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Delayed plasticity during spherical nanoindentation of an iron-chromium-aluminum alloy:Effect of ferric ion irradiation

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Journal of Materials Science & Technology 2023年第36期167卷 228-236页

作者： Y.Zhang C.W.Li J.L.Jiang J.F.gu H.wang Y.D.Jia g.wang X.g.An Q.wang J.Lu Institute of Materials Shanghai UniversityShanghai 200072China School of Materials Science and Engineering Shanghai Jiao Tong UniversityShanghai 200240China Department of Mechanical Engineering City University of Hong KongKowloonSARChina Science and Technology on Reactor Fuel and Materials Laboratory Nuclear Power Institute of ChinaChengdu 610041China Interdisciplinary Materials Research Center Institute for Advanced StudyChengdu UniversityChengdu610106China

Spherical nanoindentation of an iron-chromium-aluminum alloy was conducted to study the effect of ferric-ion(Fe 3+)irradiation on the time-dependent plasticity behavior in the surface layers of this alloy.It was observed that the initiation of plasticity by the appearance of displacement burst or“pop-in”event occurred after a period of waiting time in the apparent elastic regime and that Fe^(3+)irradiation at 360°C and up to∼0.5 displacements per atom could make it happen under the lower applied loads but with a reduced magnitude.Through the experimental data,an activation volume and activation energy were extracted for the delayed plasticity.The results show that Fe^(3+)-irradiation significantly reduced its acti-vation volume from∼3.05 b 3 to∼1.75 b 3(where b=Burgers vector),but slightly increased its activation energy from∼0.65 to∼0.71 eV.On the other hand,high-resolution scanning transmission electron mi-croscopy observations reveal that the irradiation at the elevated temperature created interstitial atom pair onto the(100)habit plane that can serve as the nucleation site of a100dislocation loop while elim-inating the pre-existing dislocations.Consequently,it is indicated that heterogeneous nucleation of the dislocation loop was predominant in the delayed plasticity initiation of this alloy and that the nucleation of the interstitial-type dislocation loop was involved due to Fe^(3+)-irradiation.

关键词： Spherical nanoindentation Delayed plasticity FeCrAl alloy Fe^(3+)-irradiation

Osteogenesis and angiogenesis of a bulk metallic glass for biomedical implants

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Bioactive Materials 2022年第2期7卷 253-266页

作者： K.Sun R.Fu X.W.Liu L.M.Xu g.wang S.Y.Chen Q.J.Zhai S.Pauly Institute of Materials Shanghai UniversityShanghai200444China Department of Neurology Tongren HospitalSchool of MedicineShanghai Jiao Tong UniversityShanghai200336China Sports Medicine Department of Huashan Hospital Fudan UniversityShanghai200040China University of Applied Sciences Aschaffenburg Würzburger Straße 45D-63743AschaffenburgGermany

Implantation is an essential issue in orthopedic surgery.Bulk metallic glasses(BMgs),as a kind of novel materials,attract lots of attentions in biological field owing to their comprehensive excellent properties.Here,we show that a Zr_(61)Ti_(2)Cu_(25)Al_(12)(at.%)BMg(Zr-based BMg)displays the best cytocompatibility,pronounced positive effects on cellular migration,and tube formation from in-vitro tests as compared to those of commercial-pure titanium and poly-ether-ether-ketone.The in-vivo micro-CT and histological evaluation demonstrate the Zr-based BMg can significantly promote a bone formation.Immunofluorescence tests and digital reconstructed radiographs manifest a stimulated effect on early blood vessel formation from the Zr-based BMg.Accordingly,the intimate connection and coupling effect between angiogenesis and osteogenesis must be effective during bone regeneration after implanting Zr-based BMg.Dynamic gait analysis in rats after implanting Zr-based BMg demonstrates a tendency to decrease the pain level during recovery,simultaneously,without abnormal ionic accumulation and inflammatory reactions.Considering suitable mechanical properties,we provide a realistic candidate of the Zr61Ti2Cu25Al12 BMg for biomedical applications.

