S.Q.Wang1
,
2) and H.Q.Ye1) 1) Laboratory of Atomic Imaging of Solids
,
Institute of Metal Research
,
The Chinese Academy of Sciences
,
Shenyang 110015
,
China 2)Department of Materials Science and Metallurgy
,
University of Cambridge
,
Cambridge CB2 3QZ
,
UK
金属学报(英文版)
Apeculiar crystal defect was observed by experiment of high resolution electron microscopy( HREM) .It wasidentifiedtoformed bytwothreading dislocationsand asegmentof(11 20) domain boundary. An atomicstructure model was proposed for the anomalous defect. Theresultofthe weak beam experimentofelectron microscopeaffirmedthesuggested model.Thestructuralpropertiesofseveral GaN(11 2 0) domain boundaries werestudied by Molec ular Dynamicscalculations. Thetheoreticalresultsshowedthatthelike atom bonding domain boundary, whichcomposesthe main partofthe peculiar defect, has much higher formationenergy than itcounterpartof unlike atom bonding domain boundary. Theoutcome providesanotherevidenceforthesuggested model.
关键词:
HREM
,
null
,
null
,
null
,
null
Acta Materialia
The influences of composition and Mn-Ga/Al disordering on the magnetic and elastic properties of the Ni(2)Mn(Al(1-x)Ga(x)) Hensler alloy are investigated by the use of the first-principles exact muffin-tin orbital method in combination with coherent-potential approximation. The transition temperature from the completely disordered B2 phase to the ordered L2(1) phase, estimated by the use of Bragg-Williams-Gorsky approximation, is in excellent agreement with experiments. The site-occupancy in the partially disordered alloy is determined by comparing the free energies of the alloys with different site-occupation configurations. It is found that Mn atoms generally prefer to exchange with Al atoms for the alloy with low degree of disorder and low Ga concentration. With increasing degree of disorder and Ga concentration, Mn may exchange with Ga as well. The total magnetic moment of the completely ordered alloy exhibits a minimum around x = 0.7 due to the competition between the increasing magnetic moments of Mn atoms and the decreasing moments of Ni atoms with increasing x. For the partially disordered alloy, both total and local magnetic moments of Mn and Ni decrease linearly with increasing degree of disorder, and Ga atoms show significant magnetism. The shear moduli C of the alloys are calculated with respect to both x and the degree of disorder. The results show that C decreases with increasing x and degree of disorder. The dependence on composition and on the degree of disorder of the martensitic transition temperatures is discussed in terms of the calculated C. (C) 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
关键词:
Heusler alloy;First-principles calculations;Elastic constants;Martensitic transformation;ni-mn-ga;shape-memory alloys;ni2mnga single-crystals;magnetic-field;heusler alloys;martensitic-transformation;beta-phase;potential model;transition;behavior
赵澎
,
李焰
,
梁强
腐蚀学报（英文）
通过失重实验、电化学测试和扫描电子显微镜研究了无金属酞菁(H2Pc)、酞菁铜(CuPc)和酞菁锌(ZnPc) 在1 mol/L H2SO4中对碳钢的缓蚀作用.结果表明，3种酞菁化合物的缓蚀能力依次为ZnPc > CuPc > H2Pc，其吸附数据均符合Langmuir等温式；它们能同时抑制碳钢在H2SO4中腐蚀的阴极和阳极过程，电化学阻抗谱显示，为变形的单容抗弧，阻抗值随酞菁化合物浓度增加而增加；表面形貌分析也证明了酞菁化合物的加入提高了碳钢的表面完整性，抑制其腐蚀；量子化学计算结果显示，随着分子的最低空轨道(LUMO)的能量升高，酞菁化合物的缓蚀能力降低.
关键词:
酞菁化合物
,
null
,
null
赵澎
,
李焰
,
梁强
腐蚀学报（英文）
doi:10.3969/j.issn.1002-6495.2006.04.001
通过失重实验、电化学测试和扫描电子显微镜研究了无金属酞菁(H2Pc)、酞菁铜(CuPc)和酞菁锌(ZnPc)在1mol/L H2SO4中对碳钢的缓蚀作用.结果表明,3种酞菁化合物的缓蚀能力依次为ZnPc＞CuPc＞H2Pc,其吸附数据均符合Langmuir等温式;它们能同时抑制碳钢在H2SO4中腐蚀的阴极和阳极过程,电化学阻抗谱显示,为变形的单容抗弧,阻抗值随酞菁化合物浓度增加而增加;表面形貌分析也证明了酞菁化合物的加入提高了碳钢的表面完整性,抑制其腐蚀;量子化学计算结果显示,随着分子的最低空轨道(LUMO)的能量升高,酞菁化合物的缓蚀能力降低.
