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Acta Mechanica Solida Sinica 1996年第3期9卷 189-200页

作者： Pan, WK Zhang, YW Wang, TC UNIV SCI & TECHNOL CHINA HEFEI 230026PEOPLES R CHINA CHINESE ACAD SCI INST MECHBEIJING 100080PEOPLES R CHINA

By combining Grain boundary (GB) and its influence zone, a micromechanic model for polycrystal is established for considering the influence of GB. By using the crystal plasticity theory and the finite element method for finite deformation, numerical simulation is carried out by the model. Calculated results display the microscopic characteristic of deformation fields of grains and are in qualitative agreement with experimental results.

关键词： Grain boundary slip slid crystal plasticity finite deformation

Enhanced nanocrystalline stability of BCC iron via copper segregation

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Progress in Natural Science:Materials International 2023年第2期33卷 185-192页

作者： Feiyang Wang Linshuo Dong Hong-Hui Wu Penghui Bai Shuize Wang Guilin Wu Junheng Gao Jiaming Zhu Xiaoye Zhou Xinping Mao Beijing Advanced Innovation Center for Materials Genome Engineering Institute for Carbon Neutrality University of Science and Technology Beijing Institute of Materials Intelligent Technology Liaoning Academy of Materials 3. Institute of Steel Sustainable Technology Liaoning Academy of Materials School of Civil Engineering Shandong University Department of Materials Science and Engineering Shenzhen MSU-BIT University

Nanocrystalline alloys are known for their high density of grain boundaries(GBs), which results in low thermal stability and a tendency for coarsening. In this work, we investigated Fe–Cu alloys to explore the effects of Cu concentration on the thermal stability of nanocrystalline samples. Using hybrid molecular dynamics(MD) and Monte Carlo(MC) simulations, annealing treatments of nanocrystalline samples with varied Cu concentrations were conducted. The simulation results revealed that Cu atoms tended to accumulate at GBs. Subsequently, the model with Cu segregation was subjected to mechanical creep loading at various temperatures. Through the analysis of atomic structure evolution during creep deformation, it was found that Cu segregation efficiently stabilizes GBs and restricts their movement. The present findings highlight that the thermal stability of nanocrystalline Fe–Cu alloys can be effectively improved by introducing suitable Cu segregation at GBs.

关键词： Nanocrystalline alloys Molecular dynamics simulations Grain boundary Thermal stability

Nano-capillary induced assemble of quantum dots on perovskite grain boundaries for efficient and stable perovskite solar cells

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能源化学:英文版 2023年第8期83卷 595-601,I0014页

作者： Miaoyu Lin Jingjing He Xinyi Liu Qing Li Zhanpeng Wei Yuting Sun Xuesong Leng Mengjiong Chen Zhuhui Xia Yu Peng Qiang Niu Shuang Yang Yu Hou Key Laboratory for Ultrafine Materials of Ministry of Education Shanghai Engineering Research Center of Hierarchical NanomaterialsShanghai Frontiers Science Center of Optogenetic Techniques for Cell MetabolismSchool of Materials Science and EngineeringEast China University of Science and TechnologyShanghai 200237China National Enterprise Technology Center Inner Mongolia Erdos Electric Power and Metallurgy Group Company LimitedOrdos 016064Inner MongoliaChina

In recent years, perovskite solar cells(PSCs) have propelled into the limelight owing to rapid development of efficiency;however, the abundant defects at the perovskite grain boundaries result in unwanted energy loss and structural degradation. Here, the grain boundaries of perovskite polycrystalline films have been found to act as nanocapillaries for capturing perovskite quantum dots(PQDs), which enable the conformal assemble of PQDs at the top interspace between perovskite grains. The existence of PQDs passivated the surface defects, optimized the interfacial band alignments, and ultimately improved the power conversion efficiency from 19.27% to 22.47% in inverted PSCs. Our findings open up the possibility of selective assembly and structural modulation of the perovskite nanostructures towards efficient and stable PSCs.

