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Catalytic nucleation of a meta-stable δ phase in phase-seeded undercooled Fe75Ni25 melts

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Progress in Natural Science:Materials International 2012年第3期22卷 258-262页

作者： y.z. Chen, X.H. shi, F. Liu, G.C. yang, y.H. zhou State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an, Shaanxi 710072, China State Key Laboratory of Solidification Processing Northwestern Polytechnical University Xi’an Shaanxi 710072 China

Undercooled Fe75Ni25 melts were phase-seeded by a high purity iron. It was found that above a critical undercooling, △Tc 135 K, a metastable δ phase (b.c.c) solidifies from the iron-seeded melts instead of a thermodynamically stable γ phase (f.c.c). While undercooling of the melt (△T) is below △Tc, solidification of the γ phase prevails in the iron-seeded melts. For the undercooled melts subjected to spontaneous nucleation, the γ phase always solidifies. After solidification, the as-solidified γ phase transforms completely to martensite; whereas the as-solidified metastable δ phase partially transforms to the γ phase, and then to martensite. The untransformed δ phase retains as a-ferrite particles in the microstructures. Based on the classical nucleation theory, catalytic nucleation of the metastable δ phase in the phase-seeded undercooled Fe75Ni25 melts was analyzed. It was quantitatively demonstrated that when △T>△Tc, the formation of the δ phase can be ascribed to a better catalytic effect of the iron on its nucleation than that on the nucleation of the γ phase.

关键词： Iron-nickel alloy Rapid solidification Microstructure Nucleation Undercooling

A pathway to improve low-cycle fatigue life of face-centered cubic metals via grain boundary engineering

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Journal of Materials Science & Technology 2022年第18期113卷 82-89页

作者： X.J.Guan z.P.Jia S.M.Liang F.shi X.W.Li Department of Materials Physics and Chemistry School of Materials Science and EngineeringNortheastern UniversityShenyang 110819China State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang 110819China Key Laboratory for Anisotropy and Texture of Materials Ministry of EducationNortheastern UniversityShenyang 110819China

To probe a pathway to improve the low-cycle fatigue life of face-centered cubic(FCC)metals via grain boundary engineering(GBE),the tension-tension fatigue tests were carried out on the non-GBE and GBE Cu-16 at.%Al alloys at relatively high stress *** results indicate that the cyclic strain localiza-tion and cracking at grain boundaries(GBs)can be effectively suppressed,especially at increased stress amplitude,by an appropriate GBE treatment that can result in a higher resistance to GB cracking and a greater capability of compatible ***,the sensitivity of fatigue life to stress amplitude can be weakened by GBE,and the low-cycle fatigue life of Cu-16 at.%Al alloys is thus distinctly improved.

关键词： Cu-Al alloy Grain boundary engineering Fatigue life Crack nucleation Stress amplitude

A fast numerical method of introducing the strengthening effect of residual stress and strain to tensile behavior of metal matrix composites

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Journal of Materials Science & Technology 2021年第28期87卷 167-175页

作者： J.F.zhang X.X.zhang H.Andrä Q.z.Wang B.L.Xiao z.y.Ma shi-changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China University of Chinese Academy of Sciences Beijing 100049China Fraunhofer Institute for Industrial Mathematics Fraunhofer-Platz 1Kaiserslautern 67663Germany

Thermal residual stress and strain(TRSS)in particle reinforced metal matrix composites(PRMMCs)are believed to cause strengthening effects,according to previous ***,the representative volume element(RVE)based computational homogenization technique was used to study the tensile deformation of PRMMCs with different particle aspect ratios(AR).The influence of TRSS was assessed quantitatively via comparing simulations with or without the cooling *** was found that the strengthening effect of TRSS was affected by the particle *** the average strengthening effect of TRSS,a fast method of introducing the strengthening effect of TRSS to the tensile behavior of PRMMCs was *** new method has reduced the computational cost by a factor *** effect of TRSS on continuous fiber-reinforced metal matrix composite was found to have a softening-effect during the entire tensile deformation process because of the pre-yield effect caused by the cooling process.

