy alloys(HEAs/MEAs).Based on this strategy,Al/Ta co-doping within NiCoCr MEA leads to an efficient synthetic approach,that is minor Al/Ta co-doping not only renders significantly enhanced strength with notable SSH effect and ultrahigh strain-hardening capability,but also sharply refines grains and induces abnormal twinning behaviors of(NiCoCr)_(92)Al_(6)Ta_(2) *** with the partially twinned NiCoCr MEA,the yield strength(σy)and ultimate tensile strength(σUTS)of fully twinned Al/Ta-containing MEA were increased by~102%to~600 MPa and~35%to~1000 MPa,respectively,along with good ductility beyond 50%.Different from the NiCoCr MEA with deformation twins(DTs)/stacking faults(SFs)dominated plasticity,the extraordinary strain-hardening capability of the solute-hardened(NiCoCr)_(92)Al_(6)Ta_(2) MEA,deactivated deformation twinning,originates from the high density of dislocation walls,microbands and abundance of *** abnormal twinning behaviors,i.e.,prevalence of annealing twins(ATs)but absence of DTs in(NiCoCr)_(92)Al_(6)Ta_(2) MEA,are explained in terms of the relaxation of grain boundaries(for ATs)and the twinning mechanism transition(for DTs),respectively.

关键词： Medium-entropy alloys Mechanical properties Solid solution hardening Twinning behavior Strength-ductility synergy

Brain Injury Biomechanics and Abusive Head Trauma

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journal of Forensic Science and Medicine 2018年第2期4卷 91-100页

作者： Rudy j Castellani Carl j Schmidt Center for Neuropathology Western Michigan University Homer Stryker MD School of MedicineKalamazoo Department of Pathology University of Maryland School of MedicineBaltimoreMDUSA Department of Pathology University of MichiganAnn ArborMichigan

Contemporary biomechanical theory of traumatic brain injury has its foundation in Holbourn’s thesis on shear strain and Ommaya’s primate experimentation demonstrating the role of rotation in a variety of lesions including subdural hematoma(SDH)and diffuse axonal *** human observations have since confirmed,for the most part,the early *** concerns regarding primate research,however,have prompted in vitro models,which in turn has led to challenges with respect to the correlation between in vitro observations and the clinical *** these challenges,medicolegal proceedings may call upon biomechanical engineers to reconstruct complex injury scenarios and offer opinions on the scientific plausibility of clinical disease states,such as SDH,hemorrhagic retinopathy,and cerebral edema,associated with hypothetical or proffered action sequences during the course of an unwitnessed *** is important to note,however,that in vitro models by their nature are low‑evidence quality studies that attempt to advance hypotheses but do not address cause and *** a whole,biomechanical models,as they pertain specifically to the brain and spine,are mathematically ***,endpoints of limited relevance are relied upon(e.g.,skull fracture thresholds),which predictably overestimate the in vivo risk of significant *** the increasing role of biomechanical engineering in the interpretation of fatal pediatric head trauma,a heightened awareness of the limitations warranted.

关键词： Abusive head trauma biomechanics brain injury impact subdural hematoma

Implementing the Node Based Smoothed Finite Element Method as User Element in Abaqus for Linear and Nonlinear Elasticity

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Computers, Materials & Continua 2019年第8期61卷 481-502页

作者： S.Kshrisagar A.Francis j.j.Yee S.Natarajan C.K.Lee Integrated Modelling and Simulation Lab Department of Mechanical EngineeringIndian Institute of Technology MadrasChennai600036India The Department of Architectural Engineering Dong-A UniversityS04-0302Engineering 237Nakdongdaero 550beon-gilSaha-guBusan49315Korea National Research Center for Disaster-free&Safe Ocean City Dong-A UniversityS04-0311-3Engineering 237Nakdong-daero 550beon-gilSaha-guBusan49315Korea

In this paper,the node based smoothed-strain Abaqus user element(UEL)in the framework of finite element method is *** basic idea behind of the node based smoothed finite element(NSFEM)is that finite element cells are divided into subcells and subcells construct the smoothing domain associated with each node of a finite element cell[Liu,Dai and Nguyen-Thoi(2007)].Therefore,the numerical integration is globally performed over smoothing *** is demonstrated that the proposed UEL retains all the advantages of the NSFEM,i.e.,upper bound solution,overly soft stiffness and free from locking in compressible and nearly-incompressible *** this work,the constant strain triangular(CST)elements are used to construct node based smoothing domains,since any complex two dimensional domains can be discretized using CST *** additional challenge is successfully addressed in this *** efficacy and robustness of the proposed work is obtained by several benchmark problems in both linear and nonlinear *** developed UEL and the associated files can be downloaded from https://***/nsundar/NSFEM.

