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Microstructural evolution and mechanism of grain growth in magnesia ceramics prepared by high pressure and temperature with ultra-high heating rate

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Science China(Technological Sciences) 2014年第6期57卷 1085-1092页

作者： LIU JiangHao FU ZhengYi WANG WeiMin ZHANG JinYong WANG Hao WANG YuCheng LEE SooWohn NIIHARA Koichi State Key Laboratory of Advanced Technology for materials Synthesis and Processing Wuhan University of Technology Department of Environmental Engineering Sun Moon University extreme Energy-Density Research institute Nagaoka University of Technology1603-1 KamitomiokaNagaokaNiigata 940-2188Japan

The fast densification method of combustion reaction plus quick pressing was adopted to prepare nanocrystalline *** densification process of magnesia compact with a particle size of 100 nm was investigated,under the applied pressure of up to 170 MPa,and the temperature range of 1740–2080 K with ultra-high heating rate(above 1700 K/min).High-purity magnesia ceramics with a relative density of 98.8%and an average grain size of 120 nm was obtained at 1740 K,and the grain growth during the densification process was effectively *** characteristic morphology of evaporation-condensation was observed in the compact prepared at 2080 K,which revealed the actual process of mass transfer by gas ***,the investigation on the microstructure evolution and mechanism of grain growth was carried out,on the basis of as-preserved nanocrystalline *** result indicated that the grain growth of the nanocrystalline MgO was controlled by the mechanism of evaporation-condensation rather than surface ***,the pressure had an influence of restraining the grain growth based on solid diffusion and strengthening the effect of gas diffusion with the increasing *** the particular conditions,there existed an appropriate temperature for the densification of nanocrystalline magnesia,while the excessive temperature would exaggerate grain growth and impede densification.

关键词： grain growth densification heating rate evaporation-condensation surface diffusion nanocrystalline ceramics

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Predicting the propensity for thermally activated β events in metallic glasses via interpretable machine learning

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npj Computational materials 2020年第1期6卷 46-57页

作者： Qi Wang Jun Ding Longfei Zhang Evgeny Podryabinkin Alexander Shapeev Evan Ma Department of materials Science and Engineering Johns Hopkins UniversityBaltimoreMD 21218USA Center for Advancing materials Performance from the Nanoscale(CAMP-Nano) State Key Laboratory for Mechanical Behavior of MaterialsXi’an Jiaotong UniversityXi’an 710049China Department of Computer Science Johns Hopkins UniversityBaltimoreMD 21218USA Center for Energy Science and Technology Skolkovo Institute of Science and Technology3 Nobel StreetMoscow 143026Russia

The elementary excitations in metallic glasses(MGs),i.e.,β processes that involve hopping between nearby sub-basins,underlie many unusual properties of the amorphous alloys.A high-efficacy prediction of the propensity for those activated processes from solely the atomic positions,however,has remained a daunting ***,employing well-designed site environment descriptors and machine learning(ML),notable progress has been made in predicting the propensity for stress-activated β processes(i.e.,shear transformations)from the static structure.

关键词： structure glasses metallic

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Tailoring electronic properties of two-dimensional antimonene with isoelectronic counterparts

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Chinese Physics B 2020年第3期29卷 41-49页

作者： Ye Zhang Huai-Hong Guo Bao-Juan Dong Zhen Zhu Teng Yang Ji-Zhang Wang Zhi-Dong Zhang College of Sciences Liaoning Shihua UniversityFushun 113001China Shenyang National Laboratory for materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China materials Department University of CaliforniaSanta BarbaraCA 93106USA State Key Laboratory of Quantum Optics and Quantum Optics Devices Institute of Opto-ElectronicsShanxi UniversityTaiyuan 030006China Collaborative Innovation Center of extreme Optics Shanxi UniversityTaiyuan 030006China

Using ab initio density functional theory calculations, we explore the three most stable structural phases, namely, α,β, and cubic(c) phases, of two-dimensional(2D) antimonene, as well as its isoelectronic counterparts SnTe and InI. We find that the band gap increases monotonically from Sb to SnTe to InI along with an increase in ionicity, independent of the structural phases. The band gaps of this material family cover the entire visible-light energy spectrum, ranging from 0.26 eV to 3.37 eV, rendering them promising candidates for optoelectronic applications. Meanwhile, band-edge positions of these materials are explored and all three types of band alignments can be achieved through properly combining antimonene with its isoelectronic counterparts to form heterostructures. The richness in electronic properties for this isoelectronic material family sheds light on possibilities to tailor the fundamental band gap of antimonene via lateral alloying or forming vertical heterostructures.

