材料期刊网

SYNTHESIS OF INTERMETALLICS BY MECHANICAL ALLOYING

F. H.(Sam) Froes , C. Suryanarayana , and D. Mukhopadhyay (Institute for Materials and Advanced Processes (IMAP) , University of Idaho , Moscow , ID 83844-3026 , USA)C-G. Li(BlM , P.O. Box 81 , Beijing , 100095 , P.R. CHINA)K. Brand(On leave from Institut fur Werkstoffwissenshaft , Technische Universitst Dresden , 07062 Dresden , Germany , at IMAP)

金属学报(英文版)

Mechanical alloying (MA), a solid-state powder processing method, is a "far from equilibrium" synthesis technique which allows development of novel crystal structures and microstructures, leading to enhanced physical and mechanical properties. The ability to synthesize a variety of alloy phases including supersaturated solid solutions, nanocrystalline structures, amorphous phases and intermetallic compounds themselves is discussed. No extension of solubility using MA has been observed in the intermetallics studied. Nanostructured grains were observed in all compositions. Long time milling generally resulted in amorphous phase formation in large part because of the increase in grain boundary energy/mole with reduced grain size; good agreement with the Miedema model for amorphization was obtained in the Al-Fe system. Generally an anneal was required to form the intermetallic after MA; however,intermetallics with a large negative enthalpy of formation were detected in the MA condition. A study of the hot isostatic pressing of γ-TiAl powders produced by MA demonstrated that full density can be achieved at least 400℃ below the normal temperature required for conventional powder, that is 725℃ or below. Nanometered sized grains (≤100nm)were observed after HIP'ing up to 850℃.

关键词: : Intermetallics , null , null

a-C:F:H薄膜的化学键结构

肖剑荣 , 徐慧 , 李幼真 , 刘雄飞 , 马松山 , 简献忠

中国有色金属学报

使用CF4和CH4为源气体,利用射频等离子体增强化学气相沉积法,制备了a-C:F:H薄膜样品.采用拉曼光谱仪、傅里叶变换红外光谱仪、X射线光电子能谱仪(XPS)对薄膜的结构进行了测试和分析.研究发现:该膜呈空间网状结构,膜内碳与氟、氢的结合主要以sp3形式存在,而sp2形式的含量相对较少;在薄膜内主要含有C-Fx(x=1,2,3)、C-C、C-H2、C-H3等以及不饱和C=C化学键;同时,薄膜中C-C-F键的含量比C-C-F2键的含量要高.在不同功率下沉积的薄膜,其化学键结构明显不同.

关键词: a-C:F:H薄膜 , 等离子体增强化学气相沉积 , 低介电常数 , 化学键

马普协会煤化所和F. Schüth教授的研究活动

陆安慧

新型炭材料 doi:10.3969/j.issn.1007-8827.2003.04.014

关键词:

NaCl晶体中氧族离子稳定的(F+2)H心

林碧洲 , 许承晃 , 吴季怀 , 邱继晨

人工晶体学报 doi:10.3969/j.issn.1000-985X.1998.01.022

描述了掺氧族离子(O2-,S2-,Se2-)NaCl晶体中(F+2)H心的制备过程,报道了氧族离子稳定的(F+2)H心的吸收光谱和发射光谱,测量了这些(F+2)H心的室温避光稳定性.研究表明,氧族离子对F+2心的稳定作用顺序为O2-＜Se2-＜S2-,而受这三种离子扰动的(F+2)H心的光谱峰位相对于纯F+2心的移动大小亦为这一顺序.这一顺序与它们相应元素的电子亲合能顺序相同(分别为1.47,2.02,2.07eV).从而,纠正了根据离子大小为预测的结果O2-＜S2-＜Se2-.本文结果对(F+2)H色心激光晶体材料的研究具有指导意义.研究还表明,随着离子半经的增大,生长出优质的掺杂晶体越来越困难.

关键词: 色心激光 , 激活心 , 掺杂效应 , 稳定性

Theoretical calculations of the spin-Hamiltonian parameters for the tetragonal Dy(3+) center in H(f)SiO(4) crystal

Physica B-Condensed Matter

The spin-Hamiltonian parameters (g factors g(parallel to), g(perpendicular to) and hyperfine structure constants (161)A(parallel to), (161)A(perpendicular to), (163)A(parallel to), (163)A(perpendicular to)) for Dy(3+) at the tetragonal H(f)(4+) site of H(f)SiO(4) crystal are calculated from the diagonalization (of energy matrix) method. In the method, we add the Zeeman (or magnetic) and hyperfine interaction terms to the conventional Hamiltonian used in the calculations of crystal-field energy levels. The 66 X 66 energy matrix concerning the new Hamiltonian is established by considering the ground multiplet (6)H(15/2) and the first to fifth excited multiplets (6)H(J) (where J=13/2, 11/2,9/2, 7/2 and 5/2), and the crystal-field parameters in the energy matrix are calculated from the superposition model. From the calculations, the spin-Hamiltonian parameters of H(f)SiO(4):Dy(3+) are explained reasonably and the signs of hyperfine structure constants for (161)Dy(3+) and (161)Dy(3+) isotopes in H(f)SiO(4) are suggested. The results are discussed. (C) 2010 Elsevier B.V. All rights reserved.

