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Acta Metallurgica Sinica(English letters) 2007年第3期20卷 199-204页

作者： z.h. zou x.M. Yu b.S. zhang Y. Qi School of Science Northeastern University Shenyang 110004 China

A reactive co-deposition processing for obtaining high-quality single-phase bi2Sr2Cax-1CuxOy （bi2212） thin films has been investigated using molecular beam epitaxy （MbE） with 2.7 ×10^-3pa ozone gas introduction for oxidation. The thin films with a constant composition of almost 2 ： 2 ： 1 ： 2 were designed to be fabricated at the substrate temperature between 675 and 780℃, the substrate temperature dependence of the surface morphology and the emergence phases were investigated in detail. A noticeable result is that the distribution of Cu element in the thin films is sensitively changed with the substrate temperature. At 750℃ it is inclined to locate in the periphery of each grain through the diffusion process. At 780℃ the Cu-compositional fluctuation brought around the dendritic crystal growth in the thin films. below 705℃, the bi2212 single-phase cannot be achieved in the thin films.

关键词： bi2212 (bi2Sr2Cax-1CuxOy) single-phase dendritic growth substrate temperature

Derimorphisms over Algebras and Applications

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代数集刊:英文版 2023年第2期30卷 193-204页

作者： x.Cao S.h.liu x.S.lu z.J.Ye z.R.Yu Y.h.zhang School of Mathematical Sciences Shanghai Jiao Tong University 800 Dongchuan RoadShanghai 200240China MoE Key lab of Scientific and Engineering Computing Shanghai Jiao Tong University 800 Dongchuan RoadShanghai 200240China

The new concept"derimorphism"generalizing both derivation and homomor-phism is *** a derimorphism is invertible,its inverse is a Rota-baxter *** general theory of derimorphism is *** classification of all derimorphisms over an associative unital algebra is *** to the nonexistence of nontriv-ial positive derivations,it is shown that nontrivial positive derimorphisms do exist over any pair of opposite orderings over R[x],the lattice-ordered full matrix algebra and upper triangular matrix algebra over a totally ordered field.

关键词： derimorphism Rota-baxter operator opposite orderings positive derimor-phism

Towards the diffusion source cost reduction for NdFeb grain boundary diffusion process

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Journal of Materials Science & Technology 2020年第1期36卷 50-54页

作者： h.x.zeng z.W.liu J.S.zhang x.F.liao h.Y.Yu School of Materials Science and Engineering South China University of TechnologyGuangzhou 510640China

Aiming at improving the performance/cost ratio in grain boundary diffusion process(GbDP),the critical RE containing Pr-Al-Cu alloy,less expensive RE containing la-Al-Cu alloy and non-RE Al-Cu alloy were employed as the diffusion *** preliminary results show that the coercivity was successfully enhanced from 1000 kA/m to 1695,1156 and 1125 kA/m by Pr70Al20Cu10,la70Al20Cu10 and Al75Cu25(at.%) alloys diffusion,respectively,due to the formation of(Nd,Pr)-Fe-b,la2 O3 and c-Nd2 O3 phases respectively,after *** is also found that the corrosion resistance can be improved by Al-Cu diffusion due to the positive effects of Al and Cu elements in grain *** present results demonstrated the various coercivity enhancement mechanisms for the GbDP based on different diffusion sources,and provided feasible solutions for cost reduction of GbDP and NdFeb production by saving RE resource.

关键词： Grain boundary diffusion Cost reduction Coercivity Microstructure Corrosion resistance

A STuDY OF TEMPERATuRE-DEPENDENT VAlENCE bOND STRuCTuRE OF TITANIuM

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Acta Metallurgica Sinica(English letters) 2007年第1期20卷 27-34页

作者： x.b. li Y.Q. xie Y.z. Nie h.J. Peng h.J. Tao F.x. Yu College of Materials Science and Engineering Central South University Changsha 410083 China

On the basis of energy and shape method for the determination of the valence bond （ Vb ） structures of crystal, the valence bond structure of titanium is redetermined at room temperature and calculated in the whole temperature range of 0-1943K. The outer shell electronic distribution of Ti is ec^29907. （sc^0.4980 ＋ dc^2.4927） ef^1.0098 in crystal. The temperature dependences of the Vb structures of hcp and bcc phases are the same. The Vb structures of hcp and bcc phases monotonically increase or decrease with the increase in temperature, but show discontinuous changes at the phase-transformation temperature 1155K.

