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PHOsPHORUs GRAIN BOUNdARY sEGREGATION IN A P-dOPEd 2.25Cr1Mo sTEEl

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Acta Metallurgica sinica(English letters) 2004年第5期17卷 639-644页

作者： d.d.shen Z.X.Yuan J.liu s.H.song l.Q.Wen TheHubeiProvinceKeylaboratoryofCeramicsandRefractories WuhanUniversityofScienceandTechnologyWuhan430081China schoolofMaterialsscienceandEngineering NanjingUniversityofAeronauticsandAstronauticsNanjing210016China

Grain boundary segregation of phosphorus during tempering at 540℃ after quenching from 980℃ is examined for a P-doped 2.25Cr1Mo steel by means of Auger electron spectroscopy. The solute-boundary binding energy and the diffusion coefficient for phosphorus are determined by virtue of the measured segregation kinetics along with the equilibrium segregation theory. The obtained values of the above parameters are discussed with comparison to those found in the literature for low-alloy steels.

关键词： segregation grain boundary low-alloy steel phosphorus

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

A cellular automata model for simulating grain structures with straight and hyperbolic interfaces

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International Journal of Minerals,Metallurgy and Materials 2012年第8期19卷 699-710页

作者： A.Ramírez-lópez M.Palomar-Pardavé d.Muñoz-Negrón C.duran-Valencia s.lópez-Ramirez G.soto-Cortés Materials and Energy department Metropolitan Autonomous UniversityMexico department of Industrial Engineering Technological Autonomous Institute of MexicoMexico department of Molecular Engineering Mexican Institute of PetroleumMexico

A description of a mathematical algorithm for simulating grain structures with straight and hyperbolic interfaces is shown. The presence of straight and hyperbolic interfaces in many grain structures of metallic materials is due to different solidification conditions, in- eluding different solidification speeds, growth directions, and delaying on the nucleation times of each nucleated node. Grain growth is a complex problem to be simulated; therefore, computational methods based on the chaos theory have been developed for this purpose. straight and hyperbolic interfaces are between columnar and equiaxed grain structures or in transition zones. The algorithm developed in this work involves random distributions of temperature to assign preferential probabilities to each node of the simulated sample for nucleation according to previously defined boundary conditions. Moreover, more than one single nucleation process can be established in order to gen- erate hyperbolic interfaces between the grains. The appearance of new nucleated nodes is declared in sequences with a particular number of nucleated nodes and a number of steps for execution. This input information influences directly on the final grain structure （grain size and dislribution）. Preferential growth directions are also established to obtain equiaxed and columnar grains. The simulation is done using rou- tines for nucleation and growth nested inside the main function. Here, random numbers are generated to place the coordinates of each new nucleated node at each nucleation sequence according to a solidification probability. Nucleation and growth routines are executed as a func- tion of nodal availability in order to know if a node will be part of a grain. Finally, this information is saved in a two-dimensional computa- tional array and displayed on the computer screen placing color pixels on the corresponding position forming an image as is done in cellular automaton.

关键词： grain growth interfaces grain size and shape computational methods algorithms cellular automata computer simulation

Effect of samarium doping on structural, optical and magnetic properties of vertically aligned ZnO nanorod arrays

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Journal of Rare Earths 2017年第10期35卷 1002-1007页

作者： d.Ranjith Kumar K.s.Ranjith l.R.Nivedita R.T.Rajendra Kumar department of Nanoscience and Technology Bharathiar University Coimbatore India Advanced Materials and devices laboratory (AMdl) Department of Physics Bharathiar University Coimbatore India

samarium doped vertically aligned one dimensional ZnO nanorod（NR） arrays were grown by vapor phase transport（VPT） method through vapor solid（Vs） growth process. Influence of different concentrations（0% to 8%） of sm（all sm contents in the paper are in mass fraction） on the ZnO NR arrays were investigated by X-ray diffraction（XRd）, field emission scanning electron microscopy（FEsEM）, photoluminescence（Pl）, Raman spectroscopy and vibrating sample magnetometry（VsM） techniques, respectively. X-ray diffraction studies revealed that the ZnO NR arrays were perfectly oriented along（002） crystallographic orientation with wurtzite crystal structure. Photoluminescence results showed an increase in oxygen vacancies due to increase in sm doping. M-H curves revealed enhanced ferromagnetic behavior, and the magnetic moment values were 0.45, 0.363, 1.694, 3.613 and 2.197 emu/cm^3 for（0–8%） sm doped ZnO NR arrays respectively. The curve revealed that paramagnetic behavior was observed for undoped ZnO NR arrays and on increasing the sm dopant to 4%, paramagnetic switched to ferromagnetic behavior.