关键词： Metallic glasses Bio-corrosion Biocompatibility Osteogenesis Angiogenesis

Strengthening and deformation mechanism of high-strength CrMnFeCoNi high entropy alloy prepared by powder metallurgy

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Journal of Materials Science & Technology 2023年第1期132卷 119-131页

作者： Y.Xing C.J.Li Y.K.Mu Y.D.Jia K.K.Song J.Tan g.wang Z.Q.Zhang J.H.Yi J.Eckert Faculty of Materials Science and Engineering Kunming University of Science and TechnologyKunming 650093China Laboratory for Microstructures Institute of MaterialsShanghai UniversityShanghai 200444China School of Mechanical Electrical&Information EngineeringShandong UniversityWeihai 264209China College of Materials Science and Engineering Chongqing UniversityChongqing 400044China Erich Schmid Institute of Materials Science Austrian Academy of SciencesJahnstraße 12Leoben A-8700Austria Department of Materials Science Chair of Materials PhysicsMontanuniversität LeobenJahnstraße 12Leoben A-8700Austria Adjunct with National University of Science and Technology«MISiS» Leninsky Prosp.4Moscow 119049Russia

Multiphase CrMnFeCoNi high-entropy alloys(HEAs)were prepared by a powder metallurgy process com-bining mechanical alloying(MA)and vacuum hot-pressing sintering(HPS).The single-phase face-centered cubic(FCC)HEA powder prepared by MA was sintered into a bulk HEA specimen containing FCC phase matrix along with precipitated M 23 C 6 phase and nanoscaleσphase particles.When the sintering temper-ature was 1223 K,the ultimate strength reaches 1300±11.6 MPa,and the elongation exceeds 4%±0.6%.Microstructural characterization reveals that the formation of nanoscale particles and deformation twins play critical roles in improving the strain hardening(SH)ability.Prolonging the MA time promoted the formation of the precipitated phase and enhanced the SH ability by increasing the number of precip-itated particles.The SH capacity increases significantly with increasing sintering temperature,which is attributed to a significant enhancement in the twinning capacity due to grain growth and the reduced number ofσphase particles.Through systematic studies,the planar glide of dislocations was found to be the main mode of deformation,while deformation twinning appeared as an auxiliary deformation mode when the twinning stress was reached.Although the formation of precipitates leads to grain bound-ary and precipitation strengthening effects,crack initiation is more prominent owing to increased grain boundary brittleness around the precipitated M 23 C 6 phase.The prominence of crack initiation is a contra-diction that must be reconciled with regard to precipitation strengthening.This work serves as a useful reference for the preparation of high-strength HEA parts by powder metallurgy.

关键词： High entropy alloy Powder processing grain reﬁnement Precipitation strengthening Deformation twinning

Effect of Heat Treatment Time on Dy–Cu Alloy Diffusion Process in Dy-Containing Commercial Nd–Fe–B Sintered Magnets

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Acta Metallurgica Sinica(English Letters) 2018年第5期31卷 496-502页

作者： H.Y.Liu g.wang Y.Hong D.C.Zeng School of Materials Science and Engineering South China University of Technology

In this paper, the grain boundary diffusion process（gBDP） using a Dy70Cu30（at.%） alloy as the diffusion source was performed in a commercial sintered Nd–Fe–B magnet, and the effect of heat treatment time on the microstructure and magnetic properties of the magnet was investigated in detail. For the processed magnets heat-treated at 860℃, as heat treatment time increased, the coercivity and the depth of（Nd,Dy）2Fe14B core–shell structure increased first and then decreased. However, when the heat treatment time was more than 2 h, the diffusion path of Dy from the Dy-rich shell phase into the Nd2Fe14B grains was revealed, and a nearly homogeneous（Nd,Dy）2Fe14B phase was formed, which brought on the decrease in both the depth of visible core–shell structure and the coercivity of Nd–Fe–B magnet.

关键词： Sintered Nd-Fe-B magnets grain boundary diffusion Heat treatment time Coercivity Micromagnetic simulation

He-enhanced heterogeneity of radiation-induced segregation in FeNiCoCr high-entropy alloy

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Journal of Materials Science & Technology 2022年第6期101卷 226-233页

作者： W.T.Lin g.M.Yeli g.wang J.H.Lin S.J.Zhao D.Chen S.F.Liu F.L.Meng Y.R.Li F.He Y.Lu J.J.Kai Department of Mechanical Engineering City University of Hong KongHong KongChina Institute of Nuclear&New Energy Technology Tsinghua UniversityBeijingChina Department of Physics Southern University of Science and TechnologyShenzhenChina Centre for Advanced Nuclear Safety and Sustainable Development City University of Hong KongHong KongChina School of Environmental Science and Engineering Southern University of Science and TechnologyShenzhenChina School of Materials Science and Engineering Shanghai UniversityShanghaiChina Nano-Manufacturing Laboratory(NML) City University of Hong Kong Shenzhen Research InstituteShenzhenChina

