材料期刊网

Pitting Corrosion Behaviour of Monel-400 Alloy in Chloride Solutions

V.K.Gouda , I.Z.Selim , A.A.Khedr , A.M.Fathi

材料科学技术（英文）

Pitting corrosion behavior of Monel-400 alloy in 3.5 wt pct NaCl sodium chloride solution has been investigated using the cyclic potentiodynamic anodic polarization technique. The effects of chloride ion concentration, pH values and different temperatures on the pitting parameters were determined. The morphology of the pits produced after anodic polarization treatments were inspected by scanning electron microscope (SEM). The results indicated that, the increase in chloride ion concentration shifts Epit and Eprot of the alloy toward negative values and the pitting potential is much more dependent on pH value in the basic region. The breakdown of passivity with increasing temperature may be due to kinetic changes of passivating films and dissolution rate of the alloy in its passive state.

关键词:

Phase relations in the ZnO-V(2)O(5)-K(2)O system

Chinese Physics B

The subsolidus phase relations of a ZnO-V(2)O(5)-K(2)O system are investigated by X-ray powder diffraction. There is 1 ternary compound, 11 binary compounds and 14 three-phase regions in this system. The phase diagrams of V(2)O(5)-K(2)O with the K(2)O content ranging from 0 to 71 mol% and pseudo-binary system of ZnO-K(2)ZnV(2)O(7) are also studied by X-ray powder diffraction and differential thermal analysis methods.

关键词: ZnO-V(2)O(5)-K(2)O system;ZnO-K(2)ZnV(2)O(7) system;V(2)O(5)-K(2)O;system;X-ray diffraction;crystal-structure;magnetic-properties;v2o5-zno system;potassium;trivanadates;diffraction;refinement;diagram;oxides;znv2o6

K-RE变质处理改善Fe-V-W-Mo合金性能的研究

符寒光 , 李定 , 邢建东

稀有金属材料与工程

研究了K-RE变质处理对Fe-V-W-Mo合金机械性能和热物理性能的影响.结果发现,Fe-V-W-Mo合金经K-RE变质处理后,硬度和红硬性略有增加,冲击韧性提高41.82%,达到11.09J/cm2,耐磨性和导热系数提高,热膨胀系数减小.分析了K-RE改善Fe-V-W-Mo合金性能的机理,并制造了K-RE变质Fe-V-W-Mo合金轧辊,在热轧生产中使用获得了良好的效果.

关键词: K-RE变质处理 , Fe-V-W-Mo合金 , 机械性能 , 物理性能 , 轧辊

K-RE变质处理改善Fe-V-W-Mo合金组织

符寒光 , 邢建东 , 李言祥

稀有金属材料与工程

用K-RE对Fe-5%V-5%W-5%Mo-5%Cr-3%Nb-2%Co-2%C合金变质处理,使凝固组织发生了明显的变化,不仅碳化物和基体组织明显细化,还出现共晶碳化物断网现象,产生了较多的小块状和颗粒状碳化物.经K-RE变质处理Fe-V-W-Mo合金加热温度950℃时,碳化物断网明显,加热温度1 000℃时,多数碳化物已断网,并出现了数量较多的颗粒状碳化物,加热温度1 050℃时,碳化物网状组织全部消失,大部分碳化物变成了球状组织.

关键词: 变质处理 , K-RE , Fe-V-W-Mo合金 , 共晶碳化物 , 团球化

Local structural parameters of the tetragonal V2+-V-M centers in MCl : V2+ (M = Na, K, Rb) crystals estimated from EPR data

Physica Status Solidi B-Basic Research

The high-order perturbation formulas of zero-field splitting D and gyromagnetic factors g(parallel to) and g(perpendicular to) for 3d(3) ions in tetragonal symmetry are established by using a two-spin-orbit(SO)-parameter model where the contributions to these EPR parameters from both the SO coupling of the central 3d(3) ions and that of the ligands are considered. From these formulas, the local structural parameters for the tetragonal V2+-V-M centers in MCl:V2+ (M = Na, K, Rb) crystals are estimated from the EPR data. The results are compared with those obtained from the conventional one-SO-parameter model where only the contribution of the SO coupling of central 3d(3) ions is included. The reasonableness of the results based on the two-SO-parameter model is discussed.

关键词: ions

Phase relations in the Fe-rich region of the Nd-Fe-V system at 1323 K

Journal of Alloys and Compounds

Phase relations in the Fe-rich region of the Nd-Fe-V system at 1323 K have been investigated by means of powder X-ray diffraction. In the investigated composition region, two ternary phases: Nd(Fe1-xVx)(12) (x=0.125-0.167) and Nd-3(Fe1-xVx)(29) (x=0.066-0.095), and one pseudobinary phase: Nd-2(Fe1-xVx)(17) (x=0.000-0.067) are identified. The dependence of the cell parameters on x in Nd(Fe1-xVx)(12), Nd-3(Fe1-xVx)(29) and Nd-2(Fe1-xVx)(17) are presented. Also given are the dependences of the Curie temperatures on the V content (x) in Nd(Fe1-xVx)(12) and Nd-2(Fe1-xVx)(17) The preferential occupation of V in Nd(Fe1-xVx)(12) and Nd-2 (Fe1-xVx)(17) is deduced from the slope of a and c with V content. (C) 1999 Published by Elsevier Science S.A.

