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39篇 您的检索式:作者名="Qichi Le"
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1Effect of homogenization treatment on microstructure evolution and the distributions of RE and Zr elements in various MgeLieREeZr alloys显示文摘Mge3Lie0.4Zr alloys containing RE elements(Gd,La,Nd)(Mge3LieREe0.4Zr alloys)are investigated to reveal the influence of homogenization treatment on microstructures and distributions of RE,Zr elements.It is found that 300C24 h homogenization treatment shows better improvement on the microstructure including the refinement of grain size,the dispersion of cellular dendrite and low melting point particles.Before treatment,La and Nd segregate effectively at grain boundary and Zr segregates in the form of precipitates.Homogenization treatment induces the reduction of RE segregation.However,the segregation of Zr in precipitates cannot be abated due to the relatively low diffusion rate compared with RE elements.Lei Bao Qichi Le Zhiqiang Zhang Jianzhong Cui Qinxue Li 2013Journal of Magnesium and Alloys2013,1,2:10
2Role of pre-vertical compression in deformation behavior of Mg alloy AZ31B during super-high reduction hot rolling process显示文摘Mg alloy AZ31 B plates were processed by hot rolling with different thickness reductions per pass and prevertical compression followed by super-high reduction hot rolling(PVCR), respectively. Microstructure evolution, rolling formability variation and mechanical responses were investigated. As reduction per pass increased, the number of shear bands deflecting toward rolling direction increased, resulting in easy crack initiation in and around the bands. With increasing reduction per pass up to 80%, twinning and twinning-induced dynamic recrystallization(DRX) dominated the deformation of the edge material at350?C, resulting in local recrystallization with coarse grains and further largest edge-crack degree. Preinduced {10ī12} tensile twins by pre-vertical compression(PVC) increased number density of nucleation sites for dynamic recrystallization during the subsequent severe rolling, which enhanced the dominant role of continuous dynamic recrystallization. Designed PVCR-b was proved to be a relatively effective method to improve rolling formability of rolled Mg alloy AZ31 B plates. With this method, mean grain size of AZ31 B plate was significantly refined from ~600 mm to ~14.1 mm and more homogeneous grain size distribution along transverse direction(TD) was achieved. In addition, basal texture intensity was greatly weakened. As a result, tensile anisotropy was distinctly decreased and fracture elongation increased dramatically.Weitao Jia Qichi Le Yan Tang Yunpeng Ding Fangkun Ning Jianzhong Cui 2018Journal of Materials Science & Technology2018,34,11:8
3Effects of Extrusion Speed on the Microstructure and Mechanical Properties of Mg-9Gd-3Y-1.5Zn-0.8Zr alloy显示文摘The effects of the extrusion speed on the microstructures,mechanical properties and aging hardening behaviors of Mg—9Gd—3Y—1.5Zn—0.8Zr alloy have been investigated.The microstructure evolution during hot extrusion has also been discussed.The microstructures of the extruded alloys mainly consist of the equiaxed dynamically recrystallized grains and fiber-like long period stacking ordered(LPSO)phase.The increasing extrusion speed results in grain coarsening and the mechanical properties deterioration.Meanwhile,it could also retard the aging hardening response.The extrudability of the investigated alloy is limited.Cracks nucleate and grow up rapidly when the extrusion speed is over 0.3 m/min.It should be closely related to the large amount of LPSO phase and the unique microstructure evolution.The rapidly precipitating fine lamella during extrusion could pin the dislocations and grain boundaries effectively.It could strengthen the alloy but also limit the extrudability of the investigated alloy.Xuan Liu Zhiqiang Zhang Wenyi Hu Qichi Le Lei Bao Jianzhong Cui 2016Journal of Materials Science & Technology2016,32,4:7