关键词： tailoring electronic properties two-dimensional antimonene isoelectronic counterparts

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Fundamental band gap and alignment of two-dimensional semiconductors explored by machine learning

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Chinese Physics B 2020年第4期29卷 327-335页

作者： Zhen Zhu Baojuan Dong Huaihong Guo Teng Yang Zhidong Zhang materials Department University of CaliforniaSanta BarbaraCA 93106USA Shenyang National Laboratory for materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China College of Sciences Liaoning Shihua UniversityFushun 113001China State Key Laboratory of Quantum Optics and Quantum Optics Devices Institute of Opto-ElectronicsShanxi UniversityTaiyuan 030006China Collaborative Innovation Center of extreme Optics Shanxi UniversityTaiyuan 030006China

Two-dimensional(2D)semiconductors isoelectronic to phosphorene have been drawing much attention recently due to their promising applications for next-generation(opt)*** family of 2D materials contains more than 400members,including(a)elemental group-V materials,(b)binary III–VII and IV–VI compounds,(c)ternary III–VI–VII and IV–V–VII compounds,making materials design with targeted functionality unprecedentedly rich and extremely *** shed light on rational functionality design with this family of materials,we systemically explore their fundamental band gaps and alignments using hybrid density functional theory(DFT)in combination with machine ***,calculations are performed using both the Perdew–Burke–Ernzerhof exchange–correlation functional within the generalgradient-density approximation(GGA-PBE)and Heyd–Scuseria–Ernzerhof hybrid functional(HSE)as a *** find this family of materials share similar crystalline structures,but possess largely distributed band-gap values ranging approximately from 0 eV to 8 ***,we apply machine learning methods,including linear regression(LR),random forest regression(RFR),and support vector machine regression(SVR),to build models for the prediction of electronic *** these models,SVR is found to have the best performance,yielding the root mean square error(RMSE)less than 0.15 eV for the predicted band gaps,valence-band maximums(VBMs),and conduction-band minimums(CBMs)when both PBE results and elemental information are used as ***,we demonstrate that the machine learning models are universally suitable for screening 2D isoelectronic systems with targeted functionality,and especially valuable for the design of alloys and heterogeneous systems.

关键词： two-dimensional semiconductors machine learning

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Competitive oxidation behavior of Ni-based superalloy GH4738 at extreme temperature

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International Journal of Minerals,Metallurgy and materials 2024年第1期31卷 138-145页

作者： Hui Xu Shufeng Yang Enhui Wang Yunsong Liu Chunyu Guo Xinmei Hou Yanling Zhang State Key Laboratory of Advanced Metallurgy University of Science and Technology BeijingBeijing 100083China institute for carbon neutrality University of Science and Technology BeijingBeijing 100083China

A high thrust-to-weight ratio poses challenges to the high-temperature performance of Ni-based superalloys. The oxidation behavior of GH4738 at extreme temperatures has been investigated by isothermal and non-isothermal experiments. As a result of the competitive diffusion of alloying elements, the oxide scale included an outermost porous oxide layer (OOL), an inner relatively dense oxide layer (IOL), and an internal oxide zone (IOZ), depending on the temperature and time. A high temperature led to the formation of large voids at the IOL/IOZ interface. At 1200℃, the continuity of the Cr-rich oxide layer in the IOL was destroyed, and thus, spallation occurred. Extension of oxidation time contributed to the size of Al-rich oxide particles with the increase in the IOZ. Based on this finding,the oxidation kinetics of GH4738 was discussed, and the corresponding oxidation behavior at 900-1100℃ was predicted.

关键词： Ni-based superalloy GH4738 extreme temperature competitive oxidation oxidation mechanism oxidation kinetics

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Closed-loop superconducting materials discovery

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npj Computational materials 2023年第1期9卷 471-478页

作者： Elizabeth A.Pogue Alexander New Kyle McElroy Nam Q.Le Michael J.Pekala Ian McCue Eddie Gienger Janna Domenico Elizabeth Hedrick Tyrel M.McQueen Brandon Wilfong Christine D.Piatko Christopher R.Ratto Andrew Lennon Christine Chung Timothy Montalbano Gregory Bassen Christopher D.Stiles Research and Exploratory Development Department Johns Hopkins University Applied Physics Laboratory11100 Johns Hopkins RoadLaurel 20723 MDUSA Department of materials Science and Engineering Northwestern University2220 Campus DriveEvanston 60208 ILUSA Department of materials Science and Engineering Johns Hopkins University3400 N.Charles StreetBaltimore 21218 MDUSA Department of Chemistry Johns Hopkins University3400 N.Charles StreetBaltimore 21218 MDUSA institute for Quantum Matter William H.Miller III Department of Physics and AstronomyJohns Hopkins University3400 N.Charles StreetBaltimore 21218 MDUSA