关键词： Metal matrix composites(MMC) Finite element analysis(FEA) Representative volume element(RVE) Residual stress and strain Aspect ratio

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SnO高压结构稳定性和电学性能研究

光谱学与光谱分析 2025年第1期45卷 82-87页

作者：刘涛黄宇轩高金金王世霞上海理工大学材料与化学学院上海200093

近年来氧化亚锡(SnO)在光、电等方面的应用日益广泛,为了拓宽SnO的应用范围,采用拉曼光谱原位测试和第一性原理计算对高压条件下SnO的结构性能和电子性质进行研究。SnO表征结果:扫描电子显微镜结果显示,所选取SnO样品为具有横向尺寸的... 详细信息

近年来氧化亚锡(SnO)在光、电等方面的应用日益广泛,为了拓宽SnO的应用范围,采用拉曼光谱原位测试和第一性原理计算对高压条件下SnO的结构性能和电子性质进行研究。SnO表征结果:扫描电子显微镜结果显示,所选取SnO样品为具有横向尺寸的片状堆叠,整体呈花状;X射线衍射图谱表明,SnO样品在常温常压下晶体结构为四方晶系结构(空间群P4/nmm)。采用Mao-Bell型金刚石压腔结合原位拉曼光谱探究了SnO样品在高压下的结构性能变化,结果显示:SnO在常压有四种拉曼振动模式(A_(1g)、B_(1g)、E_(1g)和E_(2g)),分别位于211、350、113和460 cm^(-1)波数附近,其中113和211 cm^(-1)为SnO拉曼特征峰。随SnO样品体系加压至12.5 GPa,压力使Sn分子间和原子间距不断减小,导致Sn-O键长缩短,当原子发生伸缩振动时,缩短的键长使得键能增大,因此活性拉曼振动模(E_(1g)和A_(1g))均向高频方向移动;随着体系压力的继续增大,晶格发生畸变进而使得非弹性散射强度降低,峰型宽化;当加压至8 GPa时,125和216 cm^(-1)附近振动模峰急剧减小;加压至10 GPa时两个特征峰完全消失,在非静水压环境下8~10 GPa时该物质发生了非晶化;当体系加压至12.5 GPa时,谱图中仍未出现新峰,表明高压下非晶化状态稳定。随后体系进行卸压,卸压至3 GPa后SnO的E_(1g)和A_(1g)模重新出现表明样品恢复低压下的晶体结构,卸至常压特征峰强度明显分别为110和209 cm^(-1)处与加压前吻合,证明了SnO高压相变行为具有可逆性。为进一步了解压力对SnO电学性能影响,使用第一性原理方法计算了SnO在常压和实验非晶化压力(8 GPa)下的电子性质,通过非晶化前后SnO的带隙宽度变化,探究压力对SnO导电性能的影响。结果显示,在常压下SnO为具有0.43 eV带隙的间接带隙半导体,在费米能级附近态密度没有发生重叠,8 GPa时SnO显示金属性质,由于SnO O-p、Sn-s和Sn-p轨道的态密度在费米能级处重叠,导致带隙的闭合,材料发生金属化。研究结果表明SnO高压下可能产生非晶化及压力所导致的非晶化行为可逆,同时高压导致SnO发生半导体到金属的转变,拓展了SnO高压结构和电学性质的探究,为SnO高压下的应用提供进一步帮助。

关键词： SnO 拉曼光谱金刚石压腔第一性原理电子性质

Mediating effect of self-efficacy in relationship between emotional intelligence and clinical communication competency of nurses

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International Journal of Nursing Sciences 2016年第2期3卷 162-168页

作者： B.zhu C.-R.Chen z.-y.shi H.-X.Liang B.Liu School of Nursing Henan UniversityKaifeng 475001China

Objective:This study investigates the emotional intelligence(EI),self-efficacy,and clinical communication ability of clinical nurses to explore the correlation among these three variables,and verify the mediating effect of self-efficacy on relationship between EI and communication ***:A total of 865 nurses were recruited and investigated using Wong and Law's Emotional Intelligence Scale,General Self-Efficacy Scale,and nurse clinical communication ***:The scores for EI and self-efficacy of nurses were 14.23±2.61 and 25.36±5.67,respectively,which were lower than the international norm(py of nurses was 4.14±*** clinical communication competency of nurses was positively correlated with EI and general ***,selfefficacy played an intermediary role between EI and clinical communication ***:Nursing administrators can improve the clinical communication ability of nurses by enhancing their self-efficacy and EI.

