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| 1 | Effect of Zr modification on solidification behavior and mechanical properties of Mg–Y–RE (WE54) alloy显示文摘Magnesium alloys containing rare earth elements (RE) have received considerable attention in recent years due to their high mechanical strength and good heat-resisting performance. Among them, Mg–5%Y–4%RE (WE54) magnesium alloy is a high strength sand casting magnesium alloy for use at temperatures up to 300 ℃, which is of great interest to engineers in the aerospace industry. In the present work, the solidification behavior of Zr-containing WE54 alloy and Zr-free alloy was investigated by computer-aided cooling curve analysis (CA-CCA) technique. And the solidification microstructure and mechanical properties of them were also investigated comparatively. It is found from the cooling curves and as-cast microstructure of WE54 alloy that the nucleation temperature of α-Mg in WE54 alloy increases after Zr addition, and the as-cast microstructure of the alloy is significantly refined by Zr. While the phase constitution of WE54 alloy is not changed after Zr addition. These phenomena indicate that Zr acts as heterogeneous nuclei during the solidification of WE54 alloy. Due to refined microstructure, the mechanical properties of Zr-containing WE54 alloy is much higher than Zr-free WE54 alloy. | Jilin Li Rongshi Chen Yuequn Ma Wei Ke | 2013 | Journal of Magnesium and Alloys2013，1，4： | 13 |
| 2 | Microstructure and mechanical properties of a high ductility Mg–Zn–Mn–Ce magnesium alloy显示文摘A high-ductility ZME200(Mg–2.3Zn–0.4Mn–0.2Ce^(1))alloy was newly developed for vehicle closure and structure applications,based on an earlier ZE20(Mg–2.0Zn–0.2Ce)alloy for extrusion applications.Previous study indicates that the hot deformation behavior of as-cast ZME200 alloy varies with processing parameters,namely temperature and strain rate.In this follow-up study,a conventional rolling process was optimized to obtain magnesium sheets with a very fine grain structure and high ductility.The microstructure,mechanical properties,and corrosion resistances of ZME200 alloy were investigated,and compared with those of commercial AZ31 magnesium alloy.It was demonstrated that the ZME200 alloy sheet exhibits extraordinarily higher ductility(36%in tensile elongation),much superior stretch formability(an Erichsen value of 9.5),lower anisotropy,comparable strength and corrosion resistance to AZ31 alloy.The unique RD–TD double split texture with remarkably reduced intensity and grain refinement gives rise to the significantly improved ductility and formability at room-temperature. | Lei Gao Hong Yan Jun Luo Alan A.Luo Rongshi Chen | 2013 | Journal of Magnesium and Alloys2013，1，4： | 10 |
| 3 | Characterization and Prediction of Microporosity Defect in Sand Cast WE54 Alloy Castings显示文摘In order to study the effect of Zr modification and riser size on microporosity defect distributions in WE54 alloy sand castings,the microporosity volume percentage in Zr-free and Zr-containing WE54 alloy plate castings was determined by density measurement based on Archimedes' principle,and the microstructure of the microporosity defects was observed by optical microscopy and scanning electron microscopy.Then by using Procast software,the Niyama criterion was calculated in order to investigate the validity of Niyama criterion on prediction of microporosity defects in WE54 alloy sand castings.It is found from the density measurement results that Zr addition does not affect the microporosity distributions in WE54 alloy castings.While the distribution area of microporosity defect in the plate castings decreases significantly as the riser size increases.Based on the experimental results,a riser selection principle for production of compact WE54 alloy castings is proposed that the solidification modulus of the riser should be greater than that of the casting by 30%,simply m_r > 1.3m_c.By comparing the experimental and simulating results,it is found that the predicted microporosity regions by Niyama criterion agrees well with experimental results,and a critical Niyama value of0.4 ℃^(0.5) s^(0.5) mm^(-1) is suggested for prediction of microporosity formation in WE54 alloy sand castings. | Jilin Li Rongshi Chen Yuequn Ma Wei Ke | 2014 | Journal of Materials Science & Technology2014，30，10： | 9 |
