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Journal of Magnesium and Alloys 2024年第5期12卷 1841-1853页

作者： M.Lv H.L.Ge Q.Q.Jin X.H.Shao Y.T.Zhou B.Zhang X.L.Ma Shenyang national Laboratory for materials Science Institute of Metal Research Chinese Academy of Sciences School of materials Science and Engineering University of Science and Technology of China materials Science and Engineering Research center Guangxi University of Science and Technology

In-situ electron irradiation and aging are applied to introduce high-density precipitates in an Mg-10Gd-3Y-1Zn-0.5Zr(GWZ1031K, wt.%)alloy to improve the hardness. The results show that the hardness of the Mg alloy after irradiation for 10 h and aging for 9 h at 250 ℃ is 1.64 GPa, which is approximately 64% higher than that of the samples before being treated. It is mainly attributed to γ' precipitates on the basal plane after irradiation and the high-density nanoscale β' precipitates on the prismatic plane after aging, which should be closely related to the irradiation-induced homogenous clusters. The latter plays a key role in precipitation hardening. This result paves a way to improve the mechanical properties of metallic materials by tailoring the precipitation through irradiation and aging.

关键词： Mg alloy Electron beam irradiation Hardening Precipitates In-situ TEM

Flow characterization of macroporous W-4.8 vol.%ZrO2 alloy during hot deformation with improved constitutive equation and processing maps

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Tungsten 2024年第3期6卷 610-620页

作者： Jia-Hao Ye Liu-Jie Xu Ji-Kang Hu School of materials Science and Engineering Henan University of Science and Technology national Joint Engineering Research center for Abrasion Control and Molding of metal materials Henan University of Science and Technology

In this work,isothermal compression experiments of macroporous W-4.8 vol.%ZrO2（W-4.8ZrO2） at 1300-1600℃ and strain rate of 0.005-1 s-1were carried out on a Gleeble-1500D thermo-mechanical simulator.The dynamic recovery of W-4.8ZrO2is the main "softening" mechanism.On the basis of Arrhenius model,the initial constitutive equation is established by exploring the influence of temperature,strain rate and rheological stress.Based on Arrhenius model,the relationship between flow stress,strain rate and deformation temperature is established.Considering the influence of strain,the improved constitutive equation and the law of material constant changing with the strain are obtained.After that,the hot processing maps were drawn on the basis of the dynamic material model,which is used to analyze the instability mechanism of the W-4.8ZrO2,and determine the appropriate hot working process parameters(temperature:1350-1450℃,strain rate:0.1-1 s-1).

关键词： Tungsten alloy Flow characteristics Constitutive equation Hot processing maps

Cerium refinement of grains and primary carbides during solidification of Cr_(4)Mo_(4)V bearing steel

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Journal of Rare Earths 2024年第4期42卷 783-792页

作者： Weifeng Liu Jianqiang Wang Mingyue Sun Bin Xu Jiahao Yao Qunbo Fan Dianzhong Li Chongqing Innovation center Beijing Institute of TechnologyChongqing401135China Shenyang national Laboratory for materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang110016China

The effect of cerium(Ce)on the solidification microstructure of Cr_(4)Mo_(4)V bearing steel was investigated via a combined experimental and theoretical method.With a trace amount(0.056 wt%)of Ce addition,the coarse columnar grains in as-cast microstructure transform into equiaxed ones,and the average diameter is reduced from 56 to 27μm.The network-like and bulky primary MC and M2C carbides at the interdendritic regions become disconnected and refined,and their volume percentage decreases from4.15 vol%to 2.1 vol%.Ce-inclusions acting as heterogeneous nucleation agents of prior-austenite grains and Ce atoms segregating at grain boundaries,both contribute to the refinement of grains.Thermodynamic calculations reveal that primary carbides are precipitated afterγ-austenite forms near the end of the solidification process.The modification of primary carbides in size and amount is mainly attributed to the isolated remaining melt separated by refinedγ-austenite grains in which the nucleation of carbides is promoted,while the growth is restrained owing to the less segregation of alloying elements.