关键词： Clinical nurses Emotional intelligence Self-efficacy Clinical communication competency Mediating effect

Synchronous improvement of mechanical properties and stress corrosion resistance by stress-aging coupled with natural aging pre-treatment in an Al-zn-Mg alloy with high recrystallization fraction

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Journal of Materials Science & Technology 2022年第26期121卷 40-51页

作者： D.zhang H.C.Jiang z.J.Cui D.S.yan y.y.Song L.J.Rong CAS Key Laboratory of Nuclear Materials and Safety Assessment Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China shi-Changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Shandong Key Laboratory of Advanced Aluminum Materials and Technology Binzhou 256606China

Enhancing the strength of Al-zn-Mg alloys is critical to the weight-lightening of structural components in the application of high-speed trains and aerospace industries,while high stress corrosion cracking(SCC)susceptibility of Al-zn-Mg alloys(especially the alloy with high recrystallization fraction)with high strength makes it *** this study,the influence of tensile stress-aging coupled with natural aging pre-treatment on the mechanical properties and SCC resistance of Al-zn-Mg alloy with high recrystallization fraction has been *** results show that tensile stress-aging at 160℃can inhibit the dissolution of clusters/Guinier-Preston(GP)zones formed during long-term natural aging pre-treatment,which increases the number density of matrix precipitates(MPts),narrow the width of precipitate free zone(PFz),and dramatically improve the mechanical properties of the experimental Al-zn-Mg ***,the precipitation of the high density of MPts within the matrix will assume a large number of solute atoms during artificial aging,which will reduce the supplement of solute atoms to grain *** a result,the volume of anodic active grain boundary precipitates(GBPs)and the content of free solute atoms at grain boundaries are reduced,which reduces the possibility of initial nucleation and propagation of SCC *** coupled treatment method proposed in this study proves efficient in resolving the contradiction between the strength and SCC resistance in Al-zn-Mg alloy.

关键词： Al-zn-Mg alloy Natural aging Stress-aging Precipitates Stress corrosion cracking

An Epigenetic Role for Disrupted Paternal Gene Expression in Postzygotic Seed Abortion in Arabidopsis Interspecific Hybrids

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Molecular Plant 2015年第12期8卷 1766-1775页

作者： Ryan C. Kirkbride Helen Hong yu Gyoungju Nah Changqing zhang Xiaoli shi z. Jeffrey Chen Department of Molecular Biosciences Center for Computational Biology and Bioinformatics and Institute for Cellular and Molecular Biology The University of Texas at Austin Austin TX 78712 USA These authors contributed equally to this article. present address: Department of Plant Science Research Institute of Agriculture and Life Sciences Seoul National University Seou1151-921 South Korea present address: Plants for Human Health Institute North Carolina State University 600 Laureate Way Kannapolis NC 28081 USA present address: Institute of Theoretical Physics Chinese Academy of Sciences PO Box 2735 Beijing 100080 China

Interspecific hybrids often increase the levels of heterozygosity and hybrid vigor, but some interspecific hybrid seeds are aborted shortly after fertilization. The mechanism behind this postzygotic seed abortion is poorly understood. Here, we report genome-wide analysis of allelic expression changes in developing siliques and seeds in three F1 interspecific crosses between Arabidopsis thaliana （Col, Ler, or C24） and Arabidopsis arenosa. The majority of maternally expressed genes （MEGs） were shared among all three F1 interspecific crosses, whereas ~90% of 272 paternally expressed genes （PEGs） were found only in one or two F1 crosses, suggesting a role for disrupted paternal gene expression in seed abortion that varies in different crosses. Consistent with this notion, 12 PEGs in the infertile interspecific hybrids matched MEGs in fertile intraspecific hybrids. This disruption of PEGs in the interspecific hybrids was consistent with the upregulation of the genes in the paternal-excess interploidy cross （2X6） between a diploid mother and a hexaploid father, leading to the seed abortion. Moreover, a subset of PEGs in the interspecific crosses were also upregulated in the intraspecific hybrid metlXWT or meaXWT, in which the mutant of MET1 （DNA METHyL TRANSFERASE1） or MEDEA, a Polycomb Repressive Complex2 gene, was used as the maternal parent. These data suggest that maternal epigenetic factors and paternal gene expression play important roles in the postzygotic seed abortion in interspecific hybrids or neo-allopolyploids.