关键词： sm doped ZnO room temperature ferromagnetism(RTFM) defects rare earths

THE ACCURATE MOlECUlAR FORMUlA OF "Ti_(11)Ni_(14)"　PHAsE

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Acta Metallurgica sinica(English letters) 1998年第1期11卷 56-60页

作者： C.l.Chu G.J.shen s.d.Wang B.li s.G.Zhang Z.d.Yin Harbin Inst of Technology Harbin China

From the orientation relationship between 'Ti11Ni14' phase and matrix phase (B2),the accurate molecular formula of 'Ti11N14' phase has been derived in this paper. The results also show that the rhombohedral unit cell ... 详细信息

关键词： TiNi shape memory alloy self-propagating high-temperature synthesis (sHs)

IMPROVING THE sURFACE PROPERTY OF TC4 AllOY BY lAsER NITRIdING ANd ITs MECHANIsM

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Acta Metallurgica sinica(English letters) 2006年第2期19卷 151-156页

作者： Y.l. Yang G.J. Zhao d. Zhang C.s. liu Gollege of sdence Northeastern University Shenyang 110004 Ghina College of Material and Metallurgy Northeastern University Shenya g 110004 China

The mixing technology of laser and heated nitrogen was applied to improve the surface hardness of titanium alloy （ TC4 ）. The samples were nitrided with laser power density of 6.s × 10^6sW. cm^-2, the scanning speed varioas from 100 to 500mm ·min^-1. The nitrogen gas was pre-heated to 300℃ to accelerate the nitriding process. some interested samples were tested with XRd method （X-ray diffraction） to analyze the composition of nitrides, and the surface hardness of HV was measured. The results show that TiN and Ti2N were formed on the surface of Ti alloy with proper nitriding parameters, but TiN is the main composition. The surface hardness increased by three times, which is from the original value of 269to 794kg·mm^-2. The mechanism of the mixing technology is considered mainly of the activation of nitrogen by laser power and the pre-heated process which accelerated the nitriding process. The nitridation process can be considered as six steps given in detail. The result by analyzing the mechanism of improving the surface property of TiAl alloy shows the improvement of surface property due to two factors： the first reason is the result of laser annealing, and the second one is the formation of TiN.

关键词： laser nitridation surface property Ti alloy

sTUdY ON REdUCING THE CORE lOss OF GRAIN ORIENTEd sIlICON sTEEl ANd IMPROVING ITs AGING PROPERTY BY lAsER NITRIdING TECHNIQUE IN ATMOsPHERIC AMBIENT

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Acta Metallurgica sinica(English letters) 2005年第4期18卷 533-538页

作者： Y.l. Yang C.s. liu F.J. sun d. Zhang College of science Northeastern University Shenyang 110004 China College of Material ＆ Metallurgy Northeastern University Shenyang 110004China

CW-CO2 laser nitriding technique was applied to improve the properties （such as aging property and the core loss） of grain oriented silicon steel. The samples were nitrided with regular space. laser power density and scanning speed were chosen as 7.8×10^5W·cm^-2 and 100mm·min^-1. By some laser irradiation, Fe4N and Fe3N were formed in the nitrided zone. The nitrided samples were annealed at the temperatures ranged from 100 to 90℃. The core loss of some interested samples was tested. The results show that the core loss of the nitrided samples with different thickness of 0.23 and 0.30mm decreased by 14.9% and 9.4% respectively, and the aging property were improved up to 800℃. The mechanism of laser nitriding to improve the properties of grain oriented silicon steel is discussed.

关键词： laser nitriding grain oriented silicon steel sheet core loss aging property

Critical transitions in the shape morphing of kirigami metallic glass

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Journal of Materials science & Technology 2021年第2期61卷 204-212页

作者： d.X.Han l.Zhao s.H.Chen G.Wang K.C.Chan Advanced Manufacturing Technology Research Center Department of Industrial and Systems EngineeringThe Hong Kong Polytechnic UniversityHung HornKowloonHong KongChina school of Mechanical Engineering Hefei University of TechnologyHefei230009China laboratory for Microstructures Institute of MaterialsShanghai UniversityShanghai200444China

Kirigami, the ancient Japanese paper cutting technique, has been applied to achieve high stretchability and low energy loss of designed metallic glass. despite the exploration of the underlying deformation mechanism of kirigami-inspired structures from the energy point of view, the morphable responses of the kirigami patterns and the origin of the kirigami response are yet to be fully understood. This study reveals the mechanical driven-forms of the kirigami structure with the corresponding deformation stages. Based on the beam deflection theory, the elastic buckling behavior of kirigami metallic glass is manifested and a critical force prediction model is developed. Moreover, a force concentration parameter is introduced in the rigid-plastic deformation stage, predicting the nominal ultimate force. The kirigami-inspired facture force is firstly proposed. The findings of these models are in good agreement with the experimental sizedependent kirigami responses, and expected to provide significant insights into the understanding of the deformation behavior and the design of kirigami metallic glasses.