关键词： Cr_(4)Mo_(4)V bearing steel Rare Earths Grains Primary carbides Refinement

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EBSD analysis of grain boundary evolution and dynamic recrystallization of Inconel 625 superalloy at various hot spinning feed rates

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Progress in Natural Science:materials International 2024年第1期34卷 56-65页

作者： Zhanjie Jing Jiangkun Fan Xudong Liu Yuelin Song Zixiao Wang Kai Cao Yuetan Chen Heng Fu Jianing Zhang Jinshan Li State Key Laboratory of Solidification Processing Northwestern Polytechnical University Chongqing Innovation center Northwestern Polytechnical University national&Local Joint Engineering Research center for Precision Thermoforming technology of Advanced metal materials

Hot spinning can make the material withstand shear stress, so that the shape of the material has a great change,which is one of the main processing methods of nickel-based alloy plate members. Inconel 625 alloy, which has excellent high temperature mechanical properties and can be used as the main candidate material for aerospace applications, needs further study on its hot spinning deformation behavior and deformation mechanism. In this paper, the effect of feed rate on the microstructure evolution of Inconel 625 superalloy was studied by the electron backscattered diffraction technology. The microstructure with necklace-like structures composed of dynamic recrystallization(DRX) grains was observed after hot spinning. It was found that at the low feed rate, the promotion of DRX degree and grain refinement happened, where the grain size reached the trough of 10.99 μm under a feed rate of 300 mm/min. However, with the further feed rate rising, the degree of DRX was suppressed to a certain extent and grain size increased to 14.26 μm. On balance, the feed rate of 300 mm/min was the most efficient condition for grain refinement. Besides, it was revealed that both discontinuous dynamic recrystallization(DDRX) and continuous dynamic recrystallization(CDRX) occurred during hot spinning. DDRX includes the initial grain boundary nucleation by bulging and the annealing twin boundary assisted nucleation, while the CDRX mechanism is related to the continuous subgrain rotation within the deformed grain. DDRX is the main DRX mechanism.

关键词： Inconel 625 superalloy Hot spinning Grain boundary evolution DRX mechanism

Effect of Ga on the microstructure and properties of NiCoV alloy at different annealing temperatures

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Progress in Natural Science:materials International 2024年第2期34卷 408-419页

作者： Jin Li Peng Wang Lvxing Chen Meifeng He Jun Cheng School of materials and Chemistry University of Shanghai for Science and Technology Northwest Institute for Nonferrous metal Research Shaanxi Key Laboratory of Biomedical Metal Materials

To obtain a high-entropy alloy characterized by high strength and plasticity,（NiCoV）100-xGaxx=0,5,7) was successfully prepared,cold-rolled,and heat-treated.The microstructure was analyzed to correlate Ga content with the performance of the system.The addition of Ga can produce alloying effects,including solid solution strengthening effect,second phase precipitation strengthening effect,and layer misalignment energy reduction effect.The experimental results show adding Ga elements can enrich Ni,Co,V,and Ga above the grain boundaries,causing the alloy to produce annealed twins inside.The alloy is strengthened mainly by precipitation,and the formation of the precipitation phase effectively enhances the strength of the alloy.The low stacking fault energy promotes the toughening of NiCoV but makes the plasticity of the alloy decrease.Still,the formation of annealed twins effectively increases the plasticity,which makes the alloy harder but does not reduce the plasticity too much.By comparing the experimental properties,（NiCoV）93Ga7showed the best mechanical properties at the annealing temperature of 900℃,yield strength,tensile strength and elongation of 906 MPa,1321 MPa and21.36 %,respectively.