关键词： valence bond structure temperature titanium

Mechanical property and structural changes by thermal cycling in phase-separated metallic glasses

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Journal of Materials Science & Technology 2021年第19期78卷 144-154页

作者： Y.Tang h.b.xiao x.D.Wang Q.P.Cao D.x.zhang J.z.Jiang International Center for New-Structured Materials(ICNSM) Laboratory of New-Structured MaterialsState Key Laboratory of Silicon Materialsand School of Materials Science and EngineeringZhejiang UniversityHangzhou310027China State Key laboratory of Modem Optical Instrumentation Zhejiang UniversityHangzhou.310027China

Nondestructive cryogenically thermal cycling has been a simple but effective treatment to enhance mechanical properties of glassy ***,how the structural heterogeneities on nanometer scales are affected by thermal cycling is still an ***,we report the response of spatial heterogeneities in three selected Ti_(41)zr_(25)be_(28)Fe_(6),zr_(56)Co_(14)Cu_(14)Al_(16)and zr_(42)Y_(14)Co_(22)Al_(22)(at.%)metallic glasses(MGs)with different compositions to the thermal cycling,which show significantly different structure and properties after the same treatments and could be ascribed to the joint contribution of relaxation and rejuvenation induced by thermal *** rejuvenation is initially prevailed in a zr-Y-containing MG,whereas the relaxation is dominant in a Cu-Co-containing MG,both eventually entering into a dynamic equilibrium *** employing nanometer-scale structural models,the intrinsic correlation between the spatial heterogeneity and thermal cycling is *** discovery could provide the fundamental understanding of the role of spatial heterogeneity in influencing the macroscopic properties of MGs via thermal cycling and help design high-performance glassy materials by tailoring their atomic structures with suitable thermal treatments.

关键词： Thermal cycling Metallic glass Spatial heterogeneity Relaxation Rejuvenation

Solid solution strengthening of high-entropy alloys from first-principles study

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Journal of Materials Science & Technology 2022年第26期121卷 105-116页

作者： h.l.zhang D.D.Cai x.Sun h.huang S.lu Y.z.Wang Q.M.hu l.Vitos x.D.Ding State Key laboratory for Mechanical behavior of Materials Frontier Institute of Science and TechnologyXi’an Jiaotong UniversityXi’an 710049China Key laboratory of Shaanxi Province for Craniofacial Precision Medicine Research College of StomatologyXi’an Jiaotong UniversityXi’an 710049China Department of Materials Science and Engineering The Ohio State University2041 College RoadColumbusOH 43210United States Institute of Metal Research Chinese Academy of SciencesShenyang 110016China Science and Technology on Surface Physics and Chemistry laboratory Jiangyou 621908China Applied Materials Physics Department of Materials Science and EngineeringRoyal Institute of TechnologyStockholm SE-10044Sweden

Solid solution strengthening(SSS)is one kind of strengthening mechanisms and plays an important role in alloy design,in particular for single-phase alloys including high-entropy alloys(hEAs).The classical labusch–Nabarro model and its expansions are most widely applicable to treating SSS of solid solution alloys including both conventional alloys(CAs)and *** this study,the SSS effects in a series of Febased CAs and hEAs are investigated by using the classical labusch–Nabarro model and its *** size misfit and shear modulus misfit parameters are derived from first-principles *** on available experimental data in combination with empirical SSS model,we propose fitting constants(i.e.,the ratio between experimental hardness and predicted SSS effect)for these two families of *** predicted host/alloy family-dependent fitting constants can be used to estimate the hardness of these SSS *** agreement between predicted and measured hardness values is satisfactory for both CAs and hEAs,implying that the proposed approach is reliable and successful.

关键词： Alloys Solid solution strengthening hardness Size misfit parameter Shear modulus misfit parameter First-principles calculations

Oxygen and Nitrogen Effects on MC Carbide in K465 Nickel-base Superalloy

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稀有金属材料与工程 2009年第A3期38卷 13-16页

作者： Wang l N zheng Q Sun x F Guan h R hu z Q Institute of Metals Research Chinese Academy of Sciences Shenyang 110015 China

Effects of oxygen and nitrogen on MC carbide in nickel-base superalloy K465 were investigated, because neither of the two gas elements was found to decide MC carbide morphology monotonically. The morphology of MC carbide under alloy solidified in conventional investment casting condition was observed to transform from script-type to block-type with the total oxygen and nitrogen content (gas content) in samples rising up from 1.2×10-6 mol/g to 2.6×10-6 mol/g. The area fraction and composition of the MC carbide also varied with increase of gas content. however, the morphology of MC carbide kept to be script-type even when gas content was up to 3.4×10-6 mol/g in samples solidified with a much higher cooling rate. These results indicate that effects of gas content on formation of MC carbide can be observed in specimens solidified with low cooling rate, but such changes in MC carbide cannot be found when the cooling rate is high.