关键词： Smoothed finite element method(SFEM) node based SFEM(NSFEM) linear and nonlinear elasticity Abaqus UEL(user elements) compressible and nearlyincompressible materials

3D Printing of Polylactic Acid Bioplastic–Carbon Fibres and Twisted Kevlar Composites Through Coextrusion Using Fused Deposition Modeling

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journal of Renewable Materials 2020年第12期8卷 1671-1680页

作者： j.Y.Tey W.H.Yeo Y.j.King W.O.Ding Department of Mechanical and Material Engineering Lee Kong Chian Faculty of Engineering and ScienceUniversiti Tunku Abdul RahmanJalan Sungai LongBandar Sungai LongCheras43000 KajangSelangorMalaysia

Polylactic acid(PLA)bioplastic is a common material used in Fused Deposition Modeling(FDM)3D *** is biodegradable and environmentally friendly biopolymer which made out of ***,it exhibits weak mechanical properties which reduced its usability as a functional prototype in a real-world *** the present study,two PLA composites are created through coextruded with 3K carbon fibres and twisted Kevlar string(as core fibre)to form a fibre reinforced parts(FRP).The mechanical strength of printed parts was examined using ASTM D638 standard with a strain rate of 1 mm/*** has been demonstrated that the FRPs coextruded with 3K carbon fibres had achieved significant improvement in Young’s modulus(+180.6%,9.205 GPa),ultimate tensile strength(+175.3%,103 MPa)and maximum tensile strain(+21.6%,1.833%).Although the Young’s modulus of Kevlar FRP was found to be similar to as compared to unreinforced PLA(~3.29 GPa),it has gained significant increment in terms of maximum tensile strain(+179.7%,104.64 MPa),and maximum tensile strain(+257%,5.384%).Thus,this study revealed two unique composite materials,in which the 3K carbon FRP can offer stiff and high strength structure while Kevlar FRP offers similar strength but at a higher elasticity.

关键词： 3D printing Kevlar fibre 3K carbon fibre coextruded reinforced plastic polylactic acid bioplastic

Evaluating the performance of nanostructured materials as lithium-ion battery electrodes

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Nano Research 2014年第1期7卷 1-62页

作者： Mark j. Armstrong Colm O'Dwyer William j. Macklin justin. D. Holmes Materials Chemistry & Analysis Group Department of Chemistry and the Tyndall National Institute University College Cork Cork Ireland Applied Nanoscience Group Department of Chemistry and the Tyndall National Institute University College Cork Cork Ireland Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN) Trinity College Dublin Dublin 2 Ireland Nexeon Limited Abingdon Oxfordshire UK.

The performance of the lithium-ion cell is heavily dependent on the ability of the host electrodes to accommodate and release Li＋ ions from the local structure. While the choice of electrode materials may define parameters such as cell potential and capacity, the process of intercalation may be physically limited by the rate of solid-state Li＋ diffusion. Increased diffusion rates in lithium-ion electrodes may be achieved through a reduction in the diffusion path, accomplished by a scaling of the respective electrode dimensions. In addition, some electrodes may undergo large volume changes associated with charging and discharging, the strain of which, may be better accommodated through nanostructuring. Failure of the host to accommodate such volume changes may lead to pulverisation of the local structure and a rapid loss of capacity. In this review article, we seek to highlight a number of significant gains in the development of nanostructured lithium-ion battery architectures （both anode and cathode）, as drivers of potential next-generation electrochemical energy storage devices.