关键词： Metamaterial Kirigami metallic glass Critical load size effect Beam deflection

青藏高原及其周边新近纪综合地层、生物群与古地理演化

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中国科学：地球科学 2024年第4期54卷 1343-1378页

作者：邓涛方小敏李强王世骐吴飞翔侯素宽马姣江左其杲孙丹辉郑妍史勤勤孙博阳李录中国科学院古脊椎动物与古人类研究所中国科学院脊椎动物演化与人类起源重点实验室北京100044 中国科学院生物演化与环境卓越创新中心北京100044 中国科学院大学地球与行星科学学院北京100049 中国科学院青藏高原研究所中国科学院青藏高原地球科学卓越创新中心北京100101 北京大学地球与空间科学学院造山带与地壳演化教育部重点实验室北京100871

青藏高原在新近纪的显著隆升对东亚乃至全球的气候环境产生了巨大的影响,因此,建立青藏高原新近纪地层框架对地球科学各领域的研究都有重要的意义.国际新近纪年代地层系统以海相为标准,分为中新统的6个阶和上新统的2个阶.新生代以来,陆... 详细信息

青藏高原在新近纪的显著隆升对东亚乃至全球的气候环境产生了巨大的影响,因此,建立青藏高原新近纪地层框架对地球科学各领域的研究都有重要的意义.国际新近纪年代地层系统以海相为标准,分为中新统的6个阶和上新统的2个阶.新生代以来,陆相地层在陆地上所占的比例迅速增加,到新近纪时已远远超过海相地层,在青藏高原及其周边地区几乎全部为陆相地层.中国的中新统包括5个阶,上新统包括2个阶,除中中新统的通古尔阶以15Ma为底界外,其余各阶都与对应的国际海相阶具有相同的古地磁定义和时限.哺乳动物化石在新生代陆相地层的划分对比中占有非常重要的地位,在新近系尤其倚重于啮齿类、食肉类、长鼻类、奇蹄类和偶蹄类化石.青藏高原有不少地层出露好且富含哺乳动物化石的盆地,新近系谢家阶和灞河阶的底界层型剖面分别位于西宁盆地和临夏盆地,并有精细的古地磁定年与哺乳动物化石相互配合,其余各阶的底界在青藏高原也可以有效确定.东亚地区许多哺乳动物首现属出现在青藏高原及其周边地区,在东北缘的临夏盆地和西南缘的西瓦立克地区尤为典型,其中,西瓦立克的原恐象Prodeinotherium首现于中新统底界,旧大陆最早的三趾马Hipparion首现于临夏盆地的灞河阶底界.对青藏高原及其周缘地区新生代沉积物及其所含的哺乳动物化石进行的牙釉质和古土壤碳氧同位素分析重建了气候环境背景及植被发育特征,发现其既与全球变化相关,又有地区性的特点.根据碳同位素变化得到的晚中新世C4植物扩张事件证据来自于青藏高原南缘,但形成鲜明对比的是,多个食草哺乳动物类群和古土壤碳酸盐及有机质的δ13C指示在青藏高原北缘直到新近纪末期仍然缺少明确或显著的C4植物信号.δ^(18)O分析显示在新生代存在几次重大的气候变化事件,尤其是晚中新世末期约7Ma的δ^(18)O正漂指示了青藏高原南北两侧向更干旱环境的转变.青藏高原在晚中新世的强烈隆升强化了海陆热力对比,由此加强了季风环流并导致C4植被在南亚扩张,但能够为中国北方带来大气降水和C4植物适宜气候的东亚夏季风还不足以影响到青藏高原北部地区.青藏高原在中新世整体上已上升至海拔3000m左右,成为阻碍大型哺乳动物交流的屏障;至上新世达到4000m以上的现代海拔高度,由此形成冰冻圈环境,导致冰期动物群祖先类型出现.

关键词：青藏高原新近系陆相地层哺乳动物化石古地磁