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Comparison of contribution of sub-rapid cooling and shear deformation to refinement of Fe-rich phase in hypereutectic Al-Fe alloy during rheo-extrusion

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Journal of Iron and Steel Research International 2020年第11期27卷 1294-1302页

作者： Xiang Wang ren-guo guan Yuan-dong Li Ti-jun Chen State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals Lanzhou University of TechnologyLanzhou 730050GansuChina School of Materials Science and Engineering Northeastern UniversityShenyang 110819LiaoningChina

A hypereutectic Al-3Fe(wt.%)alloy was subjected by rheo-extrusion,and the effect of sub-rapid cooling and shear deformation on the refinement of Fe-rich phase was *** results showed that both the primary Fe-rich phase and eutectic Fe-rich phase in the solidified Al-Fe alloy were finer than the platelike Fe-rich phase in the as-cast Al-Fe alloy with the same content of *** solidified Al-Fe alloy was subjected to three stages of shear deformation,and both the primary Fe-rich phase and eutectic Fe-rich phase were fractured and the average length was refined to 400 nm,while Fe-rich phase in the as-cast Al-3Fe(wt.%)alloy was platelike and its average length was 40 *** tensile strength and elongation of the hypereutectic Al-3Fe(wt.%)alloy containing nanosized Fe-rich phase were 162 MPa and 25.78%while those of the as-cast AI-3Fe(wt.%)alloy containing coarse platelike Fe-rich phase were 102 MPa and 16.84%,*** the refineme nt of Fe-rich phase in hypereutectic Al-Fe alloy during rheo-extrusion,the three stages of shear deformation contributed more than sub-rapid cooling.

关键词： Fe-rich phase Hypereutectic Al-Fe alloy Refinement Sub-rapid cooling Shear deformation

Semisolid die forging process,microstructures and properties of AZ31 magnesium alloy mobile telephone shells

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International Journal of Minerals,Metallurgy and Materials 2011年第6期18卷 665-670页

作者： ren-guo guan Li-qing Chen Fu-rong Cao Zhan-yong Zhao Yong ren College of Materials and Metallurgy Northeastern University Shenyang 110004 China State Key Lab of Rolling and Automation Northeastern University Shenyang 110004 China

A semisolid slurry of AZ31 magnesium alloy was prepared by vibrating wavelike sloping plate process,and the semisolid die forging process,microstructures,and properties of the magnesium alloy mobile telephone shell were *** semisolid forging process was performed on a YA32-315 four-column universal hydraulic *** microstructures were observed by optical microscopy,the hardness was analyzed with a model 450SVD Vickers hardometer,the mechanical properties was measured with a CMT5105 tensile test machine,and the fractograph of elongated specimens was observed by scanning electron microscopy （SEM）.The results reveal that with the increase of die forging force,the microstructures of the product become fine and dense.A lower preheating temperature and a longer dwell time are favorable to the formation of fine and dense *** optimum process conditions of preparing mobile telephone shells with excellent surface quality and microstructures are a die forging force of 2000 kN,a die preheating temperature of 250℃,and a dwell time of 240 *** solution treatment at 430℃ and aging at 220℃ for 8 h,the Vickers hardness is 61.7 and the ultimate tensile strength of the product is *** fractographs show the mixing mechanisms of quasi-cleavage fracture and ductile fracture.

关键词： magnesium alloys semisolid forging microstructure mechanical properties fracture

Shear Model of Metal Melt Flowing on Vibration Wall and Effect of Shear Stress on Solidification Microstructure

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Acta Metallurgica Sinica(English Letters) 2018年第6期31卷 650-658页

作者： ren-guo guan Xiang Wang Ying-Qiu Shang Di Tie Run-Ze Chao School of Materials Science and Engineering Northwestern Polytechnical University Xi'an 710072 China School of Materials Science and Engineering Northeastern University Shenyang 110819 China Luoyang Ship Material Research Institute Luoyang 471000China

In this work,the shear model of metal melt flowing on vibration surface is established,and coupling effects of vibration and shear on the distribution of shear stress in melt and melt solidification microstructure are *** results show that the transition of melt from laminar flow to turbulent flow occurs earlier with increasing vibration frequency and vibration *** the laminar flow melt,shear stress in melt decreases with increasing vertical length,but it decreases firstly and then stabilizes with increasing flow *** the turbulent flow melt,shear stress decreases firstly and then stabilizes with increasing vertical length,but it increases with increasing flow *** the increase in vibration frequency and amplitude,shear stress along flow direction in laminar flow melt increases,while shear stresses along both flow direction and vertical direction in turbulent flow melt *** stress in melt decreases with increasing length along vertical *** the increase in flow length,shear stress decreases firstly and then stabilizes in laminar flow melt,while it increases in turbulent flow *** the increase in vibration frequency and amplitude,shear stress increases in laminar flow melt,while it stabilizes in turbulent flow *** on theoretical calculation,the maximum shear stress in melt during vibration shear flow is always much lower than the yield strength of a-Al grain,so the shear stress induced by vibration shear flow cannot break columnar crystal,which agrees with the experiment ***,the model can explain the shear constitutive relation of melt flow on vibration surface relatively well.