关键词: Electron paramagnetic resonance;Crystal-field theory;Point defect;Dy(3+);H(f)SiO(4);superposition-model analysis;single-crystals;paramagnetic-resonance;structure silicates;zircon;growth;hafnon;field;epr;er3

SAM AND XPS STUDIES ON SURFACE SEGREGATION OF SUBSTRATE ELEMENTS IN Au-Ni-KOVAR ALLOY SYSTEM

QI Yunxin TANG Wentai XIA Jianguo Nei Mongol Institute of Metallic Materials , Baotou , ChinaLI Wang ZHAN Zhenzong Institute of Physical and Chemical Engineering Research , Tianjin , China

金属学报(英文版)

The surface segregation of substrate elements through the Au layer in the Au-Ni-Kovar sys- tem specimens heated at 250—350℃ for 0.5—1.5 h has been studied by SAM and XPS. Visual evidence of the mechanism for Ni and Co surface segregation of the complicated sys- tem has been given,i.e.Ni and Co penetrated the gold layer mainly by grain boundary diffu- sion and then covered the Au layer by surface diffusion.The strdy results of the chemical states of surface segregation elements not only indicate that oxygen adsorption and oxidation reaction are the driving force for the surface segregation of Ni and Co,but also show that the above segregation can result in water absorption on surfaces.

关键词: Au-Ni-Kovar alloy system , null , null , null , null

Au-Ni-Kovar合金系统基底元素表面偏聚的SAM和XPS研究

齐芸馨 , 唐文泰 , 夏建国 , 李望 , 展振宗

金属学报

本文采用SAM和XPS对实用Au-Ni-Kovar合金系统热处理样品(250—350℃,0.5—1.5h)进行了基底元素穿透Au层的表面偏聚研究,给出了这一复杂系统中Ni,Co表面偏聚机理的直观证据,即Ni,Co主要是通过晶界扩散穿透Au层而后以表面扩散覆盖镀Au表面的;表面偏聚元素化学态的研究则不仅表明,氧的吸附和氧化反应是Ni,Co表面偏聚的驱动力,而且发现,上述偏聚会引起样品表面吸水的现象。

关键词: Au-Ni-Kovar合金系统 , surface segregation , substrate element , SAM , XPS

H2 SO4-NH4 F-SbF3粗锑电解精炼体系研究

崔焱 , 林艳 , 谢刚 , 杨大锦

黄金 doi:10.11792/hj20140412

采用循环伏安法和线性扫描技术等电化学研究方法，系统研究了电解液体系中各阴阳离子对锑电沉积过程的影响。通过测定Sb3＋、NH4＋、F-、SO2-4及草酸等组分不同质量浓度下体系的循环伏安曲线、稳态极化曲线及塔菲尔曲线，分析了各离子在电解过程中的电化学行为及作用，确定了H2 SO4-NH4 F-SbF3电解液体系合适的成分为Sb3＋90～120 g／L、NH4＋50 g／L、F-80 g／L、H2 SO4360 g／L、H2 C2 O44～10 g／L。在此电解液体系下进行了粗锑的电解精炼试验，阴极锑纯度为99．9436％，达到国标1号精锑标准，阴极电流效率为97．60％。

关键词: 锑 , 电解精炼 , H2 SO4 -NH4 F-SbF3体系

微波ECR-CVD法制备a-C:F:H膜的红外吸收及其光学带隙

甘肇强 , 陆新华

材料科学与工程学报 doi:10.3969/j.issn.1673-2812.2002.02.004

改变CHF3/CH4流量比R=[CHF3]/([CHF3]+[CH4]),采用微波电子回旋共振等离子体化学气相沉积(MWECR-CVD)方法沉积a-C:F:H薄膜.a-C:F:H薄膜的结构和光学带隙使用傅立叶变换红外光谱和紫外-可见光谱来表征.红外结果表明,在低流量比R(R<64%)下,薄膜的红外特征结构主要以-CF(1060cm-1),-CF2(1120cm-1)以及-CHx(2800～3000cm-1)的伸缩振动为主;在高流量比R(R＞64%)下,薄膜表现为类聚四氟乙烯(PTFE)的结构特征,典型的红外特征峰是位于1220cm-1处的-CF2反对称伸缩振动.薄膜的光学带隙Eg随流量比R的变化表现为先降后升.进一步研究表明,薄膜中的H和F浓度调制着薄膜的 C==C共轭双键结构,使光学带隙Eg从2.37到3.3之间变化.

关键词: a-C:F:H薄膜 , 傅立叶变换红外光谱 , 紫外可见光谱

Study of Carbon-poor Regions of Austenite during Bainitic Incubation Period by SAM

Xiaolei WU , Husheng JIA , Xiyan ZHANG and Mokuang KANG(Dept. of Materials Science & Engineering , Northwestern Polytechnical University , Xi'an , 710072 , China)(To whom correspondence should be addressed)

材料科学技术（英文）

The variation of carbon composition in undercooled austenite during bainitic incubation period has been investigated in 40CrMnSiMoVA by scanning auger microprobe (SAM). The results show that the outstanding diffusion and redistribution of carbon occur in isothermally reacted specimens. This leads to the formation of carbon-poor regions (CPR) near austenite grain boundaries and in austenite grains. The carbon content in CPR exceeds the equilibrium carbon composition of ferrite. Furthermore, it is indicated that the existence of CPR is thermodynamically possible.

关键词: