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Effect of processing parameters on formability, microstructure, and micro-hardness of a novel laser additive manufactured Ti-6.38Al-3.87V-2.43Mo alloy

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China Foundry 2022年第2期19卷 158-168页

作者： Tian-yu Liu zhi-hao zhu Shuang Zhang Xiao-hua Min Chuang Dong School of Materials Science and Engineering Dalian University of TechnologyDalian 116024LiaoningChina School of Materials Science and Engineering Dalian Jiaotong UniversityDalian 116028LiaoningChina

A novel Ti-6.38Al-3.87V-2.43Mo alloy was designed with a cluster formula of 12[Al-Ti12](V0.75Mo0.25Ti2)+4[Al-Ti12](Al3)by replacing Ti with Mo/V on the basis of the Ti-Al congruent alloy.The effects of laser power and scanning speed on the molten pool size,surface roughness,relative density,microstructure,and micro-hardness of single-track and bulk Ti-6.38Al-3.87V-2.43Mo samples prepared via laser additive manufacturing(LAM)were investigated.The results show that processing parameters significantly affect the formability,microstructure,and micro-hardness of the alloy.With decreasing laser power from 1,900 W to 1,000 W,the relative density is decreased from 99.86%to 90.91%due to the increase of lack-of-fusion;however,with increasing scanning speed,the relative density does not change significantly,but exceeds 99%.In particular,Ti-6.38Al-3.87V-2.43Mo samples of single-track and bulk exhibit a good formability under an input laser power of 1,900 W and a scanning speed of 8 mm·s_(-1),and display the lowest surface roughness(Ra=13.33μm)and the highest relative density(99.86%).Besides,the microstructure of LAM Ti-6.38Al-3.87V-2.43Mo alloy coarsens with increasing laser power or decreasing scanning speed due to the greater input energy reducing the cooling rate.The coarsening of the microstructure decreases the microhardness of the alloy.

关键词： laser additive manufacturing composition design cluster-plus-glue-atom model microstructure properties

A novel Ti-5.55Al-6.70Zr-1.50V-0.70Mo-3.41Nb-0.21Si alloy designed using cluster-plus-glue-atom model for laser additive manufacturing

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中国铸造:英文版 2023年第5期20卷 414-422页

作者： Tian-yu Liu Yan-chun Lou Shuang Zhang zhi-hao zhu Jun Zhao Shi-bing Liu Kun Shi Ning Zhao National Key Laboratory of Advanced Casting Technologies Shenyang Research Institute of Foundry Co.Ltd.CAMShenyang 110022China School of Materials Science and Engineering Beihang UniversityBeijing 100191China School of Materials Science and Engineering Dalian Jiaotong UniversityDalian 116028LiaoningChina School of Materials Science and Engineering Dalian University of TechnologyDalian 116024LiaoningChina

A novel Ti-5.55Al-6.70Zr-1.50V-0.70Mo-3.41Nb-0.21Si alloy was designed using the cluster formula approach(cluster-plus-glue-atom model)and prepared by laser melting deposition(LMD).Its composition formula 12[Al-Ti_(12)](AlTi_(2))+5[Al_(0.8)Si_(0.2)-Ti_(12)Zr_(2)](V_(0.8)Mo_(0.2)Nb_(1)Ti)features an enhancedβ-Ti via co-alloying of Zr,V,Mo,Nb and Si.The experimental results show that the cluster formula ofαandβphases in the novel alloy are respectivelyα-[Al-Ti_(11.5)Zr_(0.5)](Al_(1)Ti_(2))andβ-[Al_(0.8)Si_(0.2)-Ti_(13.2)Zr_(0.8)](V_(1)Mo_(0.4)Nb_(1.6)),both containing Zr elements.The fitted composition via the α andβphase cluster formulas has little difference with the actual alloy composition,suggesting that the validity of cluster-plus-glue-atom model in the alloy composition design.After hot isostatic pressing(HIP),both the Ti-6Al-4V and the novel alloy by LMD are characterized by prior-βcolumnar grains,while the typicaltexture disappears.Compared with Ti-6Al-4V,Ti-5.55Al-6.70Zr-1.50V-0.70Mo-3.41Nb-0.21Si alloy exhibits a combination of higher strength(1,056 MPa)and higher ductility(14%)at room temperature and higher strength(580 MPa)at 550℃ after HIP,and can potentially serves as LMD materials.