关键词： Solidification Flow near surface Shear Vibration Columnar crystal

Effects of Process Parameters of Semisolid Stirring on Microstructure of Mg–3Sn–1Mn–3SiC(wt%) Strip Processed by Rheo-rolling

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Acta Metallurgica Sinica(English Letters) 2017年第1期30卷 66-72页

作者： Zhan-Yong Zhao ren-guo guan Jian-Hong Zhang Zhou-Yang Zhao Pei-Kang Bai School of Materials Science and Engineering North University of China School of Materials Science and Engineering Northeastern University

A novel semisolid stirring and rheo-rolling process for preparing Mg-3Sn-1Mn-3SiC （wt%） composite strips was proposed, and the effects of process parameters of semisolid stirring on microstructures of Mg-3Sn-1Mn-3SiC （wt%） composite strips were investigated. The average grain size and roundness decrease, and the distribution of SiC becomes more homogeneous with the decrease in stirring temperature and the increase in the stirring speed. When the stirring time is increased, the distribution of SiC particles tends to be homogeneous, and the average grain diameter and roundness of α- Mg grain decrease. Under the following process parameters： the stirring temperature at 640 ℃, the stirring speed at 1100 rpm, the stirring time at 30 min and the roll speed at 0.2 m/s, Mg-3Sn-1Mn-3SiC （wt%） strip with a cross-sectional size of 4 mm × 160 mm was prepared. The ultimate tensile strength and elongation of Mg-3Sn-1Mn-3SiC （wt%） composite strip reached 226 ± 6 MPa and （7.4 ± 0.2）%, which are obviously improved in comparison with Mg-3Sn-1Mn （wt%）.

关键词： Mg-matrix composite Rheo-rolling Microstructure Property

Effect of mixing temperature on microstructure of an Al-Si alloy prepared by controlled diffusion solidification

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China Foundry 2023年第3期20卷 241-252页

作者： Han Xue Ti-jun Chen Xue-zheng Zhang guang-li Bi Ying Ma ren-guo guan State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals Lanzhou University of TechnologyLanzhou 730050China School of Materials Science and Engineering Dalian Jiaotong UniversityDalian 116028LiaoningChina

The effects of mixing temperature,i.e.,the temperatures of two precursor melts(pure Al and Al-12Si),on the temperature and solute fields of resultant mixture,the nucleation and growth,and the size and morphology of primary grains during controlled diffusion solidification(CDS) of Al-8Si alloy were investigated by using simulation and *** results indicate that a lower mixing temperature is helpful for achieving more supercooled microscale Al-rich pockets in the mixture,and increasing the width and supercooling degree of supercooling zone in the Al-rich pockets,and thus,the nucleation *** nuclei grow up in nondendritic mode,resulting in spheroidal,at least,nondendritic *** a successful CDS,the superheat degrees of the two precursor melts should be limited within several degrees,and it is not necessary to extra stipulate the superheat degree of target alloy melt(Al-8Si) when the requirement about Gibbs energies of the three melts is *** observation on casting microstructures shows that the employed simulation and calculation processes are reasonable and the achieved results are reliable.

关键词： controlled diffusion solidification Al-Si alloy nucleation and growth supercooling nondendritic grains

Microstructure and properties of A2017 alloy strips processed by a novel process by combining semisolid rolling,deep rolling,and heat treatment

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International Journal of Minerals,Metallurgy and Materials 2013年第8期20卷 770-778页

作者： ren-guo guan Xiang Wang Zhan-yong Zhao Wei-wei Wang Fu-rong Cao Chun-ming Liu College of Materials and Metallurgy Northeastern University

A novel short process for producing A2017 alloy strips with notable features of near net shape, saving energy, low cost, and high product performance was developed by combining semisolid rolling, deep rolling, and heat treatment. The microstructure and properties of the A2017 alloy strips were investigated by metallographic microscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, tensile testing, and hardness measurement. The cross-sectional microstructure of the A2017 alloy strips is mainly composed of near-spherical primary grains. Many eutectic phases CuA12 formed along primary grain boundaries during semisolid rolling are crushed and broken into small particles. After solution treatment at 495℃ for 2 h the eutectic phases at grain boundaries have almost dissolved into the matrix. When the solution treatment time exceeds 2 h, grain coarsening happens. More and more grain interior phases precipitate with the aging time prolonging to 8 h. The precipitated particles are very small and distribute homogenously, and the tensile strength reaches its peak value. When the aging time is prolonged to 12 h, there is no obvious variation in the amount of precipitated phases, but the size and spacing of precipitated phases increase. The tensile strength of the A2017 alloy strips produced by the present method can reach 362.78 MPa, which is higher than that of the strips in the national standard of China.

