材料期刊网

氧杂质致Ti-Si-N薄膜高硬度损失的机理

马大衍 , 马胜利 , 徐可为 , 薛其坤 , S. Veprek

材料研究学报 doi:10.3321/j.issn:1005-3093.2008.03.012

基于纳米复合Ti-Si-N薄膜硬度对界面相微结构及微尺度变化极为敏感的实验事实,定量表征了薄膜的硬度与氧杂质含量的关系.结果表明,与高纯度薄膜40-55 GPa高硬度比较,1%-1.5%的氧杂质含量导致薄膜的硬度下降到30 GPa左右.根据纳米晶界面原子模型和实验结果,氧杂质与纳米尺度界面交互作用所引发的微尺度缺陷是硬度下降的诱因,晶界面的氧杂质密度是薄膜高硬度损失程度的决定因素,单个纳米晶周围的氧杂质覆盖度达到10个原子以上时,薄膜的硬度只能达到30 GPa.

关键词: 材料科学基础学科 , 纳米复合薄膜 , 硬度 , 氧杂质

评Veprek的nc-TiN/a-Si3N4模型和其"超过金刚石硬度"的实验基础

李戈扬

无机材料学报 doi:10.15541/jim20140313

由于报道获得了超过金刚石的硬度,TiN/Si3N4纳米复合薄膜成为十多年来超硬材料和薄膜材料的重要热点.本文从实验基础方面对这类薄膜的Veprek模型和"超高硬度"进行了评述.在微结构方面,Veprek提出的非晶Si3N4包裹TiN纳米晶的结构模型(即nc-TiN/a-Si3N4)缺乏足够的实验依据,直接观察表明:高硬度薄膜中的TiN晶粒并非等轴晶,而是纳米直径的柱状晶.就Si3N4界面相来说也并非以1个单分子层(～0.3 nm)的非晶态存在,而是厚度约3个分子层(～0.7 nm)的晶体态,更重要的是Si3N4界面相与相邻的TiN晶体形成了共格结构.在制备技术方面,十余年来始终没有人在这类材料中重复出Veprek超过金刚石硬度的结果,Veprek不仅将其归咎于缺乏足够高的沉积温度和氮分压,甚至归咎于薄膜中存在不可避免的微量氧,但也缺乏足够的直接证据.在超高硬度的样品方面,Veprek所报道超过金刚石硬度(最高达138.9GPa)的样品不但未经任何他人检测确认,而且现在这些样品已经不存在了.

关键词: TiN/Si3N4薄膜 , 超高硬度 , 微结构

FORMATION OF AMORPHOUS GE-S SEMICONDUCTOR ALLOYS BY MECHANICAL ALLOYING

Applied Physics Letters

Amorphous Ge1-xSx(x=0.61, 0.67, and 0.72) semiconductor alloys have been found formed by ball milling of powder mixtures of elemental Ge and S. The amorphization process and the ball-milled products have been investigated by x-ray diffraction, transmission electron microscopy, and Raman scattering. The results show that amorphous Ge-S alloys may form in a self-heating reaction, driven by the large heat of formation of amorphous and/or liquid Ge-S alloys. The structure of mechanically alloyed amorphous Ge-S alloys is similar to but not exactly identical with that of rapidly cooled amorphous Ge-S alloys. The amorphization transition mechanism reported is believed to be suitable for preparing other amorphous semiconductor alloys with similar thermodynamic conditions.

关键词: magnetic-properties;ni-zr;amorphization;powders;transition;interdiffusion;germanium;systems;glasses;metals

VIM法中采用CaO坩埚对Ni基高温合金脱S的影响

牛建平 , 杨克努 , 管恒荣 , 胡壮麒

机械工程材料 doi:10.3969/j.issn.1000-3738.2002.02.002

研究了使用CaO坩埚在VIM法精炼Ni基高温合金过程中S的变化规律及加Al对脱S的影响.试验表明:当CaO坩埚中的含S量高于液态金属中的含S量时,坩埚中的S将进入金属液中而使液态金属增S.加入0.5%的Al经30min精炼后可以使液态金属中的S含量从30mg/kg降低至小于5mg/kg.对CaO坩埚内壁的XRD及成分分析表明,加Al脱S是由于在CaO坩埚壁和金属液间形成低熔点的具有很强脱S能力的3CaO@Al2O3渣.

