材料期刊网

Microstructure of Laser Processed T10 Carbon Tool Steel

Xianzhang BU Fine Mech.Mater.and Technol.Dept. , Changchun Institute of Optics and Fine Mechanics , Changchun , 130022 , ChinaHongying WANG Zhang LI Jiandong HU Microanalysis Center , Jilin University of Technology , Changchun , 130025 , China

材料科学技术（英）

The microstructure of the laser melted 1.0%C tool steel have been investigated.The region affected by the laser can be subdivided into 3 zones,which consist of a melted region at the surface,a zone with solid state transformation and the area adjacent to the unaffected substrate where cementite is slightly dissolved.The melted zone possessed a cellular growth morphology consisting of austenite and martensite.The carbon content of the austenite was measured to be over 1 wt-%.A great deal of retained austenite and twinned martensite were found in the first two zones(the melted and solid transformed).

关键词: laser process , null , null

Investigation of the local structure of the tetragonal Ni2+-V-Li center in LiCl:Ni2+ crystal from epr parameters

Radiation Effects and Defects in Solids

The zero-field splitting D and the g factor g(parallel to), Delta g (= g(parallel to) - g(perpendicular to)) of the tetragonal Ni2+-V-Li center in LiCl:Ni2+ crystal have been studied from the high-order perturbation formulas of these EPR parameters for d(8) ions in tetragonal symmetry. On the basis of this, the local structure of this tetragonal center is determined and the negative sign of the zero-field splitting D of the crystal is obtained.

关键词: electron paramagnetic resonance;local structure;crystal-field theory;Ni2+;LiCl;spin-hamiltonian parameters;superposition-model;ni(ii) compounds;ground-state;ions;symmetry;halides;cr3+

Two-step magnetization in a spin-chain system on the triangular lattice: Wang-Landau simulation

Physical Review B

The Wang-Landau algorithm is used to study the thermodynamic and magnetic properties of triangular spin-chain system based on two-dimensional Ising model in order to understand the magnetic-order dynamics in Ca(3)Co(2)O(6) compound. The calculated results demonstrate that the equilibrium state of the rigid spins produces the two-step magnetization curve at low temperature even when the random-exchange term is considered. This work indicates that the four-step magnetization behavior observed experimentally must be due to the nonequilibrium magnetization.

关键词: calcium compounds;exchange interactions (electron);Ising model;magnetisation;thermodynamics;one-dimensional ca3co2o6;density-of-states;compound ca3co2o6;phase-diagram;proteins;crystal

116HU聚酯亚胺无挥发浸渍树脂的性能及其在风电上的模拟结构试验

王君 , 邹家桂 , 陈政标 , 高建武 , 刘彦坤 , 张杰元 , 宋莎

绝缘材料

　　为解决苯乙烯和甲基苯乙烯在VPI浸渍树脂应用于风力发电机中的不足，采用不饱和聚酯亚胺、引发剂和无挥发活性稀释剂研制出116HU聚酯亚胺无挥发浸渍树脂，并对其各项性能进行了研究。结果表明：116HU聚酯亚胺无挥发浸渍树脂的常规性能满足风力发电机的要求，其耐热等级可达H级。用该树脂浸渍的风电模拟线棒具有优异的介电性能、耐湿热交变和高低温循环冲击性能及耐盐雾性能等，能满足风力发电机在极端环境运行的要求。

关键词: 聚酯亚胺 , 无挥发 , VPI , 风力发电机 , 耐湿热 , 耐盐雾

Atom location by channeling enhanced microanalysis study of site distributions of alloying elements in titanium aluminides

Journal of Materials Research

The original equation of Spence and Tafto for quantitative determination of site occupancy using atom location by channeling enhanced microanalysis method has been extended to take into account both delocalization effect and the influence of point defects (antisite atomic distribution and vacancies). The outcome of this treatment suggests that, for crystals free of antisite defects, the accuracy of site occupancy is influenced by delocalization effect but is independent of both thermal and structural vacancies. For crystals free of structural vacancies, the accuracy of site occupancy is influenced by both delocalization effect and antisite defects, but is independent of thermal vacancies. The delocalization effect was shown to vary with channeling strength at a given channeling condition. For a binary ordered phase in which at least one of the host elements exhibits weak delocalization effect las is the case for many transition-metal aluminides), a tangent-line method for obtaining the value of k (a parameter necessary for the calculation of site occupancy) was proposed, allowing the determination of the delocalization correction factor for the other host element. Application of this method to estimating the delocalization effect of Al in Ti3Al and TiAl under axial and planar channeling conditions, respectively, was demonstrated.