关键词： aluminum alloys semisolid rolling heat treatment microstructure mechanical properties

Mathematic model of rolling pressure during a semisolid shearing-rolling process

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International Journal of Minerals,Metallurgy and Materials 2012年第12期19卷 1121-1127页

作者： ren-guo guan Zhan-yong Zhao Chao Lian Qiu-sheng Zhang Chun-ming Liu College of Materials and Metallurgy Northeastern UniversityShenyang 110819China

A mathematic model of rolling pressure during a novel semisolid shearing-rolling process was established. The rolling pressure in this process is higher than that in the conventional rolling. The increment of rolling pressure in the backward slip zone is higher than that in the forward slip zone, and the neutral plane moves toward to the roll gap entrance. The maximum and the average rolling pressures increase with the decrease of strip thickness, and the effects of strip thickness on the rolling pressure is more obvious in the forward slip zone than in the backward slip zone. Meanwhile, the neutral plane moves toward the roll gap exit with the decrease of strip thickness. The maximum and average rolling pressures increase with the decrease of strip width, and the strip width affects the pressure more obviously in the backward slip zone than in the forward slip zone. At the same time, the neutral plane moves toward the roll gap entrance with the decrease of strip width. The maximum and average rolling pressures increase with increasing roll radius, and the neutral plane moves toward the roll gap exit.

关键词： semisolid rolling pressure mathematic models strips magnesium alloys

Characteristics of interfacial reactions between Ti-6Al-4V alloy and ZrO2 ceramic mold

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China Foundry 2020年第6期17卷 409-415页

作者： Shi-chen Sun Er-tuan Zhao Chen Hu Jin-rui Yu Yu-kun An ren-guo guan School of Mechanical Engineering Shandong University of TechnologyZibo 255022China School of Materials Science and Engineering Dalian JiaoTong UniversityDalian 116028China

The interfacial reaction between Ti-6Al-4V alloy and ZrO2 ceramic mold with zirconia sol binder was investigated by keeping the 12 g alloy melt in a vacuum induction furnace for 15 *** microstructures,element distribution and phase constitution of the interface were identified by optical microscopy(OM),scanning electron microscopy(SEM)equipped with energy dispersive spectroscopy(EDS)and X-ray diffraction(XRD).The results show that the whole interface reaction layer can be divided into three regions:metal penetration layer,transition layer,and hardened layer according to the structure morphology,which has the characteristics of severe metal penetration,finer lamellar,and coarse oxygen-richαphase,*** erosion of the alloy melt on the ceramic mold promotes the decomposition of zirconia,which leads to the increase of local Zr concentration,greatly increasing the activity coefficient of Ti,aggravating the occurrence of interfacial ***,the interfacial reaction shows the characteristics of chain *** the oxygen released by the dissolution of zirconia exceeds the local solid solubility,it precipitates in the form of bubbles,resulting in blowholes at the *** result also indicates that the zirconia mold with zirconia sol binder is not suitable for pouring heavy titanium alloy castings.

关键词： titanium alloy interfacial reaction ZrO2 ceramic mold activity coefficient

Molecular dynamics simulations of helium transport through inorganic mineral nanopores

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Science China Earth Sciences 2025年第1期68卷 237-252页

作者： Dandan SONG Ping guan Chi ZHANG Jiahao ren School of Earth and Space Sciences Peking UniversityBeijing100871China

Helium transport through nanoscale inorganic mineral pores and pore throats is essential for its overall *** elucidate helium's transport dynamics within nanopores,we employed equilibrium and non-equilibrium molecular dynamics simulations to investigate helium's static self-diffusion and pressure-driven flow in quartz slit-shaped *** also introduced water and various gases,including hydrogen,methane,ethane,nitrogen,and carbon dioxide,into the nanopores to assess their influence on helium *** findings indicate minimal helium adsorption on quartz pore *** conditions where the pore size is less than 5 nm and the pressure under 10 MPa,environmental factors markedly influence helium *** pore sizes,high temperatures,and low gas pressures enhance helium desorption and facilitate faster *** observed a positive correlation between helium flow velocity and factors such as pore size,pressure gradient,and surface smoothness of the ***,the presence of pore water and carrier gases in quartz nanopores,which diffuse more slowly than helium,tends to reduce helium surface adsorption and slow its *** the carrier gases studied,nitrogen showed similar adsorption capacity,diffusivity,and stability to helium,while carbon dioxide displayed the highest adsorption capacity and the slowest diffusion rate,markedly differing from *** on the simulation results,we concluded that water and carrier gases primarily function as transport mediums in helium migration,moving together with ***,which shares similar properties with helium,effectively assists in this co-migration ***,carbon dioxide,due to its high adsorption capacity and slow diffusion,tends to be lost during *** a result,gas reservoirs with high nitrogen levels and low carbon dioxide levels are more likely to have higher helium ***,the smaller pore sizes and higher gas pressures in caproc

关键词： Helium transport Slit nanopores Molecular dynamics simulations Diffusion Flow carriers