Discovery of novel materials is slow but necessary for societal ***,we demonstrate a closed-loop machine learning(ML)approach to rapidly explore a large materials search space,accelerating the intentional discovery of superconducting *** experimentally validating the results of the ML-generated superconductivity predictions and feeding those data back into the ML model to refine,we demonstrate that success rates for superconductor discovery can be more than *** four closed-loop cycles,we report discovery of a superconductor in the Zr-In-Ni system,re-discovery of five superconductors unknown in the training datasets,and identification of two additional phase diagrams of interest for new superconducting *** work demonstrates the critical role experimental feedback provides in ML-driven discovery,and provides a blueprint for how to accelerate materials progress.

关键词： discovery materials loop

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Measurement of metal vapor cooling speed during nanoparticle formation by pulsed wire discharge

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中国有色金属学会会刊：英文版 2009年第B09期19卷 183-188页

作者： Yuu SHIKODA Yoshinori TOKOI Koji SUWA Satoru ISHIHARA Tsuneo SUZUKI Tadachika NAKAYAMA Hisayuki SUEMATSU Koichi NIIHARA extreme Energy-Density Research institute Nagaoka University of Technology Department of Electrical and Electronic Engineering Niigata University Inovertion Satellite Niigata Japan Science and Technology Agency

Pulsed wire discharge(PWD) is one of nano-sized powder production methods. The object of this work is to study influence of the plasma/vapor/particle density using computer simulation and to establish temperature measurement method using a high-speed infrared thermometer in the PWD process. The temperature correction coefficient was obtained from geometric computer simulation results. Obtained correction coefficient was applied to the temperature measuring results. It was found from this result that obtained correction coefficient was appropriate. A temperature measurement method was established by using the high-speed infrared thermometer in PWD.

关键词：测量方法金属蒸气形成速度放电脉冲纳米导线红外线温度计计算机模拟冷却

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Unveiling anneal hardening in dilute Al-doped Al_(x)CoCrFeMnNi(x = 0,0.1) high-entropy alloys

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Journal of materials Science & Technology 2021年第32期91卷 270-277页

作者： Q.Cheng X.D.Xu P.Xie L.L.Han J.Y.He X.Q.Li J.Zhang Z.T.Li Y.P.Li B.Liu T.G.Nieh M.W.Chen J.H.Chen Centre for High Resolution Electron Microscopy College of Materials Science and EngineeringHunan UniversityChangsha 410082China State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China Applied materials Physics Department of Materials Science and EngineeringKTH-Royal Institute of TechnologyStockholm SE10044Sweden Department of materials Science and Engineering University of TennesseeKnoxvilleTN37996United States Department of materials Science and Engineering Johns Hopkins UniversityBaltimoreMD 21214USA

Anneal hardening has been one of the approaches to improve mechanical properties of solid solution alloys with the face-centered cubic(FCC) structure,whereby a considerable strengthening can be attained by annealing of cold-worked alloys below the recrystallization temperature(T_(rx)).Microscopically,this hardening effect has been ascribed to several mechanisms,*** segregation to defects(dislocation and stacking fault) and short-range chemical ordering,***,none of these mechanisms can well explain the anneal hardening recently observed in phase-pure and coarse-grained FCC-structured high-entropy alloys(HEAs).Here we report the observations,using high-resolution electron channeling contrast imaging and transmission electron microscopy,of profuse and stable dislocation substructures in a cold-rolled CoCrFeMnNi HEA subject to an annealing below T_(rx).The dislocation substructures are observed to be thermally stable up to T_(rx),which could arise from the chemical complexity of the high-entropy system where certain elemental diffusion retardation *** microstructure feature is markedly different from that of conventional dilute solid solution alloys,in which dislocation substructures gradually vanish by recovery during annealing,leading to a strength ***,dilute addition of 2 at.% Al leads to a reduction in both microhardness and yield strength of the cold-rolled and subsequently annealed(≤500℃) *** Al induced softening effect,could be associated with the anisotropic formation of dislocation substructure,resulting from enhanced dislocation planar slip due to glide plane softening *** findings suggest that the strength of HEAs can be tailored through the anneal hardening effect from dislocation substructure strengthening.

