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Two-dimensional cellular automaton model for simulating structural evolution of binary alloys during solidification

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Transactions of Nonferrous Metals Society of China 2006年第6期7卷 1410-1416页

作者：张林张彩碚 School of Science Northeastern University

Two-dimensional cellular automaton(CA)simulations of phase transformations of binary alloys during solidification were reported.The modelling incorporates local concentration and heat changes into a nucleation or growth function,which is utilized by the automaton in a probabilistic fashion.These simulations may provide an efficient method of discovering how the physical processes involved in solidification processes dynamically progress and how they interact with each other during solidification.The simulated results show that the final morphology during solidification is related with the cooling conditions.The established model can be used to evaluate the phase transformation of binary alloys during solidification.

关键词： binary alloys phase transformation solidification diffusion nucleation computer simulation cellular

Microstructure and mechanical properties of novel Al-Y-Sc alloys with high thermal stability and electrical conductivity

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Journal of Materials Science & Technology 2020年第1期36卷 1-6页

作者： A.V.Pozdniakov R.Yu.Barkov NUST"MISiS" Leninskiy ave.4119049MoscowRussia

The microstructure and mechanical properties of novel Al-Y-Sc alloys with high thermal stability and electrical conductivity were investigated.Eutectic Al3 Y-phase particles of size 100-200 nm were detected in the as-cast microstructure of the alloys.Al3 Y-phase particles provided a higher hardness to as cast alloys than homogenized alloys in the temperature range of 370-440℃.L12 precipitates of the Al3(ScxYy) phase were nucleated homogenously within the aluminium matrix and heterogeneously on the dislocations during annealing at 400℃.The average size of the L12 precipitates was 11±2 nm after annealing for 1 h,and 25-30 nm after annealing for 5 h,which led to a decrease in the hardness of the Al-0.2 Y-0.2 Sc alloy to15 HV.The recrystallization temperature exceeded 350℃and 450℃for the Al-0.2 Y-0.05 Sc and Al-0.2 Y-0.2 Sc alloys,respectively.The investigated alloys demonstrated good thermal stability of the hardness and tensile properties after annealing the rolled alloys at 200 and 300℃,due to fixing of the dislocations and grain boundaries by L12 precipitates and eutectic Al3 Y-phase particles.The good combination of strength,plasticity,and electrical conductivity of the investigated Al-0.2 Y-0.2 Sc alloys make it a promising candidate for electrical conductors.The alloys exhibited a yield stress of 177-183 MPa,ultimate tensile stress of 199-202 MPa,elongation of 15.2-15.8%,and electrical conductivity of 60.8%-61.5% IACS.

关键词： Aluminium alloys Scandium Yttrium Recrystallization Mechanical properties Electrical conductivity

Research Progress on the Corrosion Behavior of Magnesium-Lithium-Based alloys: A Review

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Acta Metallurgica Sinica(English Letters) 2019年第1期32卷 1-9页

作者： Bao-Jie Wang Ji-Yu Luan Dao-Kui Xu Jie Sun Chuan-Qiang Li En-Hou Han School of Environmental and Chemical Engineering Shenyang Ligong University Key Laboratory of Nuclear Materials and Safety Assessment Institute of Metal Research Chinese Academy of Sciences Environmental Corrosion Center Institute of Metal ResearchChinese Academy of Sciences

In this review paper, the research progress on corrosion behavior of hexagonal close-packed(HCP) singular phase, body cubic-centered(BCC) singular phase and(HCP + BCC) duplex-structured Mg–Li alloys has been summarized and reviewed, and the future trend about the studies on corrosion behavior of Mg–Li-based alloys and possible solving methods for the improvement in corrosion resistance are discussed also.

关键词： Magnesium–lithium alloys Crystallographic structure Corrosion behavior Corrosion product film Corrosion mechanism

Effects of a variety of cutting fluids administered using the minimum quantity lubrication method on the surface grinding process for nickel-based alloys

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2017年第9期18卷 728-740页

作者： Ryszard WOJCIK Krzysztof NADOLNY Instimte of Machine Tools and Production Engineering Lodz University of Technology Stefanowskiego 1/15 90-924 Lodz Poland Department of Production Engineering Koszalin University of Technology Raclawicka 15-17 75-620 Koszalin Poland

This paper presents the characteristics of nickel-based alloys, alongside their division into groups, and describes thefeatures that make such materials difficult to grind. The possibilities of exerting a positive influence upon machining conditions,especially through the proper application of grinding fluids, are briefly presented. Both the precise methodologies for, and theresults of, the experimental tests carried out on flat surfaces are also detailed. The aim of these tests was to determine the influenceof the application of two types of grinding liquid （Ecocut Mikro Plus 82 and Biocut 3000） upon the grinding force values andsurface roughness of the machined workpieces made from three nickel alloys （Nickel 201, INCONEL~ alloy 600, and MONEL^alloy 400）. An additional goal of the tests was to determine the influence of grinding wheel structure on the course and results ofthe machining process. The results indicate that the physical and chemical properties of Biocut 3000 enabled the most advanta-geous properties of the machined surface roughness, alongside a simultaneous increase in grinding power, when compared to theresults when applying Ecocut Mikro Plus 82. The results showed an almost inversely proportional dependence upon the specifictangential grinding force Ft＇ and arithmetic mean deviation of the surface profile Ra values, especially in cases of machining Nickel201 and INCONEL alloy 600. The original traverse grinding methodology used in the tests made it possible to assess the changesof the grinding conditions within the conventionally selected zones.

