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Effect of Al_4C_3 Particle Size Distribution in a Al–2.5C Master Alloy on the Refining Efficiency of the AZ31 Alloy

Acta Metallurgica Sinica(English Letters) 2017年第6期30卷 505-512页

作者： Yu-Zhen Zhao Xiao-Teng Liu Hai Hao Key Laboratory of Solidification Control and Digital Preparation Technology(Liaoning Province) School of Materials Science and EngineeringDalian University of TechnologyDalian 116024China

The Al-2.5C master alloy is prepared to investigate the effect of the Al4C3 particle size distribution on the refining efficiency of the AZ31 alloy. The results indicate that the Al4C3 particles are potent nucleation substrates for primary α-Mg grains. With 1.0 wt% master alloy addition, the grain size is reduced from 204 to 70 μm. The grain refining efficiency of the Al4C3 particles on the AZ31 alloy is calculated to be 0.04%-0.75%. Such low refining efficiency is mainly attributed to the size distribution of the Al4C3 particles. The particle sizes are in the range from 0.18 to 7.08 μm, and their distribution is well fitted by a log-normal function. The optimum particle size range for significant grain refinement is proposed to be around 5.0-7.08 μm in the present conditions.

关键词： Particle size distribution Grain refining efficiency Al-2.5C master alloy Magnesium alloys

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Effect of calcium addition on microstructure, casting fluidity and mechanical properties of Mg-Zn-Ce-Zr magnesium alloy

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Journal of Rare Earths 2017年第5期35卷 503-509页

作者：付玉王晗刘晓滕郝海 Key Laboratory of Solidification Control and Digital Preparation Technology (Liaoning Province) School of Materials Science and Engineering Dalian Uni-versity of Technology Dalian 116024 China

The influence of Ca addition on the as-cast microstructure, casting fluidity and mechanical properties of the Mg-4.2Zn-1.7Ce-0.5Zr（wt.%） alloy was investigated. The results showed that the as-cast alloys consisted of α-Mg matrix, Ca-contained T-phase and Mg51Zn20 phase. Addition of 0.2 wt.%–0.6 wt.% Ca led to effective grain refinement and enhanced the fluidity of the alloys. When the content of Ca was 0.2 wt.%, the alloy exhibited the finest grain size of 35.9 μm, and the filling length was increased by approximately 55.4% compared with the quaternary alloy. The improvement of the fluidity was attributed to the grain refinement, less energy dissipation and the oxidation resistance of Ce and Ca. With an increase in Ca content, the yield strength increased gradually, whereas the ultimate tensile strength and elongation showed a decreasing tendency. Moreover, the fracture surface mode was quasi-cleavage fracture.

关键词： magnesium fluidity refinement ultimate tensile attributed eutectic equiaxed cleavage elongation

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Effect of Niobium on Microstructure and Properties of the CoCrFeNb_xNi High Entropy Alloys

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Journal of Materials Science & technology 2017年第7期33卷 712-717页

作者： Hui Jiang Li Jiang Dongxu Qiao Yiping Lu Tongmin Wang Zhiqiang Cao Tingju Li Key Laboratory of Solidification Control and Digital Preparation Technology （Liaoning Province） School of Materials Science and Engineering Dalian University of Technology Dalian 116024. China

A series of CoCrFeNb_xNi（x values in molar ratio, x = 0, 0.25, 0.45, 0.5, 0.75, 1.0 and 1.2） high entropy alloys（HEAs） was prepared to investigate the alloying effect of Nb on the microstructures and mechanical properties. The results indicate that the prepared CoCrFeNb_xNi（x 〉 0） HEAs consist of a simple FCC solid solution phase and a Laves phase. The microstructures of the alloys change from an initial single-phase FCC solid solution structure（x = 0） to a hypoeutectic microstructure（x = 0.25）, then to a full eutectic microstructure（x = 0.45） and finally to a hypereutectic microstructure（0.5 〈 x 〈 1.2）. The compressive test results show that the Nb0.45（x = 0.45） alloy with a full eutectic microstructure possesses the highest compressive fracture strength of 2558 MPa and a fracture strain of 27.9%. The CoCrFeNi alloy exhibits an excellent compressive ductility, which can reach 50% height reduction without fracture. The Nb0.25 alloy with a hypoeutectic structure exhibits a larger plastic strain of 34.8%. With the increase of Nb content, increased hard/brittle Laves phase leads to a decrease of the plasticity and increases of the Vickers hardness and the wear resistance. The wear mass loss, width and depth of wear scar of the Nb1.2（x = 1.2） alloy with a hypereutectic structure are the lowest among all alloy systems, indicating that the wear resistance of the Nb1.2 alloy is the best one.