关键词： Annealing treatment High entropy alloy Mechanical properties Precipitation strengthening Twin strengthening

An efficient CuZr-based metallic glasses electrode material for electrocatalytic degradation of azo dyes

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Journal of Environmental Sciences 2024年第2期136卷 537-546页

作者： Zhiwang Deng Bowen Zhao Songtao Li Zhengkun Li Shiming Zhang Kewei Zhang Zhengwang Zhu Taiyuan University of Science and technology School of materials science and engineeringTaiyuan 030024China Shi-changxu Innovation center for Advanced materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Chinese Academy of Sciences Key Laboratory of Nuclear materials and Safety Assessment Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Qingdao Yunlu Advanced materials technology Co. Ltd.Qingdao 266232China

metallic glasses have received a lot of attention on wastewater treatment due to their unique atomic structure,and the use of metallic glasses as electrodes has produced unexpected electrocatalytic degradation effects for many pollutants through combining with electrochemical technology.However,it still is a formidable challenge to find a metallic glass electrode material with both efficient and clean for the catalytic degradation of pollutants.In this work,the Cu_(55)Zr_(45)metallic glassy ribbons are used as an electrode to degrade azo dyes and show the excellent degradation effect,which can reach 95.6%within 40 min.In the degradation process,almost no additives are produced and Cu_(55)Zr_(45)metallic glassy ribbons have excellent effects under different pH conditions.Meanwhile,it exhibits good stability for degradation efficiency during the 8 cycle degradation tests of the amorphous alloy electrode.When the copper nanoparticles are exposed on the surface of the ribbons,the oxidized copper obtained synergistically produce activated radicals is the primary degradation mechanism,where the auxiliary degradation mechanisms include electron transfer and the promotion of active chlorine.This research develops a new type of electrode material for wastewater treatment,and the economy and high efficiency of Cu55Zr45metallic glass endow it the expandable functional applications.

关键词： metallic glasses Azo dyes Electrocatalytic Degradation Oxidized copper

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Coercivity mechanism of La-Nd-Fe-B films with Y spacer layer

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Chinese Physics B 2024年第3期33卷 138-143页

作者：马俊赵晓天刘伟李阳刘龙赵新国张志东 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

The effect of the Y spacer layer on the phase composition,coercivity,and magnetization reversal processes of La-Nd-Fe-B films has been investigated.The addition of a 10 nm Y spacer layer increases the coercivity of the film to 1.36 T at 300 K and remains 0.938 T at 380 K.As the thickness of the Y spacer layer increases,Y participates in the formation of the main phase in the film,and further regulates the formation of La-B phases.The results of the first-order reversal curve(FORC)and micromagnetic fitting show that the coercivity of all the films is dominated by nucleation mechanism.The c-axis preferred orientation,good magnetic microstructure parameters and the largest dipole interaction enhance the coercivity.Therefore,the introduction of the Y spacer layer can be an effective way to improve the coercivity of La-Nd-Fe-B film over a wide temperature range of 150 K-380 K.

关键词： La-Nd-(Y)-Fe-B films magnetization reversal mechanisms coercivity multilayers

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A new insight into LPSO phase transformation and mechanical properties uniformity of large-scale Mg-Gd-Y-Zn-Zr alloy prepared by multi-pass friction stir processing

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Journal of Magnesium and Alloys 2024年第5期12卷 2041-2056页

作者： Xiaohu Guan Wen Wang Ting Zhang Pai Peng Qiang Liu Peng Han Ke Qiao Jun Cai Liqiang Wang Kuaishe Wang School of metallurgical Engineering National and Local Joint Engineering Research Center for Functional Materials Processing Xi'an University of Architecture and Technology Xi'an Rare metal materials Institute Co.Ltd State Key Laboratory of metal Matrix Composites School of Material Science and Engineering Shanghai Jiao Tong University

A large-scale fine-grained Mg-Gd-Y-Zn-Zr alloy plate with high strength and ductility was successfully prepared by multi-pass friction stir processing(MFSP) technology in this work. The structure of grains and long period stacking ordered(LPSO) phase were characterized,and the mechanical properties uniformity was investigated. Moreover, a quantitative relationship between the microstructure and tensile yield strength was established. The results showed that the grains in the processed zone(PZ) and interfacial zone(IZ) were refined from 50 μm to 3 μm and 4 μm, respectively, and numerous original LPSO phases were broken. In IZ, some block-shaped 18R LPSO phases were transformed into needle-like 14H LPSO phases due to stacking faults and the short-range diffusion of solute atoms. The severe shear deformation in the form of kinetic energy caused profuse stacking fault to be generated and move rapidly, greatly increasing the transformation rate of LPSO phase. After MFSP, the ultimate tensile strength, yield strength and elongation to failure of the large-scale plate were 367 MPa, 305 MPa and 18.0% respectively. Grain refinement and LPSO phase strengthening were the major strengthening mechanisms for the MFSP sample.In particularly, the strength of IZ was comparable to that of PZ because the strength contribution of the 14H LPSO phase offsets the lack of grain refinement strengthening in IZ. This result opposes the widely accepted notion that IZ is a weak region in MFSP-prepared large-scale fine-grained plate.