关键词： Nickel-based alloys Surface grinding Minimum quantity lubrication Hard-to-cut materials Grinding force Surface roughness

Design of near-α Ti alloys via a cluster formula approach and their high-temperature oxidation resistance

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Journal of Materials Science & Technology 2019年第6期35卷 1008-1016页

作者： Beibei Jiang Donghui Wen Qing Wang Jinda Che Chuang Dong Peter K. Liaw Fen Xu Lixian Sun Key Laboratory of Materials Modification by Laser Ion and Electron Beams (Ministry of Education) School of Materials Science and Engineering Dalian University of Technology Dalian 116024 China Department of Materials Science and Engineering The University of Tennessee Knoxville Tennessee 37996 USA Guangxi Key Laboratory of Information Materials Guangxi Collaborative Innovation Center of Structure and Property for New Energy and MaterialsSchool of Material Science and Engineering Guilin University of Electronic Technology Guilin 541004 China

The multi-component composition characteristics of high-temperature near-α Ti alloys were investigated in the present work by means of a cluster formula approach. The uniform cluster formula [CN12 cluster](glue atom)3 for the hexagonal close-packed α solid solution was first obtained based on the Friedel oscillation theory, with a total atom number in the formula of Z = 16. Then it was analyzed that the Z values in the cluster composition formulas of typical near-α Ti alloys are within the range of Z = 16.0016.30, being perfectly consistent with the ideal Z = 16. Based on it, a series of new alloys with Z = 16 and with Nb/Ta substitution for Mo in Ti1100 alloy were designed, suction-cast into φ 6 mm rods, and then heat-treated with solid solution and aging. It was found that the alloy with co-addition of Mo, Ta and Nb has a high strength and good ductility at both room and high temperatures. More importantly, the additions of Nb and Ta can contribute to the formation of continuous and compact Al2O3 scales, resulting in an obvious improvement of oxidation resistances at both 923 K and 1073 K. The effects of Mo, Ta and Nb on the oxidation behaviors of the designed alloys at 1073 K were further discussed.

关键词： Near-α Ti alloys Composition design Cluster formula approach Oxidation resistance Mechanical property

Improvement of microstructure and coercivity for Nd-Fe-B sintered magnets by boundary introducing low melting point alloys

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Journal of Rare Earths 2020年第4期38卷 395-401页

作者： Shuai Cao Xiaoqian Bao Jiheng Li Haijun Yu Kunyuan Zhu Xuexu Gao State Key Laboratory for Advanced Metals and Materials University of Science and Technology BeijingBeijing 100083China

Different from the grain boundary diffusion process(GBDP),which is suitable for modifying thin magnet,a green-pressing agents permeation process(GAPP)that uses low melting point alloys was applied to the Nd-Fe-B green compact with a thickness over 15 mm to reconstruct the boundary microstructure of a sintered Nd-Fe-B magnet.The coercivity increases from 12.3 kOe for the sample free of Pr80Al20 to16.8 kOe for the sample with 2 wt%Pr80Al20.By further increasing the Pr80Al20 content to 3 wt%,the coercivity increases slightly,but the remanence and Hk/Hcj deteriorate obviously.The optimal comprehensive properties of Hcj=16.8 kOe,Br=13.4 kG and Hk/Hcj=0.975 are obtained at 2 wt%Pr80Al20,since matrix phase grains are separated by relatively continuous thin grain boundary layers,which weaken the magnetic coupling between adjacent grains.The coercivities of the samples from the GAPP that use2 wt%Pr80Al20,Pr70Al30 and Pr60Tb20Al20 alloys,respectively,can be enhanced to a large extent.However,the coercivity of the magnet reconstructed with Pr80Al20 is lower than that of the sample with Pr60Tb20Al20 but is higher than that of the sample reconstructed with Pr70Cu30 alloy.Moreover,the coercivity of the sample from the GAPP using 2 wt%Pr80Al20 is much higher than that of the sample from the GBDP,which is due to a nearly uniform boundary microstructure from the surface to the interior of the thick magnet from the GAPP,thus providing new insights into the fabrication of thick and bulky permanent magnets with high coercivity.