关键词：氧碳化物氮含量物理性能碳化物

Effects of dealloying and heat treatment parameters on microstructures of nanoporous Pd

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Journal of Materials Science & Technology 2020年第13期47卷 123-129页

作者： Y.z.Chen x.Y.Ma W.x.zhang h.Dong G.b.Shan Y.b.Cong C.li C.l.Yang F.liu State Key lab.of Solidification Processing Northwestern Polytechnical University710072 Xi’anChina

Microstructures of nanoporous Pd are essentially important for its physical and chemical *** this work,we show that the microstructures of nanoporous Pd can be tuned by adjusting compositions of the precursor alloys,and dealloying and heat treatment *** the ligament and pore sizes decrease with increasing the electrochemical potential upon dealloying and the concentration of noble component in the precursor *** treatment causes coarsening of the nanoporous *** a critical temperature,the nanoporous structures are subjected to significant *** the critical temperature,surface diffusion is believed to dominate the coarsening *** the critical temperature,the nanoporous structure coarsens remarkably at a rather high rate,which is ascribed to a multiple-mechanism controlled process.

关键词： Nanoporous metals Microstructure Dealloying Kinetics Coarsening

Simulations of deformation and damage processes of SiCp/Al composites during tension

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Journal of Materials Science & Technology 2018年第4期34卷 627-634页

作者： J.F.zhang x.x.zhang Q.z.wang b.l.xiao z.Y.Ma Shenyang National laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China university of Chinese Academy of Sciences Beijing 100049China

The deformation, damage and failure behaviors of 17 vol.% SiCp/2009AI composite were studied by micro- scopic finite element （FE） models based on a representative volume element （RVE） and a unit cell. The RVE having a 3D realistic microstructure was constructed via computational modeling technique, in which an interface phase with an average thickness of 50 nm was generated for assessing the effects of interracial properties. Modeling results showed that the RVE based FE model was more accurate than the unit cell based one. based on the RVE, the predicted stress-strain curve and the fracture morphology agreed well with the experimental results. Furthermore, lower interface strength resulted in lower flow stress and ductile damage of interface phase, thereby leading to decreased elongation. It was revealed that the stress concentration factor of SiC was -2.0： the average stress in SiC particles reached -1200 MPa, while that of the composite reached -600 MPa.

关键词： Metal matrix composites (MMCs) Fracture Finite element (FE) analysis Interfacial strength Tensile strength Representative volume element (RVE)

Rotational and translational domains of beta precipitate in aged binary Mg-Ce alloys

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Journal of Magnesium and Alloys 2021年第3期9卷 1039-1056页

作者： b.z.Sun h.x.zhang Y.Dong J.x.Ren Y.Tian G.M.xie J.Tan Y.h.Sun Na xiao School of Materials Science and Engineering Northeastern UniversityShenyang 110819China State Key lab Rolling&Automat Northeastern UniversityShenyang 110819China Key laboratory for Anisotropy and Texture of Materials Ministry of EducationNortheastern UniversityShenyang 110819China Analytical and Testing Center Northeastern UniversityShenyang 110819China

The structural evolution fromβ_(1)(Mg_(3)Ce)toβ(Mg_(12)Ce)precipitates,which takes place at the over-aged stage of binary Mg-Ce alloys,are investigated by high-angle annular dark-field scanning transmission electron *** structural transformation mainly occurs in theh_(β1)crystallographic planes,where the newly formedβlattices exhibit two categories of domain structures,namely rotational and translational *** rotational domain is composed of threeβdomains(β_(RA),β_(Rb)andβ_(RC)),which are related by a 120°rotation with respect to each other around the 111_(β1)axis of theirβ_(1)parent ***h_(β1)crystallographic planes can provide four sets of sublattices with the same orientation for an initial nucleation ofβ*** leads to the formation of four translationalβdomains(β_(TA),β_(Tb),β_(TC)andβ_(TD)),among which any two differ by a vector of 1/6112_(β1).We deduce theoretically that there exist twenty-fourβdomains during this ***,considering the interfacial misfit,only one-third of domains can grow up and eventually formsβ***,a majority ofβribbons overlap partiallyβ_(1)plate,which is beneficial to relax interfacial strain amongβ,β_(1)andα-Mg matrix(α/β/β_(1)).The configuration of multipleβdomains can effectively regulate interfacial misfit ofα/βandβ/β_(1),which are responsible for enhancing the hardness and strength of Mg-Ce ***,this study aims to provide some clues to improve the over-aged performance of magnesium alloys by constructingβdomains and optimizing theα/β/β_(1)interface.

关键词： Magnesium alloys hAADF-STEM Rotational domain Translational domain Phase transition Interfacial misfit