4Effects of Nd/Gd value on the microstructures and mechanical properties of Mg-Gd-Y-Nd-Zr alloys显示文摘Four Mg–Gd–Y–Nd–Zr alloys were prepared by mold casting to investigate the effects of Nd/Gd ratios on microstructures and mechanical properties.The as-cast alloys mainly consist ofα-Mg andβ-Mg5(GdYNd).Volume fractions of the second phase increase and grains were slightly refined with the rising Nd/Gd ratio,when the alloying addition is equal.Meanwhile,fibers of second phase also increase in the extruded alloys when the Nd/Gd value increases.However,the Nd/Gd ratio could hardly influence the mechanical properties of the extruded alloys.The aging hardening response of the extruded alloy differs due to different Nd/Gd ratios.The potential mechanisms have also been discussed in detail.Xuan Liu Zhiqiang Zhang Qichi Le Lei Bao 2016Journal of Magnesium and Alloys2016,4,3:5
5Microstructural and mechanical response of ZK60 magnesium alloy subjected to radial forging显示文摘Radial forging(RF)is an economical manufacturing forging process,in which four dies arranged radially around the workpiece simultaneously act on the workpiece with high-frequency radial movement.In this study,a ZK60 magnesium alloy step-shaft bar was processed under different accumulated strains by RF at350℃.The deformation behavior,microstructure evolution,and mechanical responses of this bar were systematically investigated via numerical simulations and experiments.At the early deformation stage of forging,the material undergoes pronounced grain refinement but an inhomogeneous grain structure is formed due to the strain gradient along the radial direction.The grains in different radial parts were gradually refined by increasing the RF pass,resulting in a bimodal grained structure comprising coarse(~14.1μm)and fine(~2.3μm)grains.With the RF pass increased,the initial micro-sizeβ-phases were gradually crushed and dissolved into the matrix mostly,eventually evolving to form a higher area fraction of nano-sized Zn2 Zr spheroidal particles uniformly distributed through the grain interior.The texture changed as the RF strain increased,with the c-axes of most of the deformed grains rotating in the RD.Additionally,excellent mechanical properties including higher values of tensile strengths and ductility were attained after the three RFed passes,compared to the as-received sample.Jingfeng Zou Lifeng Ma Weitao Jia Qichi Le Gaowu Qin Yuan Yuan 2021Journal of Materials Science & Technology2021,,24:4
6Influence of high-intensity ultrasonic treatment on the phase morphology of a Mg-9.0wt.%Al binary alloy显示文摘The effect of ultrasonic treatment on the β-phase (Mg17Al12) morphology of an Mg-9.0wt.%Al alloy was studied. The result shows that with high-intensity ultrasonic vibration employed during the solidifying of Mg-9.0wt.%Al, the β-phase in the entire cross section of the billet is significantly refined and also changed from continuous to discontinuous morphology. Spherical β-phase is formed during the solidification of the billet treated with high-intensity ultrasonic vibration.ZHANG Zhiqiang LE Qichi CUI Jianzhong 2009Rare Metals2009,28,1:4
7Numerical simulation of DC casting of AZ31 magnesium slab at different casting speeds显示文摘A mathematical model of the direct chill(DC)casting process for AZ31magnesium slab has been developed to predict the temperature evolution in the slab.The temperature fields at different casting speeds were compared and the optimum casting speed of 300 mm×800 mm magnesium slab in the certain pouring temperature and cooling-water flow rate was obtained.The casting speed during the plant trial was consistent with the calculation.Wenyi Hu Qichi Le Zhiqiang Zhang Lei Bao Jianzhong Cui 2013Journal of Magnesium and Alloys2013,1,1:4
8Reducing the yield asymmetry in Mg-5Li-3Al-2Zn alloy by hot-extrusion and multi-pass rolling显示文摘Reducing the yield asymmetry is very important concern for wrought Mg-Li alloys.In this study,Mg-5Li-3Al-2 Zn(LAZ532)alloy was successfully produced by hot-extrusion followed by multi-pass rolling at 573 K.Microstructure evolution,mechanical properties and yield asymmetry reducing of LAZ532 alloys at different rolling passes were studied.By observing microstructure using transmission electron microscopy showed that a small amount of ultra-fine Al Mg_(4)Zn_(11)and nano Li_(3)Al_(2) phases existed in the alloy.With the increasing of rolling passes,the grains of the alloys were obviously refined,and comprehensive mechanical properties were dramatically improved.Meanwhile,it also showed an excellent tension and compression yield symmetry(TYS/CYS was about 1).The results showed that the combined action of the weak{0001}basal lamellar texture,grain refinement and addition of Li element could effectively improve the yield symmetry.Furthermore,based on theoretical analysis,the yield strength in the alloys mainly depended on the strengthening contributions of LAGBs and HAGBs,and strengthening effect of HAGBs most(~50%)to the yield strength improvement.Xiaoqiang Li Liang Ren Qichi Le Lei Bao Peipeng Jin Ping Wang Chunlong Cheng Xiong Zhou Chenglu Hu 2021Journal of Magnesium and Alloys2021,9,3:4
