X.Sun
,
Z.J.Ding
,
H.M.Li
,
K.Salma
,
Z.M.Zhang
,
W.S.Tan
金属学报(英文版)
A Monte Carlo model considering the electron spin direction and spin asymmetry has been developed. The energy distribution of the secondary electron polarization and the primary energy dependence of the polarization from Fe are studied. The simulation results show that: (1) the intensity of the spin-up secondary electrons is larger thanvthat of thevspin-down secondary electrons, suggesting the secondary electrons are spin polarized; (2) the spin polarization of secondary electrons with nearly zero kinetic energy is higher than the average valance spin polarization, Pb=27 0.000000or Fe. With increasing kinetic energy, the spin polarization of the secondary electrons decreases to the value of Pu remaining constant at higher kinetic energies; (3) the spin polarization increases with an increase in the primary energy and reaches a saturation value at higher primary energy in both the Monte Carlo simulation and experimental results.
关键词:
spin polarization
,
null
,
null
K.Salma
,
Z.J.Ding
,
H.M.Li
,
Z.M.Zhang
金属学报(英文版)
The investigation of influence of surface effects on the energy spectra of electrons is essential for comprehensive understanding of electron-solid interactions as well as quantitative analysis. The accuracy of the analysis depends on the models for elastic and inelastic interactions. Electrons impinging on a solid or escaping from it suffer losses in the surface layer. The energy loss spectra therefore have contributions from surface excitations. The role of surface excitations is characterized by surface excitation parameter (SEP), which indicates the number of surface plasmons created by an electron crossing the surface. The imaginary part of complex self-energy of an electron is related to the energy.' loss cross section. SEP is numerically computed using self-energy formalism and compared with the results as described and calculated by different workers.
关键词:
surface plasmons
,
null
,
null
Z.J.Ding
,
K.Salma
,
Z.M.Zhang
金属学报(英文版)
The full energy distribution of backscattered electrons from the elastic peak down to the true-secondaty electron peak for heavy metals, Ta, W, Pt and Au, in Auger electron spectroscopy in the EN(E) mode has been studied with a Monte Carlo simulation method, which includes cascade-secondary-electron production. The simulation model is based on the use of a dielectric function for describing inelastic scattering and secondary excitation, and on the use of Mott cross sections for elastic scattering. A systematic comparison between the calculated and experimental spectra measured with a cylindrical mirror analyzer has been made for primary energies ranging from 1 to 5keV. Excellent agreement was obtained for these heavy metals on the backscattering background at primary energies in the keV region. A significant contribution of cascade secondary electrons to the measured spectra on the low-energy side was found.
关键词:
backscattered electrons
,
null
,
null
刘永
,
宋耀祖
工程热物理学报
本文采用M-Z干涉测量的方法,研究了半三角形翼片纵向涡发生器强化换热方案对矩形通道内气体流动换热的影响,获得了安装纵向涡发生器前后对流换热温度场的M-Z干涉图像.通过对实验获得的干涉图像进行分析处理,表明安装纵向涡发生器后,通道内入口段流动的热边界层明显变薄,反映了纵向涡对流动换热的强化作用,验证了将M-Z干涉测量方法应用于纵向涡强化换热研究的可行性.