Radiation-induced segregation(RIS) is a typical non-equilibrium process that can dramatically alter the behavior of defect sinks and material properties under irradiation. However, RIS mechanisms have been rarely studied around small He bubbles owing to the technical challenges involved in direct measurements of local chemistry. Here, using state-of-the-art atom probe tomography, we report the RIS behavior near He bubbles in the Fe Ni Co Cr high-entropy alloy that indicates Co segregates most strongly, followed by weaker Ni segregation, whereas Fe and Cr are depleted almost to the same degree. Exceptionally, the magnitude of Co segregation around He bubbles is higher than previously measured values at voids and dislocation loops. Electron energy-loss spectroscopy was used to measure the He density and pressure inside individual bubbles. We demonstrate that He bubbles are over-pressurized at the irradiation temperature that could result in the vacancy bias and the subsequent vacancy-dominated RIS mechanism.First-principles calculations further reveal that there are repulsive interactions between He and Co atoms that may reduce the frequency of Co-vacancy exchange. As a result, He atoms likely retard Co diffusion via the vacancy mechanism and enhance the heterogeneity of RIS in Co-containing multicomponent alloys. These insights could provide the basis for understanding He effects in nuclear materials and open an avenue for tailoring the local chemical order of medium-and high-entropy alloys.

关键词： High-entropy alloy Radiation-induced segregation He bubbles Atom probe tomography Electron energy-loss spectroscopy

Plastic Flow of a Cu_(50)Zr_(45)Ti_5 Bulk Metallic glass Composite

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Journal of Materials Science & Technology 2014年第6期30卷 609-615页

作者： g.wang S.Pauly S.gorantla N.Mattern J.Eckert Laboratory for Microstructures Shanghai University IFW-Dresden Institute for Complex Materials Helmholtzstr. 20D-01069 Dresden Germany TU Dresden Institute of Materials ScienceD-01062 Dresden Germany

By modifying the cooling rate, a Cu50Zr45Ti5 alloy with various structures was developed. A fully glassy rod and specimens with different sizes and volume fractions ofnanocrystals were produced. The relationship between the structure and mechanical properties of the Cu50Zr45Ti5 alloy was investigated. The different structures result in a transition of the deformation mechanism from being dominated by shear banding to being governed by dislocation action accompanied by shear band formation. These different plastic deformation mechanisms were discussed in the framework of self-organized critical behavior.

关键词： Bulk metallic glass Plasticity Self-organized critical behavior Bulk metallic glass composite

Critical transitions in the shape morphing of kirigami metallic glass

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Journal of Materials Science & Technology 2021年第2期61卷 204-212页

作者： D.X.Han L.Zhao S.H.Chen g.wang K.C.Chan Advanced Manufacturing Technology Research Center Department of Industrial and Systems EngineeringThe Hong Kong Polytechnic UniversityHung HornKowloonHong KongChina School of Mechanical Engineering Hefei University of TechnologyHefei230009China Laboratory for Microstructures Institute of MaterialsShanghai UniversityShanghai200444China

Kirigami, the ancient Japanese paper cutting technique, has been applied to achieve high stretchability and low energy loss of designed metallic glass. Despite the exploration of the underlying deformation mechanism of kirigami-inspired structures from the energy point of view, the morphable responses of the kirigami patterns and the origin of the kirigami response are yet to be fully understood. This study reveals the mechanical driven-forms of the kirigami structure with the corresponding deformation stages. Based on the beam deflection theory, the elastic buckling behavior of kirigami metallic glass is manifested and a critical force prediction model is developed. Moreover, a force concentration parameter is introduced in the rigid-plastic deformation stage, predicting the nominal ultimate force. The kirigami-inspired facture force is firstly proposed. The findings of these models are in good agreement with the experimental sizedependent kirigami responses, and expected to provide significant insights into the understanding of the deformation behavior and the design of kirigami metallic glasses.

关键词： Metamaterial Kirigami metallic glass Critical load Size effect Beam deflection

Haplotype-based phylogenetic analysis and population genomics uncover the origin and domestication of sweetpotato

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Molecular Plant 2024年第2期17卷 277-296页

作者： Mengxiao Yan Ming Li Yunze wang Xinyi wang M-Hossein Moeinzadeh Dora g.Quispe-Huamanquispe Weijuan Fan Yijie Fang Yuqin wang Haozhen Nie Zhangying.wang Aiko Tanaka Bettina Heider Jan F.Kreuze godelieve gheysen Hongxia wang Martin Vingron Ralph Bock Jun Yang Shanghai Key Laboratory of Plant Functional genomics and Resources Shanghai Chenshan Botanical GardenShanghai 201602China College of Life Sciences Chongqing Normal UniversityChongqing 401331China Biotechnology and Nuclear Technology Research Institute Sichuan Academy of Agricultural SciencesChengdu 610061China College of Life Sciences Shanghai Normal UniversityShanghai 200234China Department of Computational Molecular Biology Max Planck Institute for Molecular GeneticsIhnestraBe 63-7314195 BerlinGermany Department of Biotechnology Ghent University9000 GhentBelgium guangdong Provincial Key Laboratory of Crops genetics and Improvement Crop Research InstituteGuangdong Academy of Agricultural SciencesGuangzhou 510640China graduate School of Bioagricultural Sciences Nagoya UniversityChikusaNagoya 464-8601Japan international Potato Center(CIP) LimaPeru CAS Center for Excellence of Molecular Plant Sciences Institute of Plant Physiology and EcologyChinese Academy of SciencesShanghai 200233China Max-Planck-Institut fur Molekulare Pflanzenphysiologie Am Muhlenberg 114476 Potsdam-GolmGermany

The hexaploid sweetpotato(lpomoea batatas)is one of the most important root crops worldwide.However,its genetic origin remains controversial,and its domestication history remains unknown.In this study,we used a range of genetic evidence and a newly developed haplotype-based phylogenetic analysis to identify two probable progenitors of sweetpotato.The diploid progenitor was likely closely related to lpomoea ae-quatoriensis and contributed the B,subgenome,IbT-DNA2,and the lineage 1 type of chloroplast genome to sweetpotato.The tetraploid progenitor of sweetpotato was most likely l.batatas 4x,which donated the B2 subgenome,IbT-DNA1,and the lineage 2 type of chloroplast genome.Sweetpotato most likely originated from reciprocal crosses between the diploid and tetraploid progenitors,followed by a subsequent whole-genome duplication.In addition,we detected biased gene exchanges between the subgenomes;the rate of B,to B2 subgenome conversions was nearly three times higher than that of B2 to B subgenome conver-sions.Our analyses revealed that genes involved in storage root formation,maintenance of genome stabil-ity,biotic resistance,sugar transport,and potassium uptake were selected during the speciation and domestication of sweetpotato.This study sheds light on the evolution of sweetpotato and paves the way forimprovementofthiscrop.

关键词： sweetpotato origin gene conversion domestication IbT-DNA HPA

Assessment of tree-ring mercury radial translocation and age effect in Masson pine:Implications for historical atmospheric mercury reconstruction

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Journal of Environmental Sciences 2024年第4期138卷 266-276页

作者： Xu Liu Xun wang Dingyong.wang College of Resources and Environment Southwest UniversityChongqing 400715China State Key Laboratory of Environmental geochemistry Institute of GeochemistryChinese Academy of SciencesGuiyang 550081China

The tree ring has been regarded as an emerging archive to reconstruct historical atmospheric mercury(Hg)trends,but with the large knowledge gaps in the reliability.In this study,we comprehensively evaluated the Hg source,radial translocation and age effect of Masson pine(Pinus massoniana)tree ring at Mt.Jinyun in Chongqing,to assess the suitability of such tree ring as the archive of atmospheric Hg.Results showed that distinct variabilities among Masson pine tree-ring Hg concentration profiles.The Hg concentration significantly increased along with stem height(Pg the Hg in tree rings mainly derived from foliage uptake atmospheric Hg.We found a distinct age effect that the tree ring of young trees had the higher Hg concentration.Besides,we used the advection-diffusion model to demonstrate how Hg concentration shifted by the advection or/and diffusion in tree rings.The modeling results showed that the advection induced radial translocation during the young growth period of tree was a plausible mechanism to result in the tree-ring Hg record largely different from the trend of anthropogenic Hg emissions in Chongqing.We finally suggest that in further Hg dendrochemistry,better discarding the tree-ring Hg profile of the young growth period to reduce impacts of the radial translocation and age effect.

关键词： Masson pine Tree-ring mercury Radial translocation Tree age effect