关键词： additive manufacturing laser melting deposition novel titanium alloy composition design cluster-plus-glue-atom model

Shearing-force-driven delamination of waste residue into oxidatively stable MXene composites for high-performance Si anode

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Rare Metals 2023年第7期42卷 2226-2237页

作者： Peng Liu zhi-hao zhu Wen Zhang Jia-Yi Liu Zhong Su Xin-Hua Liu Shi-Chun Yang Chao Lai School of Chemistry and Materials Science Jiangsu Normal UniversityXuzhou221116China School of Transportation Science and Engineering Beihang UniversityBeijing100191China

The low yield of MXene is normally related to the delaminating step,contributing to the key technical challenges in moving toward industrial applications.Here,a shearing-force-driven strategy is proposed for re-exfoliating waste MXene residue to prepare oxidatively stable MXene composites in a low-cost manner,where the strong shear stress in the assisted solvent,such as carbon nanotubes(CNTs),chitosan(CS),and polyacrylamide(PAM)aqueous solutions,acts on the surface of MXene(Ti_(3)C_(2)T_(x))through coordination between hydroxyl and Ti atoms,resulting in a rapid and efficient exfoliation of waste Ti_(3)C_(2)T_(x)residue under stirring.Furthermore,this formed coordinate bond helps to stabilize the low-valent Ti atoms on the surface of MXene,thereby enhancing the oxidative stability of Ti_(3)C_(2)T_(x).Besides,the CNT@MXene composite is selected to construct a free-standing membrane to encapsulate Si nanoparticles,achieving a high and reversible capacity after 50 cycles.This work supports the concept of valorizing waste and adopts a fluid shear forceassisted method to re-exfoliate waste residues,which greatly reduces the cost of processing and improves the chemical stability of MXene.More importantly,this work has uncovered a new direction for the commercialization of MXene composites and has significantly improved the realworld applications of MXene-based materials.

关键词： Waste residue Shear stress MXene composites Oxidatively stable Si anode

Microstructure, Tensile Properties and Work Hardening Behavior of an Extruded Mg–Zn–Ca–Mn Magnesium Alloy

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Acta Metallurgica Sinica(English Letters) 2020年第7期33卷 922-936页

作者： Kai-Bo Nie zhi-hao zhu Paul Munroe Kun-Kun Deng Jun-Gang Han College of Materials Science and Engineering Taiyuan University of TechnologyTaiyuan 030024China School of Materials Science and Engineering UNSW AustraliaKensingtonNSW 2052Australia

A new Mg-2.2 wt% Zn alloy containing 1.8 wt% Ca and 0.5 wt% Mn has been developed and subjected to extrusion under different extrusion parameters.The finest(~0.48 μm) recrystallized grain structures,containing both nano-sized MgZn2 precipitates and α-Mn nanoparticles,were obtained in the alloy extruded at 270℃/0.01 mm s-1.In this alloy,the deformed coarse-grain region possessed a much stronger texture intensity(~32.49 mud) relative to the recrystallized fine-grain region(~13.99 mud).A positive work hardening rate in the third stage of work hardening curve was also evident in the alloy extruded at 270℃,which was related to the sharp basal texture and which provided insufficient active slip systems.The high work hardening rate in the fourth stage contributed to the high ductility extruded at 270℃/1 mm s-1.This alloy exhibited a weak texture,and the examination of fracture surface revealed highly dimpled surfaces.The optimum tensile strength was achieved in the alloy extruded at 270℃/0.01 mm s-1,and the yield strength,ultimate tensile strength and elongation to failure were^364.1 MPa,~394.5 MPa and^7.2%,respectively.Fine grain strengthening from the recrystallized fine-grain region played the greatest role in the strength increment of this alloy compared with Orowan strengthening and dislocation strengthening in the deformed coarse-grain regions.

关键词： alloy grain strengthening

Design for Ti-Al-V-Mo-Nb alloys for laser additive manufacturing based on a cluster model and on their microstructure and properties

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China Foundry 2021年第4期18卷 424-432页

In this study,α+βTi-Al-V-Mo-Nb alloys with the addition of multiple elements that are suitable for laser additive manufacturing(LAM)were designed according to a Ti-6Al-4V cluster formula.This formula can be expressed as 12[Al-Ti12](AlTi2)+5[Al-Ti14]((Mo,V,Nb)2Ti),in which Mo and Nb were added into the alloys partially instead of V to give alloys with nominal compositions of Ti-6.01Al-3.13V-1.43Nb,Ti-5.97Al-2.33V-2.93Mo,and Ti-5.97Al-2.33V-2.20Mo-0.71Nb(wt.%).The microstructures and mechanical properties of the as-deposited and heat-treated samples prepared via LAM were examined.The sizes of theβcolumnar grains andαlaths in the Nb-containing samples are found to be larger than those of the Ti-6Al-4V alloy,whereas Mo-or Mo/Nb-added alloys contain finer grains.It indicates that Nb gives rise to coarsenedβcolumnar grains andαlaths,while Mo significantly refines them.Furthermore,the single addition of Nb improves the elongation,whereas the single addition of Mo enhances the strength of the alloys.The simultaneous addition of Mo/Nb significantly improves the comprehensive mechanical properties of the alloys,leading to the best properties with an ultimate tensile strength of 1,070 MPa,a yield strength of 1,004 MPa,an elongation of 9%,and micro-hardness of 355 HV.The fracture modes of all the alloys are ductile-brittle mixed fracture.