关键词:
酞菁化合物
,
缓蚀剂
,
电化学实验
,
SEM
,
量子化学
刘立甫
,
武会宾
,
王立东
,
刘跃庭
材料热处理学报
采用高温高压反应釜和电化学测试手段对含Cr质量分数为1％的Q125级套管钢焊接接头的CO2腐蚀行为进行了研究.结果表明:焊接接头的母材和热影响区的耐CO2腐蚀性能相近,母材为回火马氏体,热影响区为回火索氏体,组织对实验钢的耐CO2腐蚀性能影响不明显.焊缝区的Cr含量较高,腐蚀产物中的Cr富集加剧,且结构致密,其更能有效的阻止阴离子的通过,从而保护金属基体免受腐蚀介质的腐蚀.电化学分析可得,焊缝区的自腐蚀电位最正,自腐蚀电流最小,不易发生腐蚀;母材区的自腐蚀电位最负,自腐蚀电流最大,母材金属将作为阳极首先发生腐蚀,焊缝作为阴极得到保护.
关键词:
Q125级套管钢
,
焊接接头
,
CO2腐蚀
,
Cr富集
邓秀娟
,
申璐
,
张硕
,
刘月明
催化学报
doi:10.3724/SP.J.1088.2011.10543
系统研究了TS-1/H2O2催化二乙胺(DEA)氧化制备二乙基羟胺(DEHA)的反应规律,考察了DEA氧化及DEHA氧化反应之间的竞争关系.结果表明,H2O2以连续方式进料时,DEA转化率及H2O2有效利用率明显提高,而反应体系中DEA/H2O2的摩尔比对DEHA选择性的影响较大.TS-1既可催化DEA的氧化,又可催化产物DEHA的进一步氧化.
关键词:
钛硅分子筛
,
过氧化氢
,
二乙胺
,
氧化
,
二乙基羟胺
刘晓智
,
刘泉
,
陆世维
催化学报
以具有反应控制相转移特点和可回收再利用的硒为催化剂,以CO/H2O为还原剂,在常压条件下还原1-硝基萘制1-萘胺,考察了不同溶剂和碱对反应的影响. 结果表明,在极性非质子溶剂如二甲基甲酰胺中,以氢氧化钠为助催化剂时1-硝基萘可定量还原为1-萘胺.
关键词:
硒
,
硝基苯
,
还原
,
萘胺
,
一氧化碳
张硕
,
邓秀娟
,
申璐
,
刘月明
催化学报
doi:10.3724/SP.J.1088.2012.11019
将TS- 1/H2O2催化体系用于催化香茅醛氨肟化制备香茅醛肟反应中,结果表明,在优化的反应条件下,香茅醛转化率和香茅醛肟选择性分别达99.9％和99.2％以上.反应过程中主要存在两对竞争反应:TS-1催化的醛肟化反应和碱催化的羟醛缩合反应;TS-1催化的醛肟化反应和双键环氧反应.通过调节体系中氨含量可有效抑制副反应.
关键词:
TS-1分子筛
,
香茅醛
,
过氧化氢
,
氨肟化
,
香茅醛肟
Zhaoyang ZENG
,
Lide ZHANG
,
Xiaohong YAN
材料科学技术（英文）
Ballistic transport of Q1D electrons through multiple magnetic barriers is investigated. It is shown that ballistic conductance peaks disappear progressively with the increase of the oscillation frequency of the confining parabolic potential.
关键词:
卢军辉
,
王晓春
,
刘家琪
,
张成武
,
仇圣桃
,
朴峰云
物理测试
为了考察开发钢Q450NQR1的耐候性,对其分别进行了实验室周期浸润试验和大气暴晒试验,试验结果表明,实验室周期浸润试验中,144h腐蚀率相对Q345B减少了1/3,且Q450NQR1锈层中稳定的α-FeOOH含量较高,而Q345B钢较低;大气暴晒试验中,腐蚀初期Q450NQR1钢试样腐蚀率稍大一些,腐蚀后期,其表面形成稳定的致密锈层后,Q450NQR1钢的耐腐蚀性能开始体现.
关键词:
耐候钢
,
货车车厢
,
X射线衍射
,
大气腐蚀
,
锈层