9Effects of casting process on microstructures and flow stress behavior of Mg-9Gd-3Y-1.5Zn-0.8Zr semi-continuous casting billets显示文摘Mg-9Gd-3Y-1.5Zn-0.8Zr alloys own high strength,good heat and corrosion resistance.However,it is difficult for the fabrication of large-scale billets,due to the poor deformation ability and strong hot-crack tendency.This work investigated the casting process on the microstructures and flow stress behaviors of the semi-continuous casting billets for the fabrication of large-scale Mg-9Gd-3Y-1.5Zn-0.8Zr billets.The casting process(electromagnetic intensity and casting speed)shows outstanding effects on the microstructures and flow stress behavior of the billets.The billets with the specific casting process(I=68 A,V=65 mm/min)exhibit uniform microstructures and good deformation uniformity.Xuan liu Qichi Le Zhiqiang Zhang Lei Bao Zhengxing Fan Jianzhong Cui 2014Journal of Magnesium and Alloys2014,2,4:3
10Investigation of Portevin–Le Chatelier effect in rolled α-phase Mg-Li alloy during tensile and compressive deformation显示文摘Avoiding the Portevin-Le Chatelier(PLC)effect is very important concern for wrought Mg-Li alloys.In this study,the special PLC effect was found in rolled Mg-5Li-3Al-2Zn(LAZ532)alloy during tensile and compressive deformation.By observing microstructure evolution of the alloy during tensile and compressive deformation,it was found that prismaticand pyramidalslips were activated during tensile deformation,resulting in plenty of dislocation accumulation.In the deformation process after compressive yielding,the deformations in coarse grains and fine grains were dominated by{1012}extension twinning and grain boundary slip,respectively.Based on experimental result analysis,the sudden appearance of PLC effect in the later stage of axial tensile deformation(along rolled direction)was caused by interaction between solute atoms and dislocations.In the process of axial compressive deformation(along rolled direction),PLC effect presented the complex and changeable phenomenon of appeared-disappeared-appeared,which was mainly caused by the continuous nucleation of twin in the material,the activation of grain boundary slip and the shear deformation of twin,respectively.Xiaoqiang Li Chunlong Cheng Qichi Le Lei Bao Peipeng Jin Ping Wang Liang Ren Hang Wang Xiong Zhou Chenglu Hu 2020Journal of Materials Science & Technology2020,52,17:3
11Macro-physical field of large diameter magnesium alloy billet electromagnetic direct-chill casting:A comparative study显示文摘A comprehensive two-dimensional axisymmetric mathematical model that couples transient electromagnetic force with fluid flow,heat transfer,and solidification was established to describe the interaction of multiphysics field during DC casting.The melt flow,heat transfer,and solidification characteristics under differential phase pulse magnetic field and differential phase low-frequency electromagnetic field(DP-PMF and DP-LFEF)were numerically investigated by means of numerical simulation during electromagnetic direct-chill(DC)casting of AZ31 alloy at the same casting conditions.The effects of differential phase electromagnetic fields on Lorentz forces distributions,melt flow,heat transfer,and liquid sump shape were discussed systematically.Based on measured current waveform,the results were compared with those obtained without magnetic field(MF)and under conventional pulse magnetic field(PMF)and low-frequency electromagnetic field(LFEF)under the same conditions.The results show that the application of magnetic fields can significantly change the solidification process of DC casting.Differential phase magnetic fields(DP-LFEF and DP-PMF)can effectively reduce the temperature of the melt in the liquid sump,and the shallower liquid sump depth can be obtained under the differential phase magnetic fields.A large velocity vibration amplitude and a lower temperature are available simultaneously under DP-PMF,resulting in more uniform temperature distribution.Yonghui Jia Xingrui Chen Qichi Le Hang Wang Lei Bao 2020Journal of Magnesium and Alloys2020,8,3:3