关键词: VIM , CaO坩埚 , Ni基高温合金 , 脱S

Thermodynamic Behaviour of Fe-S-RE,Fe-Csat.-S-RE,Ni-S-RE,Cu-S-RE Solutions

Ting DU Longmei WANG Yeming WU Yuqing ZHANG Aisheng LIU Central Iron and Steel Research Institute , Beijing , 100081 , China

材料科学技术（英文）

The temperature dependences of the equilibrium constants for the reactions RES_((S))=[RE]+[S]. (RE=Ce,La,Nd,Sm,Y),of the standard Gibbs energies for the RES formed and of the interaction coefficients between RE elements and S for the Fe-base,Ni-base and Cu-base solutions are sum- marized.

关键词: thermodynamics , null , null , null , null

Corrosion behaviour of carbon steel in different concentrations of HCl solutions containing H(2)S at 90 degrees C

Corrosion Science

The corrosion behavior of SAE-1020 carbon steel in H(2)S-containing solutions with different concentration of HCl at 90 degrees C was investigated by weight loss, electrochemical measurements, SEM and XRD analysis. The results showed that the corrosion rate of carbon steel increased with increasing HCl concentration. Uniform corrosion was found on the carbon steel surface in H(2)S + HCl solutions, while corrosion cavities were observed in the solution only containing H(2)S. The ratio of Faradaic process of total corrosion process increased with the increase of HCl concentration. The corrosion products were solely composed of mackinawite in the H(2)S-containing solutions with or without HCl. (c) 2011 Elsevier Ltd. All rights reserved.

关键词: Steel;Weight loss;EIS;SEM;XRD;Acid corrosion;acidic chloride solutions;hydrogen-sulfide;aqueous-solution;iron;sulfides;electrochemical-behavior;media;dissolution;impedance;polarization;environments

Quantum transport of Au-S-S-Au nanoscale junctions

Applied Physics Letters

Transport in S(2) molecules sandwiched between Au electrodes is investigated with a combination of density functional theory and the non-equilibrium Green's function method. We consider four different configurations and find that their conductances are related to the details of the bonding geometry. When S(2) connects to pyramidal-shaped electrodes at the top site, the transmission is governed by a resonance and is strongly affected by the bias. In contrast, the transport of the remaining three configurations is through several closely spaced broad molecular orbitals, and the transmission coefficient is almost flat around the Fermi level. (C) 2012 American Institute of Physics. [doi:10.1063/1.3665614]

关键词: conductance;molecule

恒位移加载条件下X65管线钢H2S应力腐蚀研究

孙新阁 , 霍立兴 , 张玉凤

腐蚀学报（英文）

采用楔形张开加载恒位移实验研究了X65管线钢在H2S溶液中的应力腐蚀开裂行为，并得出了X65管线钢母材、焊缝和热影响区的临界应力强度因子KISCC分别为55.7093 MPa•m 1/2、33.3189 MPa•m1/2和38.0711 MPa•m1/2；平台处的裂纹扩展速率da/dt分别为3.38×10－9m/s、3.5×10－9 m/s和3.5×10－9m/s.研究结果还表明，焊缝比母材具有更高的应力腐蚀敏感性. 

关键词: 管线钢 , null , null

恒位移加载条件下X65管线钢H2S应力腐蚀研究

孙新阁 , 霍立兴 , 张玉凤

腐蚀学报（英文） doi:10.3969/j.issn.1002-6495.2006.03.004

采用楔形张开加载恒位移实验研究了X65管线钢在H2S溶液中的应力腐蚀开裂行为,并得出了X65管线钢母材、焊缝和热影响区的临界应力强度因子KISCC分别为55.7093 MPa·m1/2、33.3189 MPa·m1/2和38.0711 MPa·m1/2;平台处的裂纹扩展速率da/dt分别为3.38×10-9m/s、3.5×10-9m/s和3.5×10-9m/s.研究结果还表明,焊缝比母材具有更高的应力腐蚀敏感性.

关键词: 管线钢 , 临界应力强度因子 , 裂纹扩展速率

EQUILIBRIUM OF Mg-S IN Ni MELTS

WANG Conghua HAN Qiyong University of Science and Technology Beijing , Beijing , China WANG Conghua Faculty of Physical Chemistry of Metallurgy , University of Science and Technology Beijing , Beijing , China

金属学报(英文版)

The equilibrium of Mg-S in Ni melt was studied by the method of vapour equilibrium in a sealed chamber.At 1530℃ the equilibrium constant of the reaction MgS_(s)=Mg_(Ni)+S_(Ni)and the activity interaction coefficient were determined as K_(MgS)=6.76×10~(-5)and e_S~(Mg)=-9.1.

关键词: Equilibrium constant , null , null , null , null