关键词： Alloy design Microstructure Mechanical properties Wear resistance

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Composition,Microstructure,Phase Constitution and Fundamental Physicochemical Properties of Low-Melting-Point Multi-Component Eutectic Alloys

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Journal of Materials Science & technology 2017年第2期33卷 131-154页

作者： Kaiyao Zhou Zhongyi Tang Yiping Lu Tongmin Wang Haipeng Wang Tingju Li Key Laboratory of Solidification Control and Digital Preparation Technology (Liaoning Province) School of Materials Science and EngineeringDalian University of Technology Department of Applied Physics Northwestern Polytechnical University

Low-melting-point alloys have an extensive applications in the fields of materials processing, phase change energy storage, electronic and electrical automatic control, continuous casting simulation, welding, etc. Specifically, the eutectic compositions make up a large number of low-melting-point alloys that are ex- ploited because of their desirable features like single melting peaks, excellent operational reliability, and casting fluidity. However, the fundamental physicochemical properties from the current available liter- ature on low-melting-point multi-component eutectic alloys （LMP-MCEAs） are rather rare and lowly accurate, including the exact melting temperatures and compositions, constituent phases, microstruc- tures and morphologies, melting enthalpies, specific heats, densities, and so on. This lack of information seriously limits the development and application of low-melting-point multi-component eutectic alloys. In this paper, the low-melting-point multi-component eutectic alloys composed of Bi, Cd, Sn, Pb, and In elements synthesized by high vacuum induction melting and fundamental data were investigated by scan- ning electron microscopy （SEM）, energy dispersive spectrometry （EDS）, X-ray diffraction （XRD）, differential scanning calorimetry （DSC）, and density analysis instrument. Most of the LMP-MCEAs with complex eu- tectic morphology structures and XRD diffraction patterns could be explained with the fact that they were three-phase eutectic alloys with mixed growth way. Generally, LMP-MCEAs present an extremely low melting point between 48.3 and 124 ℃ and high density between 8 and 10 g/cm3.

关键词： Multicomponent alloys Eutectic alloy Microstructure Physicochemical properties

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Multi-dimensional characterization and controlling of microstructure evolution during solidification of metallic alloys

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IOP Conference Series: Materials Science and Engineering 2019年第1期580卷

作者： Tongmin Wang Key Laboratory of Solidification Control and Digital Preparation Technology (Liaoning Province) School of Material Science and Engineering Dalian University of Technology Dalian 116024 China

Metallic alloys are important structural and functional materials and have been widely applied in industry. The performance of metallic alloys strongly depends on the microstructures after solidification. Many effective methods are introduced to control the microstructure evolution during solidification, including grain refining, adding rare earth (RE) elements, applying electric current and/or magnetic field, etc. However the inherent mechanisms affecting the microstructure formation are still unclear due to the limitation of real time and multidimensional characterization technique. With the development of the third generation synchrotron radiation light source, a real time imaging technology in 2D (two dimensional) or 3D (three dimensional) view with strong penetrability, high spatial and temporal resolution, nondestructive features has been developed to break those limitations. In this paper, some application cases during solidification performed in our group are reported in different alloys and using different solidification controlling techniques. Different solidification behaviors in those cases are revealed and discussed.

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Distribution of Inclusions in 18CrNiMo7-6 Steel Billet and Its Relationship with Inclusion Compositions

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Journal of Physics: Conference Series 2020年第1期1699卷

作者： N. Wang C.F. Fang L. Zhao K. Huang R. Wang J.M. Wang H. Hao Key Laboratory of Solidification Control and Digital Preparation Technology (Liaoning Province) School of Materials Science and Engineering Dalian University of Technology Dalian China Dalian University of Technology Jiangsu Research Institute Co. Ltd Changzhou China Tel: 0086-411-84706114 Anhui Linhong Heavy Industry Technology Co. Ltd. Xuancheng China

The 18CrNiMo7-6 steel billet was prepared by the process of EBT→LF→VD→die casting and forging. The position distribution, composition, type and cause of inclusions in the billet were statistically analysed by ASPEX and scanning electron microscopy. The results show that there are obvious distribution differences of inclusions in different parts of the steel billet. In contrast, the number density of inclusions in the billet corresponding to the ingot riser and the negative segregation zone is higher; the average composition point of the inclusions in the slow cooling zone tends to be distributed in the higher temperature zone of the MgO-Al2O3-CaO ternary phase diagram.

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Grain nucleation and growth behavior of a Sn-Pb alloy affected by direct current： An in situ investigation

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Journal of Materials Science & technology 2017年第10期33卷 1134-1140页

作者： Fenfen Yang Zongning Chen Fei Cao Rong Fan Huijun Kang Wanxia Huang Qingxi Yuan Tiqiao Xiao Yanan Fu Tongmin Wang Key Laboratory of Solidification Control and Digital Preparation Technology (Liaoning Province) School of Materials Science and Engineering Dalian University of Technology Dalian 116024 China School of Chemical Engineering Dalian University of Technology Dalian 116024 China School of Automotive Engineering Dalian University of Technology Dalian 116024 China Beijing Synchrotron Radiation Facility Institute of High Energy Physics Chinese Academy of Sciences Beijing 100049 China Shanghai Synchrotron Radiation Facility Shanghai Institute of Applied Physics Chinese Academy of Sciences Shanghai 201204 China

In situ synchrotron X-ray radiography was used to study the effect of direct current（DC） on the grain nucleation and growth of Sn-50 wt.%Pb alloy. The results showed that applying DC adequately during solidification could effectively enhance the grain nucleation and inhibit its growth. Imaging of comparative experiments with varying DC intensity indicated that the final grain size, determined by the competition between grain nucleation and growth, was sensitively dependent on the DC intensity. It was found that the average grain size was decreased from 1632 to 567 μm with DC density of 1.5 A/mm^2 compared to the case without DC. Beyond this value, raising the current density may cause a significant decrease in the nucleation rate, and thus lead to a coarsening of the grain structure.

关键词： Sn-Pb alloy Synchrotron X-ray radiography solidification Microstructure Electric current

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A PROMISING preparation METHOD FOR AL/7075-B4C/AL LAYERED COMPOSITE BY CONTINUOUS CASTING AND HOT ROLLING

A PROMISING PREPARATION METHOD FOR AL/7075-B4C/AL LAYERED CO...

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第二十一届国际复合材料大会

作者： Yubo Zhang Yingshui Yu Tingju Li Key Laboratory of Solidification Control and Digital Preparation Technology (Liaoning Province) School of Materials Science and Engineering Dalian University of Technology

Layered composite possesses the combinative properties of different materials, such as high strength, high ductility, low density, *** the present work, a three-layered composite material, in which the outer layer is pure Al and the interlayer is 7075-BC with 40 wt.% BC, was obtained by a two-step method consisting of semi-continuous casting and hot rolling *** semicontinuous casting, the uniform distribution of reinforcement BC particles along with a good metallurgical bonding was achieved, with no defects, cavities or segregation at the ***, the hot rolling was carried out at 450 ℃, and the composite plate of 20 mm thickness, including the interlayer of 14 mm, was *** layered composite exhibited evident soft-hard-soft structure with layers of different hardness（165 HV of inner layer and 27.6 HV of outer layer） and satisfactory compression performance.

关键词： Layered composite B4C reinforcement Semi-continuous casting Hot-rolling Mechanical properties

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Microstructure and mechanical properties of Al/7075-B4C/Al composite by continuous casting and hot rolling

Microstructure and mechanical properties of Al/7075-B4C/Al c...

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第二十一届国际复合材料大会

Laminated composite possesses the combinative properties of different materials,such as high strength, high ductility, low density, etc..In the present work, a three-layer composite material was obtained by a two-step method of direct chill（DC）casting and hot-rolling process, in which the outer layer is pure Al and the interlayer is 7075-BC with 40 wt.% BC *** the DC casting, uniform distribution of reinforcement BC particles along with a good metallurgical bonding was achieved,without defect, cavities or segregation near the ***, the hot rolling was carried out at 450℃, the composite plate was obtained with a thickness of 20 mm,including the interlayer of 14 *** laminated composite exhibited evident soft-hard-soft structure with layers of different hardness（165 HV of inner layer and 27.6 HV of outer layer） and satisfactory performance of shock resistance and tensile property.

关键词： Laminated composite B4C particles Direct chill casting Hot-rolling Mechanical properties

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MICROSTRUCTURAL AND DRY SLIDING WEAR BEHAVIOR OF TIB2 REINFORCED COPPER MATRIX COMPOSITE FABRICATED BY IN SITU CASTING PROCESS

MICROSTRUCTURAL AND DRY SLIDING WEAR BEHAVIOR OF TIB2 REINFO...

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第二十一届国际复合材料大会

作者： Cunlei Zou Huijun Kang Zongning Chen Wei Wang Rengeng Li Tongmin Wang Key Laboratory of Solidification Control and Digital Preparation Technology (Liaoning Province) School of Material Science and Engineering Dalian University of Technology

Particulate reinforced copper matrix composites TiB particles reinforced copper matrix composites were fabricated by traditional casting from in-situ synthesized between Cu-B and Cu-Ti master *** microstructure and mechanical properties of the composites with different content of TiB and loading wear condition on the tribological behavior of Cu/TiB composites were *** results show that TiB particles are in situ formed in the copper matrix and the TEM images show the well bonding between copper and *** the increasing amount of in-situ TiB particles in copper matrix, the tensile strength and hardness are significantly improved, but the elongation and electrical conductivity slightly *** friction and wear characteristics of the composites have been determined by carrying out dry sliding tests on pin-ondisk machine under different loads, speed and *** volume loss rate of the composites under different condition shows the significant improvement of wear property with the addition of TiB particles in copper matrix.

关键词： In situ copper matrix composite Microstructure Wear Mechanical properties

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