关键词： Perovskite solar cells Quantum dots Capillarity Grain boundary Passivation

Atomistic Simulation of Interaction between Grain boundary and Dislocations in Ni_3Al

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Journal of Materials Science & Technology 1993年第5期9卷 327-337页

作者： Dongliang LIN(T.L.Lin) Da CHEN Min LU Department of Materials Science,Shanghai Jiaotong University,Shanghai,200030,China Shanghai Jiaotong Univ Shanghai China

The embedded atom type potentials and static relaxation method combined with a steepest decent computational technique have been used to simulate the interaction between the Grain boundary (GB) and dislocations in Ni_3Al alloys.The focus has been placed on the energy feature of the interaction,the distortion of GB structural units,and the dislocation core structure near the GB.Im- plication has also been made on the results for the understanding of the mechanism responsible for B-enhanced ductility.

关键词： atomistic simulation Grain boundary dislocation Ni_3Al

Deformation and phase transformation mechanisms of 40Cr10Si2Mo steel during hot compression

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Journal of Iron and Steel Research(International) 2023年第4期30卷 760-771页

作者： Qing-juan Wang Qin-ren Wang Zhong-ze Du Ze-en He Xue Dang Ze-jiang Qi Cong-cong Yang School of Metallurgical Engineering Xi’an University of Architecture and TechnologyXi’an 710055ShaanxiChina

Thermo-mechanical experiments on martensitic heat-resistant 40Cr10Si2Mo steel were conducted using a Gleeble simulator in temperature and strain rate ranges of 1073–1373 K and 0.1–20 s^(-1),respectively.Processing maps were developed and correlated with deformed microstructures based on the dynamic material model theory.The analysis of the maps revealed that both applied temperature and strain rate had significant effects on the power dissipation efficiency and flow instability of the steel alloy.Electron backscatter diffraction analysis was also implemented to study the effect of deformation conditions on martensitic morphology.The results showed that higher temperatures and strain rates led to a fine martensitic packet,and the martensite lath increased in width at high temperatures.Two deformation domains,which exhibit different recrystallization processes,were recognized.The discontinuous dynamic recrystallization(DRX)mechanism in the low strain rate domain was characterized by the migration and growth of high-angle grains during straining.In contrast,in the high strain rate domain,the development of new grain boundaries is primarily associated with the deformation microbands in the low-temperature deformation domain.As the temperature increased,the high dislocation density accelerated the migration of the grain boundaries.Furthermore,the DRX mechanism changed from continuous DRX to post-DRX.This change in the DRX mechanism type was attributed to the time during which the sample remained high temperature after deformation.

关键词： 40Cr10Si2Mo steel Dynamic recrystallization DRX mechanism Grain boundary Dislocation density

Toward developing Ti alloys with high fatigue crack growth resistance by additive manufacturing

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Journal of Materials Science & Technology 2023年第1期132卷 166-178页

作者： F.Wang L.M.Lei X.Fu L.Shi X.M.Luo Z.M.Song G.P.Zhang Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China AECC Commercial Aircraft Engine Co. Ltd.Shanghai 201306China

Fatigue crack growth behaviors were investigated by three-point bending tests for TA19 alloy fabricated by laser metal deposition and four kinds of heat-treated samples.The crack growth resistance of the TA19 samples in the near-threshold regime and Paris regime was evaluated through the experimental characterization and theoretical analysis of the interaction between fatigue crack andα/βphase inter-face,columnar prior-βGrain boundary and colony boundary.The results show that in the near-threshold regime,the fatigue crack propagation threshold and resistance increase with the increase of widths of lamellarαp phases and colonies,and the decrease of the number ofαlaths with an angle(ϕ)relative to the applied stress direction ranging from 75°to 90°.In the Paris regime,the fatigue cracking path can be deflected at colony boundaries or columnar prior-βgrain boundaries.The larger the deflection angle,the more tortuous the cracking path and the lower the fatigue crack growth rate.The angle(γ)of the columnar prior-βgrain growth direction relative to the build direction affects not onlyϕof differentαvariants,but also the fatigue cracking path deflection angle(θij)at columnar prior-βgrain boundaries.An optimal combination ofγ=0°-15°-0°-15°for several adjacent columnar prior-βgrains is derived from the theoretical analysis,and that can effectively avoidϕbeing in the range from 75°to 90°and makeθij as large as possible.Such findings provide a guide for the selection of scanning strategies and process parameters to additively manufacture Ti alloys with high fatigue damage tolerance.

