M.D. Starostenkov
,
E. V.Kozlov
,
O. V. Andruhova
,
N. V. Lomskikh
,
N.M. Gurova and A. V. Borissov 1) General Physics Department
,
ASTU
,
Lenin St. 46
,
Barnaul
,
656099
,
Russia 2) Physics Department
,
TSABU
,
Solyanaya Sq.
,
2
,
Tomsk
,
634003
,
Russia
金属学报(英文版)
The kinetics of internal boundaries relaxation: antiphase domain boundaries and interphase boundaries-in the conditions of high-temperature annealing and the structure transformations are investigated in homophase and heterophase systems. Homophase systems look like ordered binary alloy and include antiphase domain boundaries of various orientation. Clear components border on ordered alloy in heterophase systems and two processes take place simultaneously here-disordering of binary alloy and solution in ordered phase of clear component. Computer experiment is realized in the sphere of temperatures close to the temperature of order-disorder phase transition in the limits of two-dimensional model of atom diffusion at the vacant knots of crystal lattics.
关键词:
computer simulation
,
null
,
null
,
null
,
null
Acta Chimica Sinica
Passive film formed on 304 stainless steel in 2.5 mol/L H2SO4 solution by using alternating voltage (A. V.) passivation have been investigated by measuring capacitance and photoelectrochemical parameters. The investigation of the effect of measure frequency on the slope of Mott-Schottky curve has been carried out. The photoelectrochemical measurements were consistent with the capacitance measurement. Analysis of the experimental results showed that the passive film formed 304 stainless steel by using A. V. passivation exhibits semiconducting properties. Using the simple model of semiconductor rather than the multi-donor level model can explain satisfactorily the semiconducting behavior of the film formed on 304 stainless steel by using A.V. passivation.
关键词:
A. V. passivation;passive film;semiconducting properties;stainless;steel;model;electrodes
QIAO Lijie LIU Rui XIAO Jimei University of Science and Technology Beijing
,
Beijing
,
China
金属学报(英文版)
The effects of stress components on nucleation sites and propagation directions of stress cor- rosion cracks in brass were investigated with specimens under mode Ⅱ and mode Ⅲ loadings. The results indicated that under mode Ⅱ loading,stress corrosion cracks nucleated on the site with maximum normal stress component and propagated along the plane perpendieular to the maximum normal stress,under mode Ⅲ loading,the stress corrosion crack was not evident on the 45°plane due to the general corrosion in aqueous solution with high NH_4OH concentra- tion,while stress corroded in aqueous solution with low NH_4OH concentration, numerous cracks with spacings of 10—150μm were found on the 45°plane with maximum normal stress and no stress corrosion cracks was observed on the plane with maximum shear stress.
关键词:
stress corrosion cracking
,
null
,
null
,
null
Journal of Physical Chemistry A
The density functional method with relativistic effective core potential has been employed to investigate systematically the geometrical structures, relative stabilities, growth-pattern behaviors, and electronic properties of small bimetallic M(2)Au(n) (M = Ag, Cu; n = 1-10) and pure gold Au(n) (n <= 12) clusters. The optimized geometries reveal that M(2) substituted Au(n+2) clusters and one Au atom capped M(2)Au(n-1) structures are dominant growth patterns of the stable alloyed M(2)Au(n) clusters. The calculated averaged atomic binding energies, fragmentation energies, and the second-order difference of energies as a function of the cluster size exhibit a pronounced even odd alternation phenomenon. The analytic results exhibit that the planar structure Ag(2)Au(4) and Cu(2)Au(2) isomers are the most stable geometries of Ag(2)Au(n) and Cu(2)Au(n) clusters, respectively. In addition, the HOMO-LUMO gaps, charge transfers, chemical hardnesses and polarizabilities have been analyzed and compared further.
关键词:
effective core potentials;transition-metal atoms;density-functional;theory;photoelectron-spectroscopy;molecular calculations;silver;clusters;fluorescence spectroscopy;polarizability;anions;adsorption
常秀丽
,
王永欣
,
陈铮
,
张静
,
程立维
稀有金属材料与工程
基于微观相场模型,研究了Ni64Al21V15合金在1150 K时效过程中相结构演化.结合微观组织演化图像和各个格点上原子占位几率的演化,分析了DO22结构向L10 (M=1)结构转变机制.合金沉淀中期,在相界处析出L10(M=1)结构.研究发现,L10 (M=1)结构形成可分为3类:在DO22与L12相界处形核,沿[001]方向排列,向DO22相扩张;在DO22结构90°有序畴界处形核,沿[001]方向排列,向DO22扩张;在2个[100]向排列的DO22结构交界处形核,沿[100]方向排列,向DO22结构扩张.DO22相中,V主要占据β位,Ni主要占据α2和α3位,Al主要占据α1位;随后,V向α2位跃迁,在(002)面富聚且发生有序化,逐渐占据β和α2位,Ni原子发生面间跃迁,由α2位跃迁至α1位,逐渐占据α1和α3位,Al原子向相外扩散.DO22结构最终转变为高度有序的L10(M=1)结构.
关键词:
结构转变
,
L10(M=1)结构
,
序参数
,
Ni-Al-V合金
,
微观相场
Journal of Molecular Modeling
The density functional theory (DFT) method has been employed to systematically investigate the geometrical structures, relative stabilities, and electronic and magnetic properties of Au (n) M (M = Al and Si, n = 1-9) clusters for clarifying the effect of Al (Si) modulation on the gold nanostructures. Of all the clusters studied, the most stable configurations adopt a three-dimensional structure for Au (n) Al at n = 4-8 and Au (n) Si at n = 3-9, while for pure gold systems, no three-dimensional lowest energy structures are obtained. Through a careful analysis of the fragmentation energy, second-order difference of energy, HOMO-LUMO energy gap, and magnetic moment as a function of cluster size, an odd-even alternative phenomenon has been observed. The results show that the clusters with even-number valence electrons have a higher relative stability, but lower magnetic moments. Furthermore, Al (Si) doping is found to enhance the stabilities of gold frameworks. In addition, the charge analysis has been given to understand the different effects of individual doped atom on electronic properties and compared further.
关键词:
Cluster;Density functional theory;Electronic property;Geometric;configuration;Relative stability;nanoclusters;spectroscopy;geometries;oxidation;energies;cations;silver;co
Applied Physics Letters
We have succeeded in synthesizing PrFe11V1-xTix (x=0.2-1) compound and their nitrides with the ThMn12-type structure. The phase formation and magnetic properties have been investigated by x-ray diffraction, differential thermometric analysis, and magnetic measurement. The stable temperature range of the 1-12 phase for PrFe11V1-xTix alloys has been determined as a function of Ti content. PrFe11V compounds with the ThMn12-type structure do not exist and PrFe11Ti compounds with the TnMn(12)-type structure are obtained by annealing in a narrow temperature range between 1303 and 1383 K. Furthermore, 1-12 phase with the ThMn12-type structure can be obtained at lower temperature and wider temperature range with decreasing Ti content x (0.2 less than or equal to x less than or equal to 1). PrFe11V1-xTixNy with x=0.2-1 has a T-c of about 730-785 K, B-a larger than 8 T and M-s in the range 144-148 emu/g. These intrinsic magnetic properties are highly favorable for permanent magnet applications. As a preliminary, an intrinsic coercivity of 5.4 kOe is obtained for PrFe11V0.5Ti0.5Ny at room temperature by using mechanical alloying technique. (C) 1997 American Institute of Physics.
关键词:
