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Ultra-stable metal nano-catalyst synthesis strategy:a perspective

Rare Metals 2020年第2期39卷 113-130页

作者： Xiao-qing Cao Jun Zhou Song Li gao-wu qin Key Laboratory for Anisotropy and Texture of Materials School of Materials Science and EngineeringNortheastern UniversityShenyang 110819China

Supported metal nanoparticles(NPs)as an important heterogeneous catalyst have been widely applied in various industrial *** the catalytic reaction,size of the particles plays an important role in determining their catalytic ***,the small particles exhibit superior catalytic activity in comparison with the larger particles because of an increase in lowcoordinated metal atoms on the particle surface that work as active sites,such as edges and corner ***,these small NPs are typically unstable and tend to migrate and coalescence to reduce their surface free energy during the real catalytic processes,particularly in high-temperature ***,a means to fabricate stable small metal NP catalysts with excellent sinter-resistant performance is necessary for maintaining their high catalytic *** this study,we have summarized recent advances in stabilizing metal NPs from two aspects including thermodynamic and kinetic *** former mainly involve preparing uniform NPs(with an identical size and homogeneous distribution)in order to restrain Ostwald ripening to achieve stability,while the latter primarily involves fixing metal NPs in some special confinement materials(e.g.,zeolites,mesoporous silica and mesoporous carbons),encapsulating NPs using an oxide-coating film(e.g.,forming core-shell structures),or constructing strong metal-support interactions to improve *** the end of this review,we highlight our recent work on the preparation of high-stability metal catalysts via a unique interfacial plasma electrolytic oxidation technology,that is,metal NPs are well embedded in a porous MgO layer that has both high thermal stability and excellent catalytic activity.

关键词： Nano-catalysts Thermal stability Sinterresistant Synthesis strategy

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Improved corrosion resistance of dental Ti50Zr alloy with(TiZr)N coating in fluoridated acidic artificial saliva

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Rare Metals 2021年第10期40卷 2927-2936页

作者： Wen-Fang Cui Yang-Yang Dong Yong-Cun Bao gao-wu qin Key Laboratory for Anisotropy and Texture of Materials(Ministry of Education) School of Materials Science and EngineeringNortheastern UniversityShenyang 110819China

The electrochemical corrosion behavior of the dental Ti50 Zr alloy with and without nanocrystalline(TiZr)N coating was comparatively investigated in artificial saliva solutions with different pH values and fluoride ion concentrations. The chemical stability of the passive films on the coated and non-coated Ti50 Zr alloy was evaluated by calculating passive film thickness. The chemical compositions and valence structures of the passive films were analyzed by X-ray photoelectron spectroscopy(XPS). The results show that the(TiZr)N-coated alloy displays distinctly decreased corrosion rate and increased impedance compared with Ti50 Zr alloy in nonfluoridated and fluoridated acidic solutions. Particularly, in the solution of pH = 3.9 and 0.15% NaF-containing, the corrosion protection efficiency of(TiZr)N coating reaches90%. The excellent corrosion resistance of the coated alloy is attributed to that the nanocrystallines in(TiZr)N coating decreases micropores and crack defects, which strongly impedes the corrosive ions diffusion and electrode process at Ti substrate/coating interface. Meanwhile,(TiZr)N coating shows good passivation behavior in acidic solution and active–passive transition behavior in fluoridated acidic solution. The coated Ti50 Zr alloy with high chemical stability has potential application prospect for dental implants.

关键词： Dental material Titanium alloy Nitride coating Fluoride Corrosion

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Phase equilibria of low-Y side in Mg-Zn-Y system at 400℃

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Rare Metals 2020年第3期39卷 262-269页

作者： Bo-Shu Liu Hong-Xiao Li Yu-Ping Ren Min Jiang gao-wu qin Key Laboratory for Anisotropy and Texture of Materials Ministry of EducationNortheastern UniversityShenyang110819China

