检索结果-南通市图书馆

THEORETICAL DISCUSSION ON UNSTEADY FLOW OF FLUID DURING METAL ATOMIZATION　

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 1995年第1期8卷 65-71页

作者： Yang Liushuan Yang Gencang zhou yaohe Northwestern Polytechnical Univ Xi'an China

The expressions of fluid velocity under several conditions during gas atomization according to the unsteady flow mechanics are propsed, and the basic ways to maintain the stability of fluid flow is analyzed

关键词： gas atomization liquid unsteady flow powder metallurgy

An intrinsic correlation between driving force and energy barrier upon grain boundary migration

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2018年第8期34卷 1359-1363页

作者： Bo Lin Kang Wang Feng Liu yaohe zhou State Key Laboratory of Solidification Processing Northwestern Polytechnical University

The migration of grain boundary （GB）, which plays a key role in the microstructural evolution of polycrys- talline materials, remains mysterious due to the unknown relationship between GB mobility associated with specific geometry and external conditions （e.g. temperature, stress, etc., hence the thermodynamic driving force）. Combining the rate equation of GB migration with molecular dynamics simulations, an intrinsic correlation between driving force and energy barrier for the migration of various types of GBs （i.e. twist, symmetric tilt, asymmetric tilt, and mixed twist-tilt） is herein explored, showing the decrease of energy barrier with increasing thermodynamic driving force.

关键词： Grain boundary Molecular dynamics Thermodynamics Kinetics

Amorphous Formation in an Undercooled Binary Ni-Si Alloy under Slow Cooling Rate

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2009年第3期25卷 370-372页

作者： Yiping Lu Gencang Yang Xiong Li yaohe zhou State Key Laboratory of Solidification Processing Northwestern Polytechnical University Xilan 710072 China

High undercooling up to 392 K was achieved in eutectic Ni70.2Si29.8 alloy melt by using glass fluxing combined with cyclic superheating. A small quantity of amorphous phase was obtained in bulk eutectic Ni70.2Si29.8 alloy when undercooling exceeds 240 K under slow cooling conditions （about 1 K/s）. The amorphous phase was confirmed by high-resolution transmission electron microscopy and differential scanning calorimetry.

关键词： Eutectic alloy Amorphous phase Rapid solidification

Crystallization Behavior of Zr_(55)Al_(10)Cu_(30)Ni_5 Bulk Metallic Glass Rolled at Room Temperature

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2010年第2期26卷 177-180页

作者： Yong Hu Jinfu Li Pengna Zhang yaohe zhou State Key Laboratory of Metal Matrix Composites School of Materials Science and Engineering Shanghai Jiao Tong University Shanghai200240 China School of Materials Science and Engineering Taiyuan University of Science and Technology Taiyuan 030024 China

Zr55Al10Cu30Ni5 bulk metallic glass was rolled up to 95% in thickness reduction at room temperature, and the dependences of microstructure and thermal stability on the strain were investigated. It is revealed that phase transformations do not occur during the rolling, but the split of the crystallization peaks becomes more and more obvious with increasing thickness reduction. Analyses of the radial distribution functions and the pair correlation functions indicate that the rolling has enhanced the short-range order, which should be responsible for the enlarging split of the crystallization peaks.

关键词： Metallic glass Plastic deformation Microstructure Thermal stability

Directional Solidification Velocity of Undercooled Cu_(70)Ni_(30) Alloy Melt

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2001年第5期17卷 572-574页

作者： Research Notes JinfuLI Xueping ZHANG and yaohe zhou Gencang YANG School of Materials Science and Engineering Shanghai Jiao Tong UniversityShanghai 200030China State Key Laboratory of Solidification Processing Northwestern Polytechnical University

The directional dendrite growth velocity in the Cu70Ni30 alloy melt undercooled by 90-185 K was measured by high speed cinematography, and compared with the calculated free dendrite growth velocity. It is found that at lower undercoolings the interaction between the adjacent directionally growing dendrites is weak, and there is not a marked difference between the velocity of the directionally growing dendrite and that of free dendrite. But with undercooling increasing, the interaction is enhanced due to the decrease of the primary arm spacing, which makes the velocity difference enlarge quickly.