关键词： Ti alloy Fatigue crack growth Additive manufacturing Phase interface Grain boundary

Effects of Nd-Ga intergranular addition on microstructure and magnetic properties of heavy-rare-earth-free Nd-Fe-B sintered magnets

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Journal of Rare Earths 2022年第6期40卷 924-929,I0003页

作者： Jinhao Zhu Guangfei Ding Lei Jin Zhehuan Jin Bo Zheng Shuai Guo Renjie Chen Aru Yan CAS Key Laboratory of Magnetic Materials and Devices and Zhejiang Province Key Laboratory of Magnetic Materials and Application TechnologyNingbo Institute of Materials Technology and EngineeringChinese Academy of SciencesNingbo 315201China University of Chinese Academy of Sciences Beijing 100049China

In this study,we propose an approach of Grain boundary modification that can significantly increase the coercivity of the B-lean Nd-Fe-B sintered magnets by intergranular addition of Nd-Ga.The coercivity is substantially enhanced from 1.51 to 2.04 T through optimizing the microstructure and adjusting the phase composition for the Grain boundary phase in the annealed magnets.The matrix grains are covered by a continuous thin Grain boundary phase accompanying the formation of intermetallic Nd_(6)Fe_(13)Ga phases.The analysis of magnetic behaviors above Curie temperature confirms that the Grain boundary phase of annealed Nd-Ga doped magnets appears to be non-ferromagnetic,facilitating the intergrain exchange decoupling.Microstructure observation in Grain boundary area indicates that some surface of the matrix grain is dissolved in the formation process of the Nd_(6)Fe_(13)Ga phase.It gives rise to a decrease in the proportion of matrix grains and saturation magnetization of the magnet.The detailed relationship between magnetic properties and microstructure is discussed based on these results.

关键词： Nd-Fe-B sintered Magnet Magnetic properties Grain boundary Microstructures Rare earths

Dissociation of Tilt Dislocation Walls in Au

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Acta Metallurgica Sinica(English Letters) 2022年第11期35卷 1787-1792页

作者： Yu-Juan Geng Chun-Yang Wang Jing-Xin Yan Zhen-Jun Zhang Hua-Jie Yang Jin-Bo Yang Kui Du Zhe-Feng Zhang Shi-Changxu Innovation Centerfor Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering Chongqing Jiaotong UniversityChongqing 400074China

The movement or dissociation of dislocations is signifi cantly important for better understanding the plastic deformation mechanisms and mechanical properties of metals.It is commonly believed that a dislocation/2 in Au is easy to dissociate into a pair of Shockley partial dislocations/6 due to low stacking fault energy(SFE).Contrary to this prevailing perception,the present atomistic modeling demonstrates that this reaction could be completely suppressed when dislocations/2 are grouped into tilt walls,consistent with our experimental observations.Such phenomenon is actually the extreme case accompanying with the variation of Burgers vectors of partials with tilt angle,as revealed by a series of simulations,from which it is clearly seen that the Burgers vectors of partials deviate considerably from that of Shockley partials,enormously depending on the tilt angle.Our fi ndings could facilitate a better understanding on many phenomena and properties of face-centered cubic metals(FCC).

关键词： Dislocation Tilt wall Stacking fault Dissociation Grain boundary

Effect of boron addition on microstructure and mechanical properties of an additively manufactured superalloy

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Journal of Iron and Steel Research(International) 2023年第3期30卷 601-609页

作者： Rui Wang Dao-hong Wang Peng Zhang Zhi-qing Yang Jing-jing Liang Jin-guo Li Shi-Changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016LiaoningChina School of Materials Science and Engineering University of Science and Technology of ChinaHefei 230026AnhuiChina Jiang Su Feiyue Machine and Pump Group Co. Ltd.Jingjiang 225300JiangsuChina

The effect of boron addition(0.010,0.015,and 0.020 wt.%)on the microstructure and mechanical properties of an additively manufactured superalloy was examined.The as-built microstructure was investigated by scanning electron microscopy and transmission electron microscopy.The results demonstrate that boron precipitates as M_(3)B_(2)boride at the Grain boundary.The increase in boron content increases the amount ofγ/γ′eutectic and the size and fraction of M_(3)B_(2)boride.Boron creates nanoscale fine borides at grain boundaries,which significantly reinforces grain boundaries.The mechanical property analysis indicated that the addition of boron improved the tensile ductility at 760℃and stress rupture properties at 760℃/780 MPa.However,with the excessive addition of boron,the mechanical property was reduced.

关键词： Additive manufacturing Superalloy Boron Grain boundary Stress rupture Tension