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Effect of trace HA on microstructure, mechanical properties and corrosion behavior of Mg-2Zn-0.5Sr alloy

Journal of Materials Science & Technology 2018年第2期34卷 299-310页

作者： Jian-Xing li yuan Zhang jing-yuan li Jian-Xin Xie School of Materials Science and Engineering University of Science and Technology Beijing Institute for Advanced Materials and Technology University of Science and Technology Beijing

Effect of the addition of trace HA particles into Mg-2Zn-0.5Sr on microstructure, mechanical properties, and bio-corrosion behavior was investigated in comparison with pure Mg. Microstructures of the Mg-2Zn-0.5Sr-xHA composites （x= 0, 0.1 and 0.3 wt%） were characterized by optical microscopy （OM）, scanning electron microscopy （SEM） equipped with energy dispersion spectroscopy （EDS） and X-ray diffraction （XRD）. Results of tensile tests at room temperature show that yield strength （YS） of Mg- 2Zn-0.5Sr/HA composites increases significantly, but the ultimate tensile strength （UTS） and elongation decrease with the addition of HA particles from 0 up to 0.3 wt%. Bio-corrosion behavior was investigated by immersion tests and electrochemical tests. Electrochemical tests show that corrosion potential （Ecorr） of Mg-2Zn-0.5Sr/HA composites significantly shifts toward nobler direction from -1724 to -1660 mVscE and the corrosion current density decreases from 479.8 to 280.8 ***^-2 with the addition of HA particles. Immersion tests show that average corrosion rate of ***/HA composites decreases from 11.7 to 9.1 mm/year with the addition of HA particles from 0 wt% up to 0.3 wt%. Both microstructure and mechanical properties can be attributed to grain refinement and mechanical bonding of HA particles with second phases and α-Mg matrix. Bio-corrosion behavior can be attributed to grain refinement and the formation of a stable and dense CaHPO4 protective film due to the adsorption of Ca^2＋ on HA particles. Our analysis shows that the Mg-2Zn-0.5Sr/0.3HA with good strength and corrosion resistance can be a good material candidate for biomedical applications.

关键词： Magnesium alloys Bio-composites Hydroxyapatite Microstructure Mechanical property Bio-corrosion behavior

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Effect of dislocation structure evolution on low-angle grain boundary formation in 7050 aluminum alloy during aging

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International Journal of Minerals,Metallurgy and Materials 2015年第7期22卷 721-728页

作者： Wei Gu jing-yuan li Yi-de Wang School of Materials Science and Engineering University of Science and Technology Beijing

The effect of dislocation structure evolution on low-angle grain boundary formation in 7050 aluminum alloy during aging was studied by using optical microscopy, transmission electron microscopy, and electron backscatter diffraction analysis of misorientation angle distribution, cumulative misorientation and geometrically necessary dislocation （GND） density. Experimental results indicate that coarse spindle-shaped grains with the dimension of 200 μm- 80 μm separate into fine equiaxed grains of 20μm in size as a result of newborn low-angle grain boundaries formed during the aging process. More specifically, the dislocation arrays, which are rearranged and formed due to scattered dislocations during earlier quenching, transform into low-angle grain boundaries with aging time. The relative frequency of 3°-5° low-angle grain boundaries increases to over 30%. The GND density, which describes low-angle grain boundaries with the misorientation angle under 3°, tends to decrease during initial aging. The inhomogeneous distribution of GNDs is affected by grain orientation. A decrease in GND density mainly occurs from 1.83 × 10^13 to 4.40 × 10^11 m^-2 in grains with 〈111〉 fiber texture. This is consistent with a decrease of unit cumulative misorientation. Precipitation on grain boundaries and the formation of a precipitation free zone （PFZ） are facilitated due to the eroding activity of the Graft etchant. Consequently, low-angle grain boundaries could be readily viewed by optical microscopy due to an increase in their electric potential difference.

关键词： aluminum alloys low-angle grain boundaries dislocation structure aging dislocation density

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Effects of asymmetric rolling process on ridging resistance of ultra-purified 17%Cr ferritic stainless steel

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International Journal of Minerals,Metallurgy and Materials 2018年第2期25卷 216-225页

作者： Cheng-zhuang Lu jing-yuan li Zhi Fang School of Materials Science and Engineering University of Science and Technology Beijing Institute for Advanced Materials and Technology University of Science and Technology Beijing

In ferritic stainless steels, a significant non-uniform recrystallization orientation and a substantial texture gradient usually occur, which can degrade the ridging resistance of the final sheets. To improve the homogeneity of the recrystallization orientation and reduce the texture gradient in ultra-purified 17%Cr ferritic stainless steel, in this work, we performed conventional and asymmetric rolling processes and conducted macro and micro-texture analyses to investigate texture evolution under different cold-rolling conditions. In the conventional rolling specimens, we observed that the deformation was not uniform in the thickness direction, whereas there was homogeneous shear deformation in the asymmetric rolling specimens as well as the formation of uniform recrystallized grains and random orientation grains in the final annealing sheets. As such, the ridging resistance of the final sheets was significantly improved by employing the asymmetric rolling process. This result indicates with certainty that the texture gradient and orientation inhomogeneity can be attributed to non-uniform deformation, whereas the uniform orientation gradient in the thickness direction is explained by the increased number of shear bands obtained in the asymmetric rolling process.

关键词： ferritic stainless steel asymmetric rolling surface ridging texture shear bands

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Mechanism of hot-rolling crack formation in lean duplex stainless steel 2101

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International Journal of Minerals,Metallurgy and Materials 2016年第4期23卷 425-433页

作者： Zhi-hui Feng jing-yuan li Yi-de Wang School of Materials Science and Engineering University of Science and Technology Beijing

The thermoplasticity of duplex stainless steel 2205（DSS2205） is better than that of lean duplex steel 2101（LDX2101）, which undergoes severe cracking during hot rolling. The microstructure, microhardness, phase ratio, and recrystallization dependence of the deformation compatibility of LDX2101 and DSS2205 were investigated using optical microscopy（OM）, electron backscatter diffraction（EBSD）, Thermo-Calc software, and transmission electron microscopy（TEM）. The results showed that the phase-ratio transformations of LDX2101 and DSS2205 were almost equal under the condition of increasing solution temperature. Thus, the phase transformation was not the main cause for the hot plasticity difference of these two steels. The grain size of LDX2101 was substantially greater than that of DSS2205, and the microhardness difference of LDX2101 was larger than that of DSS2205. This difference hinders the transfer of strain from ferrite to austenite. In the rolling process, the ferrite grains of LDX2101 underwent continuous softening and were substantially refined. However, although little recrystallization occurred at the boundaries of austenite, serious deformation accumulated in the interior of austenite, leading to a substantial increase in hardness. The main cause of crack formation is the microhardness difference between ferrite and austenite.

关键词： duplex stainless steel hot rolling crack formation thermoplasticity grain size precipitates softening mechanisms

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Wave effects on the anti-liquefaction of the seabed around composite bucket foundation of offshore wind turbines

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Journal of Hydrodynamics 2021年第6期33卷 1291-1302页

作者： li-hua Wang Jin-feng Zhang Run-bo Cai jing-yuan li State Key Laboratory of Hydraulic Engineering Simulation and Safety Tianjin University Tianjin 300072China Key Laboratory of Earthquake Engineering Simulation and Seismic Resilience of China Earthquake Administration Tianjin UniversityTianjin 300350China

By using the open-source software OpenFOAM and the grid generation tool the integrated computer engineering and manufacturing code for computational fluid dynamics(ICEM CFD),a computational fluid dynamics-computational structural dynamics(CFD-CSD)coupling model is *** dynamic response and the liquefaction of the seabed around the composite bucket foundation of the offshore wind turbines in the Xiangshui area of Jiangsu Province are *** pore water pressure,the effective stress,the liquefaction depth and the anti-liquefaction effect of the overlying stones are *** is shown that the seabed around the composite bucket foundation will be liquefied under 50 year return waves,the liquefaction width is approximately 1/3 of the wavelength,and the maximum liquefaction depth is approximately 1/4 of the wave *** addition,the overlying stones provide an effective anti-liquefaction ***,less porous overlying stones have a better anti-liquefaction effect.

关键词： Offshore wind turbine composite bucket foundation wave anti-liquefaction overlying stones

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A New Route for Synthesis of Entecavir

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Chinese Chemical Letters 2006年第7期17卷 907-910页

作者： li Wei GUO yuan jing XIAO li Ping YANG Department of chemistry East China Normal University Shanghai 200062

A new economical synthetic route of the key intermediate 6. The synthesis of a modified Mitsunobu reaction. of entecavir was presented, involving the preparation 6 was conveniendy achieved in good overall yield by a m... 详细信息

关键词： Entecavir new route synthesis.

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镍钨基硫化态和氮化态催化剂对十氢萘选择性开环性能研究

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现代化工 2024年第7期44卷 151-155页

作者：袁利静马纪伟崔昇张莉王潇潇孟现洁太原科技大学能源与材料工程学院山西太原030024 中国科学院山西煤炭化学研究所应用催化与绿色化工实验室山西太原030000 太原理工大学化学工程与技术学院山西太原030024

通过不同预处理方式制备镍钨硫化态和氮化态催化剂,利用X射线衍射、吡啶红外光谱、元素分析、CO滴定等技术对催化剂进行表征。以十氢萘为探针分子,利用固定床反应器考察不同预处理方式及负载量对催化剂十氢萘选择性开环反应转化率和寿... 详细信息

通过不同预处理方式制备镍钨硫化态和氮化态催化剂,利用X射线衍射、吡啶红外光谱、元素分析、CO滴定等技术对催化剂进行表征。以十氢萘为探针分子,利用固定床反应器考察不同预处理方式及负载量对催化剂十氢萘选择性开环反应转化率和寿命的影响规律。结果表明,氮化态催化剂初始转化率及选择性开环活性高,这与氮化态催化剂金属位活性高有关,但其稳定性低于硫化态催化剂,这是由于十氢萘在金属位脱氢后未能及时转移至酸性位开环,使其发生过度脱氢导致结焦失活。

关键词：镍钨催化剂硫化态氮化态十氢萘选择性开环

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Effects of heat treatment on the microstructures and mechanical properties of a new type of nitrogen-containing die steel

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International Journal of Minerals,Metallurgy and Materials 2012年第6期19卷 511-517页

作者： jing-yuan li Peng Zhao Jun Yanagimoto Sumio Sugiyama Yu-lai Chen School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China Institute of Radar and Avionics Aviation Industry Corporation of China Suzhou 215151 China Institute of Industrial Science the University of Tokyo Tokyo 153-8505 Japan Engineering Research Institute University of Science and Technology Beijing Beijing 100083 China

Nitrogen can increase the strength of steels without weakening the toughness and improve the corrosion resistance at the same time. Compared with conventional nitrogen-free die steels, a new type of nitrogen-containing die steel was developed with many superior properties, such as high strength, high hardness, and good toughness. This paper focused on the effects of heat treatment on the microstruc- tures and mechanical properties of the new type of nitrogen-containing die steel, which were investigated by the optimized deformation process and heat treatment. Isothermal spheroidal annealing and high-temperature quenching as well as high-temperature tempering were ap- plied in the experiment by means of an orthogonal method after the steel was multiply forged. The mechanical properties of nitro- gen-containing die steel forgings are better than the standard of NADCA #207-2003.

关键词： die steels nitrogen heat treatment microstructure mechanical properties forgings

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FEM analysis of metal flowing behaviors in porthole die extrusion based on the mesh reconstruction technology of the welding process

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International Journal of Minerals,Metallurgy and Materials 2010年第6期17卷 763-769页

作者： Dong-nan Huang Zhi-hao Zhang jing-yuan li Jian-xin Xie Advanced Materials and Technologies Institute University of Science and Technology Beijing Beijing 100083 China School of Materials Science and Engineering Inner Mongolia University of Technology Huhhot 010051 China

A reconstruction technology of finite element meshes based on reversal engineering was applied to solve mesh penetration and separation in the finite element simulation for the divergent extrusion. The 3D numerical simulation of the divergent extrusion process in- cluding the welding stage for complicated hollow sections was conducted. Based on the analysis of flowing behaviors, the flowing velocities of the alloy in portholes and near the welding planes were properly controlled through optimizing the expansion angle as well as porthole ar- eas and positions. After the die structure optimization, defects such as warp, wrist, and the wavelike are eliminated, which improves the sec- tion-forming quality. Meanwhile, the temperature distribution in the cross section is uniform. Especially, the temperature of the C-shape notch with a larger thickness is lower than that of other regions in the cross section, which is beneficial for balancing the alloy flowing velocity.

关键词： numerical simulation extrusion metal forming metal flow reconstruction

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Enhanced Strength and Corrosion Resistance of Mg–2Zn–0.6Zr Alloy with Extrusion

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Acta Metallurgica Sinica(English Letters) 2019年第1期32卷 10-22页

作者： Luan-Xiang Wang Ren-Bo Song Chang-Hong Cai jing-yuan li School of Materials Science and Engineering University of Science and Technology Beijing

The microstructure, mechanical properties and corrosion behavior of Mg–2 Zn–0.6 Zr alloy under the as-cast and asextruded conditions were investigated. Microstructure analysis indicated the remarkable grain refinement by extrusion, as well as notable reductions in volume fraction and size of precipitate phases. As compared with the as-cast alloy, the asextruded alloy exhibited better mechanical performance, especially in yield strength which was promoted from 51 to 194 MPa. Refined grains, dispersive precipitate phases and texture were thought to be the main factors affecting the improved performance in strength. The electrochemical measurement and immersion test revealed the corrosion rate of Mg–2 Zn–0.6 Zr alloy by extrusion decreased from 1.68 to 0.32 mm/year. The reasons for the enhanced corrosion resistance were mainly attributed to the decreased volume fraction and Volta potential of the precipitate phases, the refinement of the grain size, as well as the formation of more protective corrosion film.

关键词： Mg–2Zn–0.6Zr Extrusion Strength Corrosion behavior

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