关键词:
纵向涡
,
强化换热
,
M-Z干涉
,
热边界层
陆永浩
,
陈子瑞
,
朱晓锋
材料科学与工艺
为了研究敏化处理对Z3CN20-09M不锈钢高温水应力腐蚀行为的影响，使用敏化处理的Z3CN20-09M不锈钢制成U弯试样，并置于250、290及320℃的高温水中进行应力腐蚀开裂实验，采用扫描电镜观察了高温水实验后试样的氧化膜厚度以及应力腐蚀裂纹的萌生及扩展行为。结果表明：敏化处理增加了氧化膜的厚度，降低了耐蚀能力，使SCC敏感性增大；温度较高时，敏化处理的影响较大；铁素体相容易被侵蚀，大多数点蚀坑产生于铁素体中；SCC裂纹优先在点蚀坑底部和奥氏体/铁素体相界位置处形成；相界面对SCC裂纹的影响取决于SCC裂纹相对于相界面的取向，SCC裂纹扩展方向平行于相界面时裂纹易沿着相界扩展，SCC裂纹扩展垂直于相界面方向时相界面对裂纹扩展起阻碍作用。
关键词:
Z3CN20-09M
,
敏化处理
,
SCC裂纹
,
萌生和扩展
,
相界面
王玮
,
罗奎林
,
陆永浩
材料研究学报
用光学显微镜和扫描电镜等手段研究了核级不锈钢Z3CN20-09M焊缝组织特征,用原位拉伸和EBSD等方法研究了焊缝组织对裂纹扩展的影响.结果表明,焊缝区主要由板条状组织和岛状组织构成.不同的组织对裂纹扩展的阻力不同,岛状组织对裂纹的扩展具有阻碍作用且使裂纹发生偏转,而板条状组织对裂纹扩展无阻碍作用,裂纹可在片层组织中迅速通过.
关键词:
金属材料
,
核级不锈钢
,
焊缝
,
组织裂纹
朱晓锋
,
陆永浩
,
杨海波
材料科学与工艺
为研究国产核级主管道不锈钢Z3CN20-09M中奥氏体/铁素体相界面在裂纹萌生与扩展过程中的作用,通过扫描电镜原位拉伸技术对核级主管道不锈钢在拉伸过程中的组织形变、微裂纹的萌生与扩展进行原位观察,对断口进行了分析.研究表明,在拉伸过程中,微裂纹优先在杂质颗粒和相界位置萌生.当铁素体/奥氏体界面垂直于拉伸方向时,裂纹倾向于沿相界萌生,并沿相界扩展;当铁素体/奥氏体界面平行于拉伸方向时,微裂纹在相界开裂,并垂直于界面扩展,主裂纹发生偏折,界面在裂纹扩展过程中起阻碍作用.
关键词:
核级不锈钢
,
原位拉伸
,
奥氏体/马氏体相界
,
裂纹萌生与扩展
王永强
,
韩军
,
杨滨
,
武焕春
,
王西涛
金属学报
doi:10.3724/SP.J.1037.2012.00730
研究了压水堆核电站一回路主管道用Z3CN20.09M铸造奥氏体不锈钢中金属间相的析出行为.利用Image-pro Plus 6.0软件统计了时效处理后不锈钢中析出金属间相的数量,获得了金属间相的时间-温度-转变(TTT)曲线.结果显示,Z3CN20.09M中析出的金属间相为M23C6和σ相,析出温度范围分别为600-900℃和600-840℃,其中750℃时析出最快.研究表明,M23C6首先在α/γ相界析出,然后σ相在铁素体相内形成.M2aC6和σ相在Z3CN20.09M中固溶化的温度分别为900和850℃.850℃时,M23C6相的析出量随时间延长先增多后减少.
关键词:
Z3CN20.09M不锈钢
,
M23C6
,
σ相
,
析出行为
陈耿
,
谢建良
,
黄鹏
功能材料
采用陶瓷工艺制备C02Z(Ba3(Co0.4Zn0.6)2Fe23.4O41)和BaM(BaFi1.4Co1.4Fe9.2O19)六角铁氧体,二次球磨时掺杂少量BST(BaSrTiO3)铁电材料,对比研究了BST掺杂对Z型和M型铁氧体在1MHz～1GHz频率范围内相对复磁导率(μr=μr1-iμr")的影响.BST的掺杂使Z型铁氧体μr增大,共振频率点移向低频;使M型铁氧体的μr减小,共振频率点移向高频.通过对其微观结构和磁参数的测试分析,讨论了BST掺杂对Z型和M型铁氧体复磁导率不同影响的作用机理.
关键词:
Z型六角铁氧体
,
M型六角铁氧体
,
磁晶各向异性场
,
相对复磁导率