关键词： Nd-Fe-B sintered magnets Green-pressing agents permeation Grain boundary diffusion Pr-Al alloys Thick and bulky magnets Rare earths

Effects of high-pressure rheo-squeeze casting on the Fe-rich phases and mechanical properties of Al-17Si-(1,1.5)Fe alloys

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International Journal of Minerals,Metallurgy and Materials 2018年第9期25卷 1018-1026页

作者： Chong Lin Shu-sen Wu Shu-lin Lü Ping An He-bao Wu State Key Laboratory of Materials Processing and Die & Mould Technology Huazhong University of Science and Technology Hubei Provincial Key Laboratory of Chemical Equipment Intensification and Intrinsic Safety Wuhan Institute of Technology

The effects of high pressure rheo-squeeze casting(HPRC) on the Fe-rich phases(FRPs) and mechanical properties of Al-17 Si-(1,1.5)Fe alloys were investigated. The alloy melts were first treated by ultrasonic vibration(UV) and then formed by high-pressure squeeze casting(HPSC). The FRPs in the as-cast HPSC Al-17 Si-1 Fe alloys only contained a long, needle-shaped β-Al5 Fe Si phase at 0 MPa. In addition to the β-Al5 Fe Si phase, the HPSC Al-17 Si-1.5 Fe alloy also contained the plate-shaped δ-Al4 Fe Si2 phase. A fine, block-shaped δ-Al4 Fe Si2 phase was formed in the Al-17 Si-1 Fe alloy treated by UV. The size of FRPs decreased with increasing pressure. After UV treatment, solidification under pressure led to further refinement of the FRPs. Considering alloy samples of the same composition, the ultimate tensile strength(UTS) of the HPRC samples was higher than that of the HPSC samples, and the UTS increased with increasing pressure. The UTS of the Al-17 Si-1 Fe alloy formed by HPSC exceeded that of the Al-17 Si-1.5 Fe alloy formed in the same manner under the same pressure. Conversely, the UTS of the Al-17 Si-1 Fe alloy formed by HPRC decreased to a value lower than that of the Al-17 Si-1.5 Fe alloy formed in the same manner.

关键词： high pressure rheo-squeeze casting Al-17Si-(1,1.5)Fe alloys Fe-rich phases mechanical properties

Phase diagrams of permanent magnet alloys: Binary rare earth alloy systems

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Journal of Rare Earths 2019年第10期37卷 1040-1046页

作者： Kaicheng Yang Jiang Wang Qingrong Yao Zhao Lu Maohua Rong Huaiying Zhou Guanghui Rao School of Materials Science and Engineering & Guangxi Key Laboratory of Information Materials Guilin University of Electronic Technology

Thermodynamic optimization of the binary rare earth alloy(Cee La, Cee Pr, Cee Nd and Lae Nd) systems was performed in this work through the CALPHAD method based on the critical evaluation of all available phase diagram and thermodynamic data reported in the literature. During the thermodynamic modeling, the solution phases including liquid, bcc, fcc and dhcp, were treated as the substitutional solution model. Thermodynamic parameters of the stable phases in the Cee La, Cee Pr, Cee Nd and Lae Nd binary systems are obtained finally and would be used directly to develop the thermodynamic database of the multi-component Nde Fee B-based alloys, which is indispensable for designing alloy compositions and processes of Nde Fee B permanent magnets with highly abundant rare earth metals.

关键词： Permanent magnets Rare earth alloys Phase diagrams CALPHAD

Surface and Subsurface Defects Studies of Dental alloys Exposed to Sandblasting

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Acta Metallurgica Sinica(English Letters) 2019年第10期32卷 1181-1194页

作者： Krzysztof Siemek Miroslaw Kulik Marat Eseev Miroslaw Wrobel Andrey Kobets Oleg Orlov Alexey Sidorin Joint Institute for Nuclear Research Joliot-Curie 6 Dubna Moscow Region Russian Federation 141980 Institute of Nuclear Physics PAS E. Radzikowskiego 152 31-342 Krakow Poland Institute of Physics Maria Curie-Sklodowska University pl. M. Curie-Skiodowskiej 1 20-031 Lublin Poland Northern Arctic Federal University Severnaya Dvina Emb. 17 Arkhangelsk Russian Federation 163002 AGH University of Science and Technology 30 Mickiewicza Ave 90-059 Krakow Poland Institute of Electrophysics and Radiation Technologies NAS of Ukraine Chernyshevsky St. 2& Kharkiv 61002 Ukraine

The defects created in commercial dental alloys during blasting with alumina particles propelled in compressed air under pressure 0.1 and 0.4 MPa have been studied using positron annihilation spectroscopy, scanning electron microscopy and X-ray diffraction. It was observed that higher pressure causes the increase in roughness and damaged zone range. The type of defects was determined as vacancies on dislocations. The defect concentration decreases with the depth and depends on alloys' type and applied pressure. The Rutherford backscattering spectroscopy and variable energy positron beam studies indicate shallow alumina deposition in material and show that small pressure of 0.1 MPa is not enough to remove metal surface oxides completely in 60 s in all studied dental alloys.

关键词： Sandblasting Positron annihilation technique Dental alloys Defects analysis Oxides