| 4 | Hot Tearing of Sand Cast Mg-5 wt.% Y-4 wt.% RE (WE54) Alloy显示文摘Hot tearing is a common and severe defect occurring during solidification of castings.The rational understanding of hot tearing formation mechanism is beneficial to the foundry process design.In the present research,a new developed instrumented'CRC'equipment was applied in characterization of hot tearing in sand cast Mg-5 wt.%Y-4 wt.%RE(WE54)alloy with and without Zr addition.Microstructure observation and thermal analysis were carried out to help analyzing the results.The results showed that hot tearing onset occurs at a relatively low solid fraction(fs)in WE54 alloy sand castings,which indicates the participation of remaining liquid during hot tearing formation.Microstructure observation of the hot tearing surface also proves the liquid film existence between solidifying dendrites.The contraction strain caused by casting solidification induces the flowing of remaining liquid between solidifying dendrites and results in formation of interdendritic liquid films.These liquid films are separated by sufcient contraction stress and form hot cracks.The addition of Zr in WE54 alloy significantly refines the alloy microstructure and increases the solid fraction at hot tearing onset,both of which result in increasing of the fracture stress of interdendritic liquid film.Thus the hot tearing susceptibility of WE54 alloy is weakened by Zr addition. | Jilin LI Rongshi CHEN Yuequn MA Wei KE | 2013 | Acta Metallurgica Sinica(English Letters)2013，26，6： | 9 |
| 5 | Cationic content effects of biodegradable amphoteric chitosan-based flocculants on the flocculation properties显示文摘A series of biodegradable amphoteric chitosan-based flocculants(3-chloro-2-hydroxypropyl trimethyl ammonium chloride(CTA) modified carboxymethyl chitosan,denoted as CMC-CTA) with different substitution degrees of CTA were prepared successfully.The content of carboxymethyl groups in each CMC-CTA sample was kept almost constant.The solubility of the various flocculants showed that,higher cationic content of flocculants caused a better solubility.The flocculation experiments using kaolin suspension as synthetic water at the laboratory scale indicated that the substitution degree of CTA was one of the key factors for the flocculation properties.With the increase of cationic content,the flocculants were demonstrated better flocculation performance and lower dosage requirement.Flocculation kinetics model of particles collisions combining zeta potential and turbidity measurements was employed to investigate the effects of the cationic content of the flocculants on the flocculation properties from the viewpoint of flocculation mechanism in detail.Furthermore,flocculation performance using raw water from Zhenjiang part of Yangtze River at the pilot scale showed the similar effects to those at the laboratory scale. | Zhen Yang Yabo Shang Xin Huang Yichun Chen Yaobo Lu Aimin Chen Yuxiang Jiang Wei Gu Xiaozhi Qian Hu Yang Rongshi Cheng | 2012 | Journal of Environmental Sciences2012，24，8： | 8 |
| 6 | Effect of rare earth elements on the structures and mechanical properties of magnesium alloys显示文摘By means of first-principles calculations,we have investigated the effects of rare earth elements (REEs) on the structures and mechanical properties of magnesium.The lattice parameters,elastic constants,bulk moduli,shear moduli,Young's moduli and anisotropic parameter of these solid solutions have been calculated and analyzed.The nearest-neighbor distance between Mg and the REEs is also analyzed to explore the correlation with the bulk moduli.The results show that the 4f-electrons and atomic radii play an important role in the strengthening process.The anomalies of the lattice parameters and mechanical properties at Eu and Yb are due to the half-filled and full-filled 4f-electron orbital states.Finally,the increase of directional bonding character near the alloying elements may account for the anisotropy and brittleness of these magnesium alloys. | L Zhong ZHOU Jian SUN ZhiMei CHEN RongShi | 2013 | Science China(Technological Sciences)2013，56，3： | 8 |
| 7 | Effects of trace Gd concentration on texture and mechanical properties of hot-rolled Mg-2Zn-xGd sheets显示文摘The effects of Gd concentration(0.1,0.3,0.7 wt%)on the microstructure,texture and mechanical properties of rolled and annealed Mg-2Zn-xGd sheets have been investigated aiming to develop low cost and high ductile Mg-Zn-Gd sheets.Dynamic recrystallization,static recrystallization and grain growth during hot rolling process and annealing process were delayed with increase of Gd concentration,leading to fine grain microstructure.The rolled 0.1 wt%Gd sheet showed strong basal texture which remained stable after annealing process and exhibited medium elongation of about 25%.In contrast,the rolled 0.3 wt%Gd sheet had weak basal texture which transformed to non-basal texture with double peaks tilted about±48°to the transverse direction due to the static recrystallization during annealing process.Consequently,the annealed sheets exhibited higher elongation of 40%along the rolling direction and 50%along the transverse direction due to the existence of non-basal texture.It is suggested that the minimum effective concentration for texture randomization in the Mg-2Zn-xGd alloy is about 0.3 wt%. | Hong Yan Rongshi Chen Nan Zheng Jun Luo Shigeharu Kamado Enhou Han | 2013 | Journal of Magnesium and Alloys2013，1，1： | 7 |