12Effect of REs(Y,Nd)addition on high temperature oxidation kinetics,oxide layer characteristic and activation energy of AZ80 alloy显示文摘The oxidation behaviors of AZ80,AZ8O-0.32 Y and AZ8O-0.38 Nd(wt.%)alloys were researched at 413℃,420℃,427v and 433℃for up to 6 h in air environment via a high precision analytical balance,a laser confocal microscope,differential scanning calorimeter(DSC)analysis,X-ray diffraction(XRD)analysis,scanning electron microscope(SEM)observation,and X-ray photoelectron spectroscopy(XPS)analysis.The results show that the weight gain and oxidation rate of AZ80 are reduced significantly,the initiation form and propagation of cracks in oxide layer are changed.Compact and protective oxide layer forms on alloy surface with Y or Nd addition.And the activation energies of AZ80,AZ80-0.32Y and AZ8O-0.38Nd alloys calculated via Arrhenius equation are 82.556 kJ/mol,177.148kJ/mol and 136.738 kJ/mol,respectively.Chunlong Cheng Xiaoqiang Li Qichi Le Ruizhen Guo Qing Lan Jianzhong Cui 2020Journal of Magnesium and Alloys2020,8,4:3
13Optimum rolling speed and relevant temperature-and reduction-dependent interfacial friction behavior during the break-down rolling of AZ31B alloy显示文摘The present study aimed to determine the optimum rolling speed for break-down rolling of as-cast AZ31 B alloy and investigated the friction behavior associated with temperature-and reduction-sensitivity at the roll/plate contact interface. Tensile testing, formability evaluation and microstructural studies relevant to different rolling speeds were performed and finally the optimum operating rolling speed(50.0 ± 0.8 m/min) was obtained. Further, the effects of rolling reduction and initial temperature were assessed on the temperature variation, lateral spread and interfacial friction behavior at optimum rolling speed. The results showed that lower rolling speed(18.0 ± 0.8 m/min) resulted in an incompletely recrystallized structure where twins occupied relatively high volume fraction. Twinning dominated the deformation at rolling speed exceeding the optimum, resulting in the local recrystallization with shear bands and coarse grains. Rolling at 50.0 ± 0.8 m/min could get the best overall tensile properties and rolling formability due to the relatively high recrystallization degree and microstructure uniformity. An inverse method has been developed to determine the interfacial friction coefficient during interaction of AZ31 B alloy with roll surfaces. When rolling at the optimum speed, the interfacial friction coefficient ranged from 0.16 to 0.58, which was strongly positively correlated with the reduction but slightly positively correlated with the initial temperature. Depended on the rolling characteristics, external friction effect coefficient ranged from 1.25 to 2.35 and it exhibited positive correlation with both the initial rolling temperature and rolling reduction.Weitao Jia Yan Tang Fangkun Ning Qichi Le Lei Bao 2018Journal of Materials Science & Technology2018,34,11:2
14Bauschinger-Like Effect of AZ31 Magnesium Alloy Wide Sheet During the Straightening Process显示文摘The Bauschinger-like effect, which showed up in the straightening process of the AZ31 magnesium alloy wide sheet, was investigated through the multi-pass discrete three-point bending–unloading–bending(BUB) experiments. The stress variable, anisotropy, and asymmetry of tension and compression on the straightening process were corresponding to the Bauschingerlike effect. The Bauschinger-like effect in the initial, intermediate, and end of the straightening process was dominated by the twinning, detwinning, and dislocation induced by pyramidal < c + a > slip, respectively. Also, they were responsible for the transformation of the Bauschinger stress parameter(BSP) and Bauschinger energy parameter(BEP). Later, the anisotropic nonlinear kinematic hardening model(ANK model) to describe the Bauschinger-like effect was optimized and simplified.Fangkun Ning Qichi Le Yonghui Jia Liang Chen 2021Acta Metallurgica Sinica(English Letters)2021,34,9:2