Phase equilibrium relations of the Mg-Zn-Y system in the low-Y side at 400℃were investigated by alloy-equilibrated method,combined with thermal *** results show that there is a liquid phase which could be in equilibrium with an a-Mg solid solution and an icosahedral quasicrystal I phase in the low-Y side of the Mg-Zn-Y system at 400℃.The liquid phase region originates from the binary Mg-Zn system and extends to 0.4 at%Y in the Mg-Zn-Y ***,the hexagonal structure H phase,fee W phase and LPSO phase(X phase)are in equilibrium with *** Y/Zn(atomic ratio,the same as follows)increasing,there exist four three-phase regions consisting of I+liquid+α-Mg,I+H+α-Mg,H+W+α-Mg and W+X+α-Mg,respectively,in the low-Y side of the isothermal section at 400℃.The twophase region a-Mg+I phase exists between I+H+aMg and I+liquid+*** this two-phase region,the Y/Zn ratio is in the range of 0.14-0.17;and a three-phase region of a-Mg+I phase+H phase appears when Y/Zn ratio comes up to *** I but W phase is in equilibrium with a-Mg,when Y/Zn ratio>*** system is in liquid-state phase equilibrium,when Y/Zn ratio<0.14.

关键词： Mg-Zn-Y system Phase equilibrium Icosahedral quasicrystal phase Solid solubility

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Phase equilibria of low-Ni side in Nb-Ni-Ti system at 1100℃

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Rare Metals 2020年第8期39卷 936-941页

作者： Hong-Xiao Li Zhi-Chao Li Yu-Ping Ren Min Jiang gao-wu qin Key Laboratory for Anisotropy and Texture of Materials Ministry of EducationNortheastern UniversityShenyang 110819China

The phase equilibria related to liquid phase in low-Ni side of Nb-Ni-Ti system at 1100℃were investigated through scanning electron microscope(SEM),electron probe micro-analyzer(EPMA),X-ray diffraction(XRD)and differential scanning calorimetry(DSC).The results show that there exists liquid phase in equilibrium with continuous solid solution(Nb,βTi)and compound TiNi in low-Ni side of Nb-Ni-Ti system at 1100℃.The liquid phase region originates from low-Ni side of binary TiNi system and extends to 9.4 at%Nb in isothermal section of Nb-Ni-Ti phase *** solid solubility of Nb in binary compound TiNi is about 10.6 at%.At 1100℃,there exist two three-phase regions consisting of liquid+(Nb,βTi)+TiNi and(Nb,βTi)+TiNi+X_B in Nb-Ni-Ti system,where X_B is the compound with hexagonal structure and composition of 32.8 Nb-44.5 Ni-22.7 *** wide two-phase region(Nb,βTi)+TiNi exists between these two three-phase *** this two-phase region,Ti content in continuous solid solution(Nb,βTi)varies from6.6 at%to 25.7 at%,but Ni content is almost the same,which is about 4.0 at%.The eutectic transformation L■(Nb,βTi)+TiNi takes place at about 1138℃in Nb-Ni-Ti ternary system.

关键词： Nb-Ni-Ti system Phase equilibrium Liquid phase Solid solubility

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Structures and macrosegregation of a 2024 aluminum alloy fabricated by direct chill casting with double cooling field

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China Foundry 2022年第1期19卷 1-8页

作者： Cheng Zhu Zhi-hao Zhao qing-feng Zhu gao-song Wang Yu-bo Zuo gao-wu qin Research Center for Metallic Wires School of Materials Science and EngineeringNortheastern UniversityShenyang 110819China Key Laboratory of Electromagnetic Processing of Materials Ministry of EducationNortheastern UniversityShenyang 110819China Key Laboratory of Anisotropy and Texture of Materials Ministry of EducationNortheastern UniversityShenyang 110819China

Central region coarse grains and centerline segregation are common defects in aluminum ingots fabricated by direct chill(DC)casting.A double cooling field was introduced into the DC casting process to reduce these defects,whereby the external cooling was supplied by the mold and water jets,and intercooling was achieved by inserting a rod of the same alloy into the molten pool along the central axis of the *** than forming a good metallurgical interface during solid-liquid compound casting,in the present work,the purpose of inserting the rod is to enforce internal cooling and consequently decrease the sump ***,the insertion provides more nucleation sites with the unmoltenα-Al *** structure and the macrosegregation of 2024 Al alloy ingots prepared by DC casting with and without the inserts were *** show that when the inserting position is 50 mm above the upper edge of the graphite ring,significant grain refinement in the central region of the ingot and a reduced centerline segregation are achieved.

关键词： aluminum alloy direct chill casting double cooling field grain refinement macrosegregation

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Constructing Ni_(4)W/WO_(3)/NF with strongly coupled interface for hydrogen evolution in alkaline media

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Rare Metals 2023年第12期42卷 3945-3951页

作者： Teng Zhang Yi-Hong Yu Chuang-Wei Liu gao-wu qin Song Li Key Laboratory for Anisotropy and Texture of Materials(MoE) School of Material Science and EngineeringNortheastern UniversityShenyang 110819China Liaoning Province Engineering Research Center for Technologies of Low-Carbon Steelmaking Northeastern UniversityShenyang 110819China

The pursuit of storing renewable electricity in chemical bonds has encouraged the effort toward developing efficient electrocatalysts for alkaline hydrogen ***,the additional step of water dissociation under alkaline conditions frequently limits the performance of electrocatalysts in alkaline ***,we synthesize Ni_(4)W/WO_(3) with a strongly coupled interface on the Ni foam(NF)by phase transition of NiWO_(4),to enhance the activity for alkaline hydrogen *** is discovered that the strong binding hydroxyl on WO_(3) sites facilitates the dissociation of water,which in turn promotes hydrogen evolution through the synergy effect of strong adsorption of H on Ni *** adsorption/desorption energy of Ni sites is further tuned by the formation of intermetallic *** to the three-dimensional structure and tailored composition,the Ni_(4)W/WO_(3)/NF electrocatalyst exhibits a low overpotential of 31 mV at a current density of10 mA·cm^(-2),with a Tafel slope of 38 mV·dec^(-1).This work provides new opportunities to modulate the catalytic performance of Ni-based electrocatalysts by signifying the metal-oxide interface.

关键词： alkaline interface adsorption

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Inter-granular exchange coupling and magnetic anisotropy of Ta/Ru/Co-23 at%Pt perpendicular thin films with different Ru underlayer thicknesses

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Rare Metals 2016年第6期35卷 463-470页

作者： Na Xiao Bo Yang Jian-Sheng Wang Song Li Yu-Ping Ren gao-wu qin Research Academy Northeastern University Shenyang 110819China Key Laboratory for Anisotropy and Texture of Materials (MoE) School of Materials Science and Engineering Northeastern University Shenyang 110819 China

In the present work, a series of Ta/Ru/Co- 23 at%Pt thin films with varied Ru underlayer thicknesses were fabricated by magnetron sputtering. All of the films show c-axis preferred orientation perpendicular to the film surface. The drop of c/a ratio and lattice expansion of Co- Pt layer with the increase in Ru underlayer thickness was revealed by X-ray diffraction （XRD）. The coercivity of the Ta/Ru/Co-Pt thin films increases drastically with Ru underlayer thickness increasing, due to the enhancement of effective magneto-crystalline anisotropy constant and exchange decoupling of magnetic nano-grains. The enhancement of effective magneto-crystalline anisotropy constant is ascribed to the lattice deformation of Co-Pt layer by mismatching the Ru layer and Co-Pt surface. Moreover, the exchange decoupling of magnetic nanograins is attributed to the further isolation of magnetic nano-grains.

关键词： Co-Pt Perpendicular recording media Crystallographic orientation Exchange coupling

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Microstructure,Mechanical Properties and Corrosion Behavior of Extruded Mg–Zn–Ag Alloys with Single-Phase Structure

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Acta Metallurgica Sinica(English Letters) 2018年第6期31卷 575-583页

作者： Hong Zhao Li-qing Wang Yu-Ping Ren Bo Yang Song Li gao-wu qin Key Laboratory for Anisotropy and Texture of Materials Ministry of EducationSchool of Materials Science and EngineeringNortheastern University