关键词： titanium alloy laser additive manufacturing cluster-plus-glue-atom model composition design microstructure mechanical properties

Research progress in Asia on methods of processing laser-induced breakdown spectroscopy data

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Frontiers of physics 2016年第5期11卷 137-149页

作者： Yang-Min Guo Lian-Bo Guo Jia-Ming Li Hong-Di Liu zhi-hao zhu Xiang-You Li Yong-Feng Lu Xiao-Yan Zeng Wuhan National Laboratory for Optoelectronics Huazhong University of Science and Technology (HUST) Wuhan 430074 China

Laser-induced breakdown spectroscopy （LIBS） has attracted much attention in terms of both scientific research and industrial application. An important branch of LIBS research in Asia, the development of data processing methods for LIBS, is reviewed. First, the basic principle of LIBS and the characteristics of spectral data are briefly introduced. Next, two aspects of research on and problems with data processing methods are described： i） the basic principles of data preprocessing methods are elaborated in detail on the basis of the characteristics of spectral data; ii） the performance of data analysis methods in qualitative and quantitative analysis of LIBS is described. Finally, a direction for future development of data processing methods for LIBS is also proposed.

关键词： laser-induced breakdown spectroscopy data preprocessing data analysis

Intermittent Theta Burst Stimulation Attenuates Cognitive Deficits and Alzheimer’s Disease-Type Pathologies via ISCA1-Mediated Mitochondrial Modulation in APP/PS1 Mice

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Neuroscience Bulletin 2024年第2期40卷 182-200页

作者： Yang zhu hao Huang zhi Chen Yong Tao Ling-Yi Liao Shi-hao Gao Yan-Jiang Wang Chang-Yue Gao Department of Rehabilitation Medicine Daping HospitalArmy Medical UniversityChongqing 400042China Department of Neurology and Center for Clinical Neuroscience Daping HospitalArmy Medical UniversityChongqing 400042China Department of Special Medicine Daping HospitalArmy Medical UniversityChongqing 400042China

Intermittent theta burst stimulation(iTBS),a time-saving and cost-effective repetitive transcranial magnetic stimulation regime,has been shown to improve cognition in patients with Alzheimer’s disease(AD).However,the specific mechanism underlying iTBS-induced cognitive enhancement remains unknown.Previous studies suggested that mitochondrial functions are modulated by magnetic stimulation.Here,we showed that iTBS upregulates the expression of iron-sulfur cluster assembly 1(ISCA1,an essential regulatory factor for mitochondrial respiration)in the brain of APP/PS1 mice.In vivo and in vitro studies revealed that iTBS modulates mitochondrial iron-sulfur cluster assembly to facilitate mitochondrial respiration and function,which is required for ISCA1.Moreover,iTBS rescues cognitive decline and attenuates AD-type pathologies in APP/PS1 mice.The present study uncovers a novel mechanism by which iTBS modulates mitochondrial respiration and function via ISCA1-mediated iron-sulfur cluster assembly to alleviate cognitive impairments and pathologies in AD.We provide the mechanistic target of iTBS that warrants its therapeutic potential for AD patients.

关键词： Intermittent theta burst stimulation Alzheimer’s disease Iron-sulfur cluster assembly 1 Mitochondrial dysfunction Neurodegeneration

Learnware:small models do big

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Science China(Information Sciences) 2024年第1期67卷 39-50页

作者： zhi-Hua ZHOU zhi-hao TAN National Key Laboratory for Novel Software Technology Nanjing University

There are complaints about current machine learning techniques such as the requirement of a huge amount of training data and proficient training skills,the difficulty of continual learning,the risk of catastrophic forgetting,and the leaking of data privacy/proprietary.Most research efforts have been focusing on one of those concerned issues separately,paying less attention to the fact that most issues are entangled in practice.The prevailing big model paradigm,which has achieved impressive results in natural language processing and computer vision applications,has not yet addressed those issues,whereas becoming a serious source of carbon emissions.This article offers an overview of the learnware paradigm,which attempts to enable users not to need to build machine learning models from scratch,with the hope of reusing small models to do things even beyond their original purposes,where the key ingredient is the specification which enables a trained model to be adequately identified to reuse according to the requirement of future users who know nothing about the model in advance.

关键词： artificial intelligence machine learning learnware

P-symmetric Subharmonic Solutions for Nonlinear Hamiltonian Systems

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Acta Mathematica Sinica,English Series 2024年第6期40卷 1388-1408页

作者： Duan zhi ZHANG zhi hao Zhao School of Mathematical Sciences Nankai UniversityTianjin 300071P.R.China

In this paper,we prove that for each positive k≡1 mod m there exists a P-symmetric kmτ-periodic solution xk for asymptotically linear mτ-periodic Hamiltonian systems,which are nonautonomous and endowed with a P-symmetry.If the P-symmetric Hamiltonian function is semi-positive,one can prove,under a new iteration inequality of the Maslov-type P-index,that xk_(1) and xk_(2) are geometrically distinct for k_(1)/k_(2)≥(2n+1)m+1;and xk_(1),xk_(2) are geometrically distinct for k_(1)/k_(2)≥m+1 provided xk_(1) is non-degenerate.

关键词： P-symmetric subharmonic Hamiltonian systems Maslov-type index theory iteration inequality asymptotically linear