VM.Kuznetsov
,
R.I.Kadyrov and G.E.Rudenskii (Institute of Strength Physics and Material Science
,
Russian Academy of Sciences
,
Siberian Branch.Academicheskii av. 2/1
,
634048 Tomsk
,
Russia)
材料科学技术(英文)
The surface energy values of (100), (110), (111) surfaces in Ni. Al and ordered alloys NiAl and Ni3Al have been calculated within the framework of methodology based upon the electron density functional method. The results of calculations are in good agreement with the known for pure metals experimental data and in case of Ni3Al allop There is also a good agreement with the results obtained by calculation using the embedded atom method. The investigation has been carried out in this work to show that the surface energy σ of alloys can not be interpreted as an averaged concentration σ of pure metals. For NiAl, the obtained resulsts reveal considerable distinctions in anisotropy of a in comparison to the anisotropy of surface energy in pure matals.
关键词:
谢英柏
,
孙刚磊
,
宗露香
,
刘迎福
工程热物理学报
天然气驱动VM循环热泵采用天然气作为高品位驱动能源,无工质替代问题,对缓解夏季电力供应紧张和环境污染等问题具有重要的意义.本文建立了热力学模型,分析结果表明:对于理想循环,热泵性能系数随着高温热源和低温热源温度的升高而增大,随着中间温度热源温度的升高而减小,并且热源温度变化对性能系数的影响从大到小依次为低温热源、中间温度热源和高温热源;对于理论循环,在运行区间,随着转速的增加,制冷量增大,而性能系数降低,但制冷量和性能系数都随着平均压力的增加而增大.
关键词:
天然气驱动
,
VM循环
,
热泵
,
热力学分析
,
性能系数
魏斌
,
严密林
,
白真权
,
冯耀荣
腐蚀学报(英文)
采用电化学方法研究了在模拟罗家寨气田地层水中镍基合金Inconel718和抗硫管材VM80 SS之间的电偶腐蚀特征和电偶效应.结果表明,Inconel 718和VM80 SS的自腐蚀电位分别为-260 mV和-770 mV,当阴阳极面积比S=0.25,1,4,8时,电偶电位Eg处于-760 mV~-700 mV之间,随S增大,Eg正移,Ig/Aa的初始值、稳态值和平均值均增大;而Ig/Ac的初始值降低,稳态值变化不大.根据混合电位理论计算的VM80SS的电偶腐蚀效应γ随S增大而增大,γ=1.14~4.82.
关键词:
电偶腐蚀
,
null
,
null
魏斌
,
严密林
,
白真权
,
冯耀荣
腐蚀学报(英文)
doi:10.3969/j.issn.1002-6495.2007.05.003
采用电化学方法研究了在模拟罗家寨气田地层水中镍基合金Inconel 718和抗硫管材VM80 SS之间的电偶腐蚀特征和电偶效应.结果表明,Inconel 718和VM80 SS的自腐蚀电位分别为-260 mV和-770 mV,当阴阳极面积比S=0.25,1,4,8时,电偶电位Eg处于-760 mV~-700 mV之间,随S增大,Eg正移,Ig/Aa的初始值、稳态值和平均值均增大;而Ig/Ac的初始值降低,稳态值变化不大.根据混合电位理论计算的VM80SS的电偶腐蚀效应γ随S增大而增大,γ=1.14~4.82.
关键词:
电偶腐蚀
,
气田地层水
,
镍基合金Inconel 718
,
抗硫管材VM80 SS
WANG Yandong
,
A. Vadon and J.J. Heizmann(LMPC/ISGMP
,
Universite de Metz
,
F-57045 Metz CEDEX 01
,
France)ZUO Liang(Department of Materials Science and Engineering
,
Northeastern University
,
Shenyang 110006
,
China)Manuscript received 16 November 1995
,
in revised form 15 April 1995
金属学报(英文版)
The texture vectors, as the fundatnental elements of the vector method (VM), are usually determined by the Durand's iterative method. In present paper, the texture vector is derived by two kinds of the maximum entropy method (MEM), which choose pole figure data (MEM(I)) and the series coefficients of pole figures (MEM(II)), respectively, as a constrained condition. The detailed comparisons, including the texture vector and residual vector in the pole figure and ODF, among the results obtained by different methods are given through the ideal fiber texture simulation with Gaussian distribution. It is demonstrated that, although both methods the good results in the ideal texture simulation, the solution on assumption of maximum entropy displays more attractive results. In order to compare the sensitivity of the different methods to the experimental errors, the stochastical errors in pole figures are introduced by the computer random processes (Monte-Carlo simulation). The Monte-Carlo simulation shows that the MEM with the series coefficients as a constrained condition is rather sensitive to the "experimental" errors, however, inversely the conventional VM and MEM with pole figure data as a constrained condition.