关键词： Annealing hardening Dislocation substructure strengthening High-entropy alloy Solid solution structure

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Translational bioengineering strategies for peripheral nerve regeneration:opportunities,challenges,and novel concepts

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Neural Regeneration Research 2023年第6期18卷 1229-1234页

作者： Karim A.Sarhane Chenhu Qiu Thomas G.W.Harris Philip J.Hanwright Hai-Quan Mao Sami H.Tuffaha Department of Plastic and Reconstructive Surgery Peripheral Nerve Research LaboratoryJohns Hopkins University School of MedicineBaltimoreMDUSA Department of materials Science and Engineering Johns Hopkins University Whiting School of EngineeringBaltimoreMDUSA institute for NanoBioTechnology Johns Hopkins UniversityBaltimoreMDUSA Translational Tissue Engineering Center Johns Hopkins University School of MedicineBaltimoreMDUSA Department of Biomedical Engineering Johns Hopkins University School of MedicineBaltimoreMDUSA

Peripheral nerve injuries remain a challenging problem in need of better treatment *** best efforts at surgical reconstruction and postoperative rehabilitation,patients are often left with persistent,debilitating motor and sensory *** are currently no therapeutic strategies proven to enhance the regenerative process in humans.A clinical need exists for the development of technologies to promote nerve regeneration and improve functional *** advances in the fields of tissue engineering and nanotechnology have enabled biomaterial scaffolds to modulate the host response to tissue repair through tailored mechanical,chemical,and conductive *** bioengineered approaches have enabled targeted,sustained delivery of protein therapeutics with the capacity to unlock the clinical potential of a myriad of neurotrophic growth factors that have demonstrated promise in enhancing regenerative *** such,further exploration of combinatory strategies leveraging these technological advances may offer a pathway towards clinically translatable solutions to advance the care of patients with peripheral nerve *** review first presents the various emerging bioengineering strategies that can be applied for the management of nerve gap *** cover the rationale and limitations for their use as an alternative to autografts,focusing on the approaches to increase the number of regenerating axons crossing the repair site,and facilitating their growth towards the distal *** also discuss the emerging growth factor-based therapeutic strategies designed to improve functional outcomes in a multimodal fashion,by accelerating axonal growth,improving the distal regenerative environment,and preventing end-organs atrophy.

关键词： bioengineering biomaterials growth hormone insulin-like growth factor 1 nanotechnology neurobiology peripheral nerve regeneration Schwann cells translational research

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Regulating off-centering distortion maximizes photoluminescence in halide perovskites

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National Science Review 2021年第9期8卷 60-67页

作者： Xujie Lu Constantinos Stoumpos Qingyang Hu Xuedan Ma Dongzhou Zhang Songhao Guo Justin Hoffman Kejun Bu Xiaofeng Guo Yingqi Wang Cheng Ji Haijie Chen Hongwu Xu Quanxi Jia Wenge Yang Mercouri G.Kanatzidis Ho-Kwang Mao Center for High Pressure Science and Technology Advanced Research Department of Chemistry Northwestern University Department of materials Science and Technology Voutes Campus University of Crete Center for Nanoscale materials Argonne National Laboratory Partnership for extreme Crystallography University of Hawaii at Manoa Department of Chemistry and Alexandra Navrotsky institute for Experimental Thermodynamics Washington State University Earth and Environmental Sciences Division Los Alamos National LaboratoryLos Alamos Department of materials Design and Innovation University at Buffalo The State University of New York

Metal halide perovskites possess unique atomic and electronic configurations that endow them with high defect tolerance and enable high-performance photovoltaics and optoelectronics. Perovskite light-emitting diodes have achieved an external quantum efficiency of over 20%. Despite tremendous progress,fundamental questions remain, such as how structural distortion affects the optical properties. Addressing their relationships is considerably challenging due to the scarcity of effective diagnostic tools during structural and property tuning as well as the limited tunability achievable by conventional methods. Here,using pressure and chemical methods to regulate the metal off-centering distortion, we demonstrate the giant tunability of photoluminescence (PL) in both the intensity (>20 times) and wavelength(>180 nm/GPa) in the highly distorted halide perovskites [CH3NH3GeI3, HC(NH2)2GeI3, and Cs Ge I3].Using advanced in situ high-pressure probes and first-principles calculations, we quantitatively reveal a universal relationship whereby regulating the level of off-centering distortion towards 0.2 leads to the best PL performance in the halide perovskites. By applying this principle, intense PL can still be induced by substituting CH3NH~3+with Cs~+to control the distortion in (CH3NH3)1-xCsxGeI3, where the chemical substitution plays a similar role as external pressure. The compression of a fully substituted sample of CsGe I3further tunes the distortion to the optimal value at 0.7 GPa, which maximizes the emission with a10-fold enhancement. This work not only demonstrates a quantitative relationship between structural distortion and PL property of the halide perovskites but also illustrates the use of knowledge gained from high-pressure research to achieve the desired properties by ambient methods.

关键词： halide perovskites high pressure off-centering distortion optical properties lone-pair electrons quantitative relationship

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