关键词： Directional Solidification Velocity of Undercooled Cu Velocity Alloy Melt

Growth morphology and evolution of quasicrystal in as-solidified Y-rich Mg-Zn-Y ternary alloys

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2007年第5期26卷 435-439页

作者： WAN Diqing YANG Gencang CHEN Sulin ZHU Man zhou yaohe State Key Laboratory of Solidification Processing Northwestern Polytechnical University Xi＇an 710072 China

A petal-like icosahedral quasicrystal with five branches,which is considered to be the representative morphology of the icosahedral quasicrystal,has been observed in the Y-rich Mg-Zn-Y ternary alloys. Moreover,the polygon-like morphology,another pattern of the icosahedral quasicrystal,has also been found in the Y-rich Mg-Zn-Y ternary alloys. The latter morphology results from the evolution of the former one. The growth mechanism of the petal-like morphology of the icosahedral quasicrystal was also discussed. Alloying composition,i.e.,Y element content,is a major factor inducing the morphology evolution of the icosahedral quasicrystal.

关键词： Mg-Zn-Y ternary alloys icosahedral quasicrystal morphology evolution Y element

NUMERICAL SIMULATION OF CHANNEL SEGREGATION IN Al-4.5wt-%Cu ALLOY

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 1991年第8期4卷 108-114页

作者： YU Qiuping zhou yaohe Northwestern Polytechnical University,Xi’an,China Northwestern Polytechnical Univ Xi'an China

Equations for numerical simulation of channel segregation based on a model of continuum ap- proach to porous medium were *** order to solve the non-linear computation prob- lem caused by the interactions between unknown variables in the equations,the trial-and-er- ror method is *** computation results showed that the radial back-flow due to natural convection in mushy zone indeed exists in A1-4.5wt-%Cu alloy ingot under the condition of low cooling rate,and that the numerical simulation of channel segregation is applicable due to the coincidence of calculated concentration with the experimental values.

关键词： channel segregation numerical simulation back-flow mushy zone

Microstructures and Morphology Evolution of Icosahedral Phase of As-cast Mg_(67.4)Zn_(28.9)Y_(3.7) Ternary Alloy Subjected to the Pouring Temperature

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2009年第4期25卷 445-448页

作者： Man Zhu Gencang Yang Diqing Wan Suling Cheng yaohe zhou State Key Laboratory of Solidification Processing Northwestern Polytechnical University Xi＇an 710072 China

The microstructure, chemical composition and morphology evolution of icosahedral quasicrystalline phase of Mg67.4Zn28.9Y3.7 ternary alloy were investigated in detail at different pouring temperatures by X-ray diffraction （XRD）, scanning electron microscopy （SEM） and energy-dispersive spectrum （EDS）. Low interracial energy favors the formation of l-phase. The experimental results show that the primary l-phase reveals petal-shaped with five and six branches, where each branch has facetted growth morphology with the size ranging from 50 to 100μm. As the temperature decreases, the polygon-shaped l-phase forms, attributed to the decomposition of branch of petal-shaped l-phase, and then it grows bigger and some of the fine polygons join together to form large polygons. Besides these, （α-Mg＋l-phase） eutectic structures disappear and the relative amount of Mg7Zn3 phase increases as the pouring temperature decreases. The chemical composition and morphology evolution of l-phase were also discussed.

关键词： Icosahedral quasicrystal Mg-Zn-Y Morphology evolution Eutectic structures

Influence of Al-Ti-B addition on the microstructure and mechanical properties of A356 alloys

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2009年第2期28卷 181-186页

作者： Zhu Man Yang Gencang Yao Lijuan Cheng Suling zhou yaohe NW Polytech Univ State Key Lab Solidificat Proc Xian 710072 Peoples R China

The mechanical properties (σb,σ0.2,and δ) and fracture behavior of tensile specimens of the refined A356 alloys were investigated as a function of the addition level of Al-Ti-B master alloy under both as-cast and T6 heat-treated conditions. The results show that as the addition level of Al-5Ti-1B master alloy increases from 0.1 wt.% to 5.0 wt.%,the mechanical properties of refined A356 alloys improve steadily and then decrease slightly under both as-cast and T6 heat-treated conditions. Also,they display exc...

关键词： Al-Ti-B master alloy mechanical properties fracture behavior aging precipitation phase