关键词:
: texture vector; vector method; maximum entropy method;Monte-Carlo simulation; Gaussian distribution
A.Fallahi
材料科学技术(英文)
The purpose of this research is to quantify the effects of compositional and processing parameters on the microstructure and properties of dual phase steel produced directly by hot rolling and rapid cooling.Steels with the base composition of 0.1%C, 1.4%Si, and 1.0%Mn with additions of 0.5%Cr to influence hardenability, 0.04%Nb to retard recrystallization in the latter stages of rolling, or 0.02%Ti to inhibit grain growth during and after reheating were investigated. Investigation was made to predict microstructure evolution and to correlate microstructure with processing parameters. The effects of the important microstructure parameters such as ferrite grain size, martensite volume fraction (VM) and morphology (polygonal or fibrous) on the tensile and impact properties are discussed. Multiple linear regression analysis of the ultimate tensile strength has shown that, increasing VM and martensite microhardness and grain refinement of ferrite are the major contributions to increase the strength of the steel. It was found that the dual-phase steel produced by controlled rolling process, with a microstructure which consisted of fine grained ferrite (4 mm) and 35%´40% fibrous martensite, presented optimum tensile and impact properties because of enhanced resistance to crack propagation.
关键词:
Dual-phase steel
,
null
,
null
Acta Materialia
Polycrystalline Ni of two purities (99.967% (4N) and 99.5% (2N)) was deformed to an ultra-high strain of epsilon(vM) = 100 (epsilon(vM), von Mises strain) by high pressure torsion at room temperature. The 4N and 2N samples at this strain are nanostructured with an average boundary spacing of similar to 100 nm, a high density of dislocations and a large fraction of high angle boundaries (> 15 degrees) of 0.68-0.74, as determined by transmission electron microscopy, and 0.8-0.83, as determined by electron backscattering diffraction. The deformed samples were annealed isochronally for 1 h at temperatures from 100 to 600 degrees C, and the evolution of the structural parameters (boundary spacing, average boundary misorientation angle and the fraction of high angle boundaries), crystallographic texture and hardness were determined. Based on microstructural parameters the energy stored in the deformed state was estimated to be 14 MPa and 24 MPa for 4N Ni and 2N Ni, respectively. The isochronal annealing leads to a drop in hardness in three stages: a relatively small decrease at low temperatures (recovery), followed by a rapid decrease at intermediate temperatures (recrystallization) and a slow decrease at high temperature (grain growth). Both recovery and recrystallization of the 2N Ni are strongly retarded by the presence of impurities reducing the mobility of boundaries. In the recrystallization stage, changes in hardness, microstructure and texture show that the 4N Ni recrystallizes discontinuously, in spite of a large fraction of high angle boundaries in the deformed state. This finding contradicts previous experiments and theory, which suggest that recrystallization is continuous when the fraction of high angle boundaries is high. In the 2N Ni, the observations suggest that some structural coarsening (continuous recrystallization) may take place simultaneously with discontinuous recrystallization. The findings emphasize the importance of alloying, which can delay the process of recovery and recrystallization and thereby enable tailoring of the microstructure and properties through an optimized annealing treatment. (c) 2009 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
关键词:
Discontinuous recrystallization;Continuous recrystallization;Nickel;Stored energy;Plastic deformation;plastic-deformation;stored energy;aluminum;recrystallization;nickel;microstructure;texture;metals;stability;boundary
安宇龙
,
刘光
,
侯国梁
,
陈建敏
,
赵晓琴
材料导报
采用大气等离子喷涂制备莫来石涂层,对涂层进行了热震试验.以OLYCIA m3图像分析软件测定涂层孔隙率,以MH-5-VM型显微硬度仪测定涂层硬度,依照ASTMC633-79标准测定涂层结合强度,以X射线衍射(XRD)和扫描电镜(SEM)表征涂层的相组成和微观形貌.结果表明,莫来石涂层主要由变形颗粒、未熔融粉末及少量孔隙组成,涂层中没有微观裂纹;涂层中含有莫来石晶体和部分非晶态玻璃相;热震过程中,涂层中的非晶转变为晶态莫来石,同时伴随应力释放,导致涂层出现微观裂纹.
关键词:
大气等离子喷涂
,
莫来石涂层
,
热震试验
,
非晶