关键词： epigenetics imprinting paternal gene expression polyploidy hybrid incompatibility seeddevelopment

Triaxially deformed relativistic Hartree–Bogoliubov theory in Woods–Saxon basis

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Communications in Theoretical Physics 2023年第4期75卷 50-62页

作者：夏学伟施智 School of Physics and Electronic Engineering Center for Computational SciencesSichuan Normal UniversityChengdu 610068China United Imaging Healthcare Shanghai 201800China

A triaxially deformed relativistic Hartree–Bogoliubov theory in the Woods–Saxon basis is developed with the aim of treating the triaxial deformation,pairing correlations and continuum in a unified *** order to consider the triaxial deformation,the deformed potentials are expanded in terms of spherical harmonic functions in the coordinate *** order to take the pairing correlations into account and treat the continuum properly,by using the Dirac Woods–Saxon basis,which has correct asymptotic behavior,the relativistic Hartree–Bogoliubov equation with triaxial deformation is *** formalism of triaxially deformed relativistic Hartree–Bogoliubov theory in Woods–Saxon basis is *** an axially deformed nucleus24Ne and a triaxially deformed nucleus76Ge as examples,the numerical checks are performed.A weakly bound nucleus112Ge is taken as an example to carry out the necessary converge checks for the numerical *** addition,the ground-state properties of even–even germanium isotopes are *** evolutions of two-neutron separation energy,deformation,root-mean-square radii and density distribution with mass number are *** comparison between the calculations from the relativistic Hartree–Bogoliubov theory based on harmonic-oscillator basis and the triaxially deformed relativistic Hartree–Bogoliubov theory in Woods–Saxon basis is *** is found that the neutron drip line is extended from114Ge to118Ge in the triaxially deformed relativistic Hartree–Bogoliubov theory in Woods–Saxon basis.

关键词： covariant density functional theory deformed relativistic Hartree-Bogoliubov theory triaxial deformation continuum effect exotic nuclei

Fatigue Properties Improvement of Low-Carbon Alloy Axle Steel by Induction Hardening and Shot Peening:A Prospective Comparison

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Acta Metallurgica Sinica(English Letters) 2022年第8期35卷 1343-1356页

作者： G.C.Chu F.z.Hu X.J.jin y.zhang Q.Wang J.P.Hou z.F.zhang shi-Changxu Innovation Center for Advanced Material Institute of Metal ResearchChinese Academy of SciencesShenyang 110016.China School of Materials Science and Engineering University of Science and Technology of ChinaHefei 230026China Manshan Iron and Steel Co. Ltd.Maanshan 243000China School of Materials Science and Engineering Shanghai Jiao Tong UniversityShanghai 200240China Baowu Group Masteel Rail Transit Materials Technology Company Limited Maanshan 243000China

Fatigue fracture is the major threat to the railway axle, which can be avoided or delayed by surface strengthening. In this study, a low-carbon alloy axle steel with two states was treated by surface induction hardening and shot peening, respectively, to reveal the mechanism of fatigue property improvement by microstructure characterization, microhardness measurement, residual stress analysis, roughness measurement, and rotary bending fatigue tests. The results indicate that both quenching and tempering treatment can effectively improve the fatigue properties of the modified axle steel. In addition, induction hardening can create an ideal hardened layer on the sample surface by phase transformation from the microstructure of ferrite and pearlite to martensite. By comparison, shot peening can modify the microstructure in surface layer by surface severe plastic deformation introducing a large number of dislocation and even cause grain refinement. Both induction hardening and shot peening create compressive residual stress into the surface layer of axle steel sample, which can effectively reduce the stress level applied to the metal surface during the rotary bending fatigue tests. On the whole, the contribution of induction hardening to the fatigue life of axle steel sample is better than that of the shot peening, and induction hardening shows obvious advantages in improving the fatigue life of axle steel.

关键词： Surface strengthening Induction hardening Shot peening Axle steel Fatigue property improvement