关键词: ternary neodymium compounds;Nd-Fe-V compounds;crystal structure;solid;solubilities;phase equilibria;neutron-diffraction;magnetic-properties

V-M(M=Li,Na,K,Sc,Ag)二元系的相图热力学研究

胡标 , 尹明 , 王庆平 , 闵凡飞 , 杜勇

兵器材料科学与工程

基于文献报道的实验数据,采用相图计算(CALPHAD:CALculation of PHAse Diagrams)方法对V-M(M=Li,Na,K,Sc,Ag)5个二元系进行相图热力学研究.通过热力学优化计算获得了一套描述液相、(V)、(Li)、(Na)、(K)、(αSc)、(βSc)和(Ag)相的热力学参数.V-Li、V-Na和V-K体系中的气相视为由组元V、Li、Li2、Na、Na2、K和K2混合的理想气体.与实验相图数据对比表明,获得的热力学参数能够准确地描述实验相平衡数据.

关键词: V-M(M=Li,Na,K,Sc,Ag) , CALPHAD方法 , 相图 , 热力学模型

一种改进的C-V方法对向列相液晶弹性常数k11、k33测量的理论研究

孔祥建 , 荆海 , 黄霞 , 廖燕平 , 刘金娥

液晶与显示 doi:10.3969/j.issn.1007-2780.2007.05.017

提出了一种更为准确的测量向列相液晶展曲、弯曲弹性常数的C-V方法.以正性液晶材料为例,当沿面排列的液晶分子预倾角不为零时,阈值电压值不易确定, k11的确定必定存在误差,而以前报道并未考虑到此问题.文章针对此问题给出了在强锚定条件下,预倾角不为零时C-V的关系式,并提出了通过曲线拟合来同时确定弹性常数k11、k33的方法.此方法对弹性常数的测量更为准确,液晶盒的制作要求降低,且测试简单、易操作.

关键词: 向列相液晶 , 电容-电压 , 弹性常数 , 预倾角 , 曲线拟合

Investigations of the electron paramagnetic resonance g factors Er3+-V-K for the trigonal ErK centers in KMF3 (M = Mg and Zn)

Journal of Magnetism and Magnetic Materials

The electron paramagnetic resonance g factors g(parallel to) and g(perpendicular to) for the trigonal Er3+-V-K centers (where V-K denotes K+ vacancy) in KMF3 (M = Mg and Zn) are theoretically investigated from the perturbation formulas of the g factors for a 4f(11) ion in trigonal symmetry. In these formulas, the contributions to the g factors from the second-order perturbation terms and the admixture of various energy levels are taken into account. In the above trigonal centers, the impurity Er3+ resides in the octahedral M2+ site of both crystals, associated with one V-K in the C-3-axis due to charge compensation. By analyzing their g factors, we find that the impurity Er3+ in both centers would move towards the V-K by an amount DeltaZ along the C-3-axis due to electrostatic attraction. The calculated g factors for the Er3+ centers based on the above displacements DeltaZ show good agreement with the observed values. The validity of the results is discussed. (C) 2004 Elsevier B.V. All rights reserved.

关键词: electron paramagnetic resonance (EPR);defects and impurities;crystal-field and spin hamiltonians;Er3+;KMF3;(M = Mg and Zn);crystal-field;superposition-model;perovskite kmgf3;conversion;parameters;fluorides;kznf3

X70管线钢J1d和K1a与V型缺口Ak关系研究

朱杰武 , 柳永宁 , 许雁 , 冯耀荣

机械工程材料 doi:10.3969/j.issn.1000-3738.2005.06.007

在不同温度下测试了X70管线钢动态断裂韧度K1d、J1d和止裂韧度K1a以及夏氏V型缺口冲击韧度Ak,对三者的关系进行了分析.结果表明:温度和加载速率都对断裂韧度产生影响;加载速率变化引起的韧-脆断裂转变具有热激活特征,在热激活分析基础上,在应力强度因子速率K=15 MPa·m1/2s-1条件下,得出断裂韧度、止裂韧度和冲击韧度三者的关系:Ak=4.84×106T-2.8K1d(或K1a).可以用小试样Ak数据计算得到K1d和K1a.

关键词: 管线钢 , 断裂韧度 , 止裂韧度 , 韧-脆断裂转变