Mg–Zn–Ag alloys have been extensively studied in recent years for potential biodegradable implants due to their unique mechanical properties,biodegradability and *** the present study,Mg–3Zn-x Ag（wt%,x=0.2,0.5 and0.8）alloys with single-phase crystal structure were prepared by backward extrusion at 340°*** addition of Ag element into Mg–3Zn slightly influences the ultimate tensile strength and microstructure,but the elongation firstly increases from12%to 19.8%and then decreases from 19.8%to 9.9%with the increment of Ag *** tensile yield strength,ultimate tensile strength and elongation of Mg–3Zn–0.2Ag alloy reach up to 142,234 MPa and 19.8%,respectively,which are the best mechanical performance of Mg–Zn–Ag alloys in the present *** extruded Mg–3Zn–0.2Ag alloy also possesses the best corrosion behavior with the corresponding corrosion rate of 3.2 mm/year in immersion test,which could be explained by the single-phase and uniformly distributed grain structure,and the fewer twinning.

关键词： Mg–Zn–Ag Single phase Backward extrusion Mechanical performance Corrosion behavior

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Microstructure,Mechanical Properties and Fracture Behavior of As-Extruded Zn-Mg Binary Alloys

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Acta Metallurgica Sinica(English Letters) 2017年第10期30卷 931-940页

作者： Li-qing Wang Yu-Ping Ren Shi-Neng Sun Hong Zhao Song Li gao-wu qin Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education) School of Materials Science and EngineeringNortheastern University

In the present work, Zn-（0-1）Mg（wt%） alloys were prepared by casting and indirect extrusion at 200 and300 ℃, respectively. With Mg addition, both the size and amount of second phase Mg2Zn（11） increased, and the equiaxed grains were significantly refined. The extrusion temperature had little influence on Mg2Zn（11）, but the grains were refined at low extrusion temperature. For the alloys extruded at 200 ℃, as Mg content increased, the tensile yield strength（TYS）increased from 64 MPa for pure Zn to 262 MPa for Zn-1Mg; the elongation increased from 14.3% for pure Zn to 25% for Zn-0.02Mg and then decreased to 5% for Zn-1Mg. For the alloys extruded at 300 ℃, as Mg content increased, the TYS increased from 67 MPa for pure Zn to 252 MPa for Zn-1Mg, while the elongation decreased from 11.7% to 2%. The alloy extruded at 200 ℃ exhibited higher TYS and elongation than the corresponding alloy extruded at 300 ℃. The combination of grain refinement and second phase Mg2Zn（11） contributed to the improvement in the TYS, and the grain refinement played a major role in strengthening alloy. Zn-0.02Mg and Zn-0.05Mg alloys extruded at 200 ℃ show a mixture of cleavage and ductile fracture corresponding to higher elongation, while the other alloys show cleavage fracture.

关键词： Zn-Mg binary alloy Indirect extrusion Microstructure Mechanical property Fracture behavior

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Microstructures and bio-corrosion resistances of as-extruded Mg-Ca alloys with ultra-fine grain size

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Rare Metals 2023年第2期42卷 680-687页

作者： Zi-Ren Xie Cheng Zhang Hu-Cheng Pan Yu-Xin Wang Yu-Ping Ren gao-wu qin Key Laboratory for Anisotropy and Texture of Materials(Ministry of Education) Northeastern UniversityShenyang110819China

Electrochemical and immersion tests were conducted to characterize the bio-corrosion resistance of asextruded Mg-Ca binary alloys with submicron grain *** microstructures were further characterized by optical microscopy(OM),scanning electronic microscopy and transmission electron microscope(TEM).The grain size was estimated from OM and TEM *** samples and at least 20 images were used to evaluate the average grain ***-textures of the as-extruded samples were measured via X-ray *** Mg-2Cu alloy extruded at 300℃(2Ca-300)exhibits the lowest current density of 1.683 mA·cm^(-2)and corrosion rate of 22.14 g·m^(-2)·day^(-1)in simulated body fluid,which is comparable with that of pure *** Ca addition can reduce grain size of as-extruded Mg alloy and decrease the corrosion *** formed Mg2Ca phases would accelerate the local galvanic corrosion and protect theα-Mg matrix simultaneously due to the lower electrode *** lower defect density,finer grain size and weaker basal texture intensity contribute to the excellent bi-corrosion resistance of the 2Ca-300 alloy.

关键词： Magnesium alloys Corrosion Defects Grain size

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