关键词： Friction stir processing Multi-pass Mg-Gd-Y-Zn-Zr alloy LPSO phase transformation Mechanical properties

Enhanced memristor performance via coupling effect of oxygen vacancy and ferroelectric polarization

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Journal of materials Science & technology 2024年第4期171卷 139-146页

作者： Zhi Yun Yue Zhi Dong Zhang Zhan Jie Wang 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 School of materials Science and Engineering Shenyang University of TechnologyShenyang 110870China

As a new type of nonvolatile memory,the resistive memristor has broad application prospects in in-formation storage and neural computing based on its excellent resistive switching(RS)performance.At present,it is still a great challenge to improve both ferroelectric polarization and leakage current to achieve a high RS on/offratio of ferroelectric memristors.Herein,epitaxial Pb(Zr_(0.40)Ti_(0.60))O_(3)(PZT)thin films with low content Ca doping were deposited on the Nb:SrTiO_(3)substrate to prepare PCZT/NSTO het-erostructures and their RS behaviors were studied.The research findings show that compared with pure PZT film,the ferroelectric polarization of 1-mol%-Ca-doped PZT film is slightly improved,while the leak-age current is increased by three orders of magnitude.Therefore,the RS on/offratio reaches 2.5×10^(5),about three orders of magnitude higher than pure PZT films.The theoretical analysis reveals that the RS behavior of PCZT/NSTO heterostructures is controlled by the PCZT/NSTO interfacial barrier and the space charge-limited current mechanism.Our results demonstrate that the ferroelectricity and electricity of ferroelectric thin films can be improved simultaneously by doping low-content Ca ions to increase the RS performance,which provides a good reference for the development of high-performance ferroelectric memristor devices.

关键词： Ferroelectric memristor Ca-doped PZT Ferroelectric polarization Oxygen vacancies Resistive switching

First-principles study on the electronic structure of Pb_(10−x)Cu_(x)(PO_(4))_(6)O(x=0,1)

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Journal of materials Science & technology 2024年第4期171卷 66-70页

作者： Junwen Lai Jiangxu Li Peitao Liu Yan Sun Xing-Qiu Chen 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

Recently,Lee et al.claimed the experimental discovery of room-temperature ambient-pressure super-conductivity in a Cu-doped lead-apatite(LK-99)(arXiv:2307.12008,arXiv:2307.12037).Remarkably,the claimed superconductivity can persist up to 400 K at ambient pressure.Despite the experimental im-plication,the electronic structure of LK-99 has not yet been studied.Here,we investigate the electronic structures of LK-99 and its parent compound using first-principles calculations,aiming to elucidate the doping effects of Cu.Our results reveal that the parent compound Pb_(10)(PO_(4))_(6)O is an insulator,while Cu doping induces an insulator-metal transition and thus volume contraction.The band structures of LK-99 around the Fermi level are featured by a half-filled flat band and a fully-occupied flat band.These two very flat bands arise from both the 2p orbitals of 1/4-occupied O atoms and the hybridization of the 3d orbitals of Cu with the 2p orbitals of its nearest-neighboring O atoms.Interestingly,we observe four van Hove singularities on these two flat bands.Furthermore,we show that the flat band structures can be tuned by including electronic correlation effects or by doping different elements.We find that among the considered doping elements(Ni,Cu,Zn,Ag,and Au),both Ni and Zn doping result in the gap opening,whereas Au exhibits doping effects more similar to Cu than Ag.Our work establishes a foundation for fu-ture studies to investigate the role of unique electronic structures of LK-99 in its claimed superconducting properties.

关键词： First-principles calculations Density functional theory Electronic structur e Superconductivity Flat bands Strongly correlated electrons