15Efects of low frequency electromagnetic ield on surface quality, microstructure and hot-tearing tendency of semi-continuous casting ZK60 magnesium alloy billets显示文摘The low frequency electromagnetic field was applied during direct chill(DC) semi-continuous casting of the ZK60 magnesium alloy billets. Effects of low frequency electromagnetic field on surface quality, microstructure and hot-tearing tendency of Φ500 mm ZK60 magnesium alloy billets were investigated. The results showed that with the application of the low frequency electromagnetic field, the surface quality of the ZK60 magnesium alloy billets is markedly improved and the depth of cold fold is decreased. The microstructure of the billets is also significantly refined. Besides, the distribution of the grain size is relatively uniform from the billet surface towards its center, where the average grain size is 42 μm at surface and 50 μm at center. It also shows that the hot-tearing tendency of DC semi-continuous casting ZK60 magnesium alloy billets is significantly reduced under low frequency electromagnetic field.Zhang Zhiqiang Le Qichi Bao Lei Cui Jianzhong 2013China Foundry2013,10,6:2
16Effects of electromagnetic field and lubricate condition on the surface quality of magnesium alloy billet during LFEC processing显示文摘The microstructures of the magnesium billets could be improved markedly by low-frequency electro-magnetic casting (LFEC) processing. In fact, the low-frequency electromagnetic field (LFEF) also has favorite effect on the surface quality of billet. However, few public reports on the surface quality of LFEC magnesium billets could be found. Therefore, a new crystallizer with a metal internal sleeve to-gether with a kind of lubricant was designed aiming at lowing surface turning quantity, and the effects of casting velocity, electromagnetic condition and lubrication on the surface quality of magnesium billets were investigated. The results indicate that LFEF together with the lubricate condition would be responsible for the surface quality of the billets, and the high surface quality billets could be achieved by optimizing the casting conditions.QiChi Le ZhiQiang Zhang JianZhong Cui 2009Science China(Technological Sciences)2009,52,1:2
17Numerical simulation of electromagnetic DC casting of magnesium alloys显示文摘Le Qichi Guo Shijie Zhao Zhihao 2007Journal of Materials Processing Technology2007,,183:1
18Understanding on corrosion mechanism of oxidized AZW800 alloy in 3.5 wt%NaCl solution显示文摘Magnesium alloys are more widely used at higher temperatures.However,it is not well known whether oxide layer,produced at high temperature,could show corrosion protection.Thus,the corrosion behaviors of oxidized AZW800 alloy were investigated by hydrogen evolution and electrochemical measurements to evaluate effect of oxide layer on corrosion resistance.The results showed that corrosion of removed oxide layer AZW800 alloy showed characteristic of localized corrosion,leaving randomly bulky pits.While reserved oxide layer AZW800 alloy exhibited a relatively uniform corrosion.The results indicated that oxide layer could hinder corrosion of oxidized AZW800 alloy in the initial period of immersion.While subsequently,aggravated corrosion would occur owing to defects of oxide layer and less protective products film.Besides,present of oxide layer eliminated micro-galvanic couple on alloy surface.The synergistic effect of elimination of micro-galvanic couple on alloy surface and alkalization effect transforms localized corrosion into relatively uniform corrosion of alloys.Chunlong Cheng Qichi Le Liang Chen Wenxin Hu Tong Wang Baosong Zhu Xiong Zhou 2023Journal of Magnesium and Alloys2023,11,5:1
19Effects of Y Content on the Microstructures and Mechanical Properties of Mg-5Zn-xY-0.6Zr Alloys显示文摘Three as-cast and as-extruded Mg-5Zn-x Y-0.6Zr(x=5 wt%, 8 wt%, 11 wt%) alloys were prepared, and the effects of Y content on the microstructures and mechanical properties of the alloys were investigated. The results show that the investigated Mg-Zn-Y-Zr alloys mainly consist of a-Mg, X-Mg12 YZn and minor amount of W-Mg_3Y_2Zn_3 phases. The volume fraction of X-Mg_(12) YZn phase increases and that of W-Mg_3Y_2Zn_3 phase decreases with the rising of Y content in the alloys. The as-extruded Mg-5Zn-11Y-0.6Zr alloy owns the optimal ultimate tensile strength and yield strength of 429 and 351 MPa, respectively. Mg-5Zn-5Y-0.6Zr alloy owns the maximum elongation of 13.6%.尹思奇 张志强 LIU Xuan ZHU Zhenjia BAO Lei LE Qichi CUI Jianzhong 2019Journal of Wuhan University of Technology(Materials Science)2019,34,1:1
20Materials and Design显示文摘Shao Zhiwen Le Qichi Zhang Zhiqiang 201132:42162011,32,:1
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