| 8 | First-principles calculations of the β'-Mg_7Gd precipitate in Mg-Gd binary alloys显示文摘The metastable β' phase is often the most effective hardening precipitate in Mg-Gd based alloys.In this paper,the structural,elastic and electronic properties of the recently identified β'-Mg7Gd precipitate in Mg-Gd binary alloys were investigated using first-principles calculations based on density functional theory.The lattice mismatches between the coherent β'-Mg7Gd precipitate and α-Mg matrix are discussed and used to rationalize the experimentally observed morphology of the precipitate.The mechanical properties were investigated through analysis of the single-crystal elastic constants and the polycrystalline elastic moduli.It is found that β'-Mg7Gd is brittle in nature.Strong covalent bonding in β'-Mg7Gd,as inferred from its electronic structure,further explains its mechanical properties.Our theoretical results show good agreement with experimental measurements. | GAO Lei ZHOU Jian SUN ZhiMei CHEN RongShi HAN EnHou | 2011 | Chinese Science Bulletin2011，56，11： | 7 |
| 9 | Electronic origin of the anomalous solid solution hardening of Y and Gd in Mg:A first-principles study显示文摘Y and Gd demonstrate anomalous solid solution hardening efficiency,which cannot be understood using the elastic impuritydislocation interaction theory.We performed first-principles calculations to investigate the effect of different alloying elements such as Al,Zn,Y,and Gd on the chemical bonding of Mg solid solutions.The present calculations clearly show that the anomalous solid solution hardening of Y and Gd in Mg may be understood based on the increased bonding strength of both Mg-Y (Gd) and Mg-Mg. | GAO Lei ZHOU Jian SUN ZhiMei CHEN RongShi HAN EnHou | 2011 | Chinese Science Bulletin2011，56，10： | 4 |
| 10 | Biodegradable behaviors of AZ31 magnesium alloy in simulated body fluid显示文摘 | Yingwei Song Dayong Shan Rongshi Chen Fan Zhang En-Hou Han | 2008 | Materials Science & Engineering C2008，，3： | 2 |
| 11 | Superplasticity of Mg-5.8Zn-1Y-Zr alloy sheet fabricated by combination of extrusion and hot-rolling processes显示文摘Superplastic behaviors of quasicrystal phase containing Mg-5.8Zn-1Y-0.48Zr alloy sheets fabricated by combination of extrusion and hot-rolling processes have been investigated at temperature ranging from 623 to 753 K and at the strain rates ranging from 10-4 to 10-2 s-1 by uniaxial tensile tests. An excellent superplasticity with the maximum elongation to failure of 1020% was obtained at 753 K and the strain rate of 1.04×10-3 s-1 and its strain rate sensitivity, m, is as high as up to 0.75. The microstructure was stable during superplastic deformation due to the uniformly distributed fine quasicrystal particles. In addition, micro-cavities and their coalescences were observed in the superplastic deformation of the ZW61 magnesium alloy. Grain boundary sliding (GBS) was considered to be the main deformation mechanism during the superplastic deformation. Dislocation creep controlled by atom diffusion through grain boundaries or interior grains is suggested mainly to accommodate the GBS in super-plastic deformation. | YAN Hong CHEN RongShi HAN EnHou | 2009 | Science China(Technological Sciences)2009，52，1： | 2 |
| 12 | Biodegradable behaviors of AZ31 magnesium alloy in simulated body fluid显示文摘 | Yingwei Song Dayong Shan Rongshi Chen Fan Zhang En-Hou Han | 2008 | Materials Science & Engineering C2008，，3： | 2 |
| 13 | Microstructure and mechanical properties of Mg-Gd-Y-Zr alloy cast by metal mould and lost foam casting 显示文摘 | LI Jilin CHEN Rongshi KE Wei | 2011 | Transactions of Nonferrous Metals Society of China2011，21，： | 1 |
| 14 | Nd : YAG laser welding of 1420 aluminum-lithium alloy显示文摘 | Xiao Rongshi Yang Wuxiong Chen Kai | 2007 | Chinese J Lasers2007，34，1： | 1 |
| 15 | Strength en-hancement of Mg-3Gd-lZn alloy by cold rolling 显示文摘 | Wu Di Tang Weineng Chen Rongshi | 2013 | TransNonferrous Metals Soc China2013，23，： | 1 |
| 16 | Corro-sion characterization of Mg-8Li alloy in NaCl solution显示文摘 | Song Yingwei Shan Dayong Chen Rongshi | 2009 | Corrosion Science2009，51，5： | 1 |
| 17 | Strength enhancement of Mg-3Gd-lZn alloy by cold rolling 显示文摘 | Wu Di Tang Weineng Chen Rongshi | 2013 | Transctions of Nonferrous Metals society of China2013，23，： | 1 |
| 18 | Transactions of Nonferrous Metals Society of China显示文摘 | Yan Hong Chen Rongshi Han Enhou | 2010 | 20:5502010，20，： | 1 |
| 19 | An environmentally friendly molybdate/phosphate black film on Mg–Zn–Y–Zr alloy显示文摘 | Yingwei Song Dayong Shan Rongshi Chen En-Hou Han | 2010 | Surface & Coatings Technology2010，，20： | 1 |
| 20 | Thermal degrada- tion behaviors of cellulose whiskers显示文摘 | Chen Rongshi Wang Neng Ding Enyong | 2007 | Journal of south China uni- versity of technology ( Natural science edition)2007，35，10： | 1 |
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