关键词： lithium ion batteries nanostructuring anodes cathodes

Distinct dendritic α phase emerging on the surface of primary α phase in a compressed near-α titanium alloy

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journal of Materials Science & Technology 2018年第4期34卷 666-669页

作者： Z.Liu Z.B.Zhao j.R.Liu Q.j.Wang R.Yang Institute of Metal Research Chinese Academy of Sciences School of Materials Science and Engineering University of Science and Technology of China

The characteristic of the surface morphology of primary α phase was studied in a deformed near-α tita- nium alloy. Dendritic α phase emerged on the surfaces of primary α phase when the alloy was air-cooled in α ＋β phase field after deformation. The dendritic α grain has the same orientation with its original primary α grain. The formation of the dendritic α phase could be explained by interface instability in epi- taxial growth process of the primary α phase. The dislocations induced by deformation could facilitate the formation of dendritic α phase leading to the dendritic α phase and more obvious with the increase of strain. The growth of dendritic α phase was finally limited by the nucleation of second α phase with cooling.

关键词： Epitaxial growth Dendritic α phase Microstructure Interface instability Hot deformation

Endoscopic ultrasound-guided elastography in the nodal staging of oesophageal cancer

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World journal of Gastroenterology 2012年第9期18卷 889-895页

作者： Stuart Paterson Fraser Duthie Adrian j Stanley Department of Gastroenterology Forth Valley Royal Hospital Department of Pathology Glasgow Royal Infirmary Department of Gastroenterology Glasgow Royal Infirmary

AIM： To assess quantitative endoscopic ultrasound （EUS）- guided elastography in the nodal staging of oesophago- gastric cancers.METHODS： This was a single tertiary centre study as- sessing 50 patients with established oesophago-gastric cancer undergoing EUS-guided fine needle aspiration biopsy （FNAB） of lymph nodes between july 2007 and july 2009. EUS-guided elastography of lymph nodes was performed before EUS-FNAB. Standard EUS charac- teristics were also described. Cytological determination of whether a lymph node was malignant or benign was used as the gold standard for this study. Comparisons of elastography and standard EUS characteristics were made between the cytologically benign and malignant nodes. The main outcome measure was the accuracy of elastography in differentiating between benign and malignant lymph nodes in oesophageal cancers.

关键词： Endoscopic ultrasound Oesophageal cancerLymph nodes Elastography Tumour staging

Multiple ballistic impacts on 2024-T4 aluminum alloy by spheres:Experiments and modelling

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journal of Materials Science & Technology 2021年第35期94卷 164-174页

作者： j.C.Cheng S.P.Zhao D.Fan H.W.Chai S.j.Ye C.Li S.N.Luo Y.Cai j.Y.Huang School of Materials Science and Engineering Southwest Jiaotong UniversityChengduSichuanP.R.China The Peac Institute of Multiscale Sciences ChengduSichuanP.R.China

Multiple ballistic impacts are carried out on a 2024-T4 aluminum alloy by spherical steel projectiles(5-mm diameter)at~400 m s^(-1),to investigate its dynamic deformation and *** ballistic impact process is captured with high-speed *** samples are characterized with optical imaging,three-dimensional laser scanning,microhardness testing and electron backscatter *** increasing number of impacts,crater diameter increases slightly,but crater depth and crater volume increase significantly,and strain accumulation leads to microhardness increase *** parameters all follow power-law relations with the number of ***-like deformation bands and macroscopic deformation twins are produced by impact as a result of spontaneous dislocation self-pinning under high strain rate,large shear *** multiple impacts,shear strain accumulation in the arc-shaped region of the crater induces deformation twinning when it exceeds a critical value(~1.1-1.6).It is highly possible that the deformation twins are related to deformation bands,since they both share one set of the{111}pole with the initial matrix grain.A finite element method model is optimized to reproduce experimental observations and interpret deformation mechanisms.

关键词： 2024Al-T4 alloy Multiple impacts Twin-like deformation band Deformation twinning Finite element method

Nanoscale strained-Si MOSFET physics and modeling approaches:a review

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journal of Semiconductors 2010年第10期31卷 19-23页

作者： Amit Chaudhry j.N.Roy Garima joshi University Institute of Engineering and Technology Panjab University Solar Semiconductor Private Limited

An attempt has been made to give a detailed review of strained silicon technology. Various device models have been studied that consider the effect of strain on the devices, and comparisons have been drawn. A review of some modeling issues in strained silicon technology has also been outlined. The review indicates that this technology is very much required in nanoscale MOSFETs due to its several potential benefits, and there is a strong need for an analytical model which describes the complete physics of the strain technology.

关键词： mobility SiGe strained-Si technology CAD