关键词: general formulation;electron-diffraction;x alloys;alchemi;occupancies;ti3al;additions

Jian ZHANG/Langhong Lou

材料科学技术（英）

关键词:

Spin Hamiltonian parameters and defect structure for the X-ray-induced NbLi4+ center in LiNbO3 crystal

Journal of Alloys and Compounds

The spin Hamiltonian (SH) parameters (g factors g(x), g(y), g(z) and hyperfine structure constants A(x), A(y), A(z)) of the low-symmetry Nb-Li(4+) antisite defect center in the X-ray-irradiated congruent undoped LiNbO3 crystal are calculated from the high-order perturbation formulas of SH parameters for d(1) ions. The calculated results are in reasonable agreement with the experimental values. Some information related to the defect structure of the Nb-Li(4+) center (characterized mainly by the Nb-Li(4+) displacement Delta z from the ideal Li+ site along C-3 axis and the displacement Delta x of O2- ions in the oxygen triangle between Nb-Li(4+) and Nb-Nb(5+)) is obtained from the calculations. These displacements are consistent with the expectation based on the electrostatic interaction and electron cloud overlap. The results are discussed. (C) 2006 Elsevier B.V. All rights reserved.

关键词: ferroelectrics;inorganic compounds;crystal and ligand fields;point;defect;electron paramagnetic resonance (EPR);temperature-dependence;lithium-niobate;epr parameters;cr3+ centers;endor;ions;ruby

Theoretical studies of the EPR parameters and the local structure of the tetragonal Fe+ center in KTaO3

Zeitschrift Fur Naturforschung Section a-a Journal of Physical Sciences

The EPR parameters (zero-field splitting D and g factors g(parallel to) and g(perpendicular to)) and the local structure for the tetragonal Fe+ center in KTaO3 are theoretically studied by using the perturbation formulas of the EPR parameters for a 3d(7) ion in tetragonally distorted dodecahedra. Based on these studies, we find that the impurity Fe+ may not locate on the regular dodecahedral K+ site but suffer a large off-center displacement Delta Z (approximate to 0.43 angstrom) along one of the < 100 > (or C-4) axes, which is responsible for the large tetragonal distortion of the impurity center. The displacement Delta Z obtained in this work is comparable with that (approximate to 0.46 angstrom) of a similar monovalent Li+ on K+ site of KTaO3 obtained from the nuclear quadrupole shift and can be regarded as reasonable. The calculated g factors, particularly the anisotropy Delta g (= g(perpendicular to) - g(parallel to)) based on the above displacement, agree with the observed values.

关键词: defect structures;electron paramagnetic resonance (EPR);crystal- and;ligand-fields;Fe+;KTaO3;electron-paramagnetic-resonance;atomic screening constants;nominally;pure ktao3;scf functions;dipole glass;ions;impurities;scattering;crystal;sites

Theoretical studies of EPR spectra and defect structure for Er(3+) center in lithium niobate

Spectrochimica Acta Part a-Molecular and Biomolecular Spectroscopy

The optical and EPR spectra of octahedral Er(3+) center in LiNbO(3) have been studied by diagonalizing 364 x 364 complete energy matrices. The new set of crystal-field parameters that can well account for the Stark levels and EPR parameters have been obtained for Er(3+) ions in LiNbO(3). Simultaneously, by simulating the most reliable six-order parameter B(60) obtained, we have presented the evidence that the Er(3+) ions do not occupy the actual Li(+) site, but have a displacement along the C(3)-axis away from the Li(+) center by about 0.0454 nm. The conclusion is well in accord with that drawn by earlier workers. (c) 2010 Elsevier B.V. All rights reserved.

关键词: EPR parameters;Defect structure;Complete energy matrices;linbo3 single-crystals;wave-guide lasers;24 degrees c;superposition;model;local-structure;ions;sites;spectroscopy;diffraction;fields

Ion sputter erosion in metallic glass-A response to "Comment on: Homogeneity of Zr(64.13)Cu(15.75)Ni(10.12)Al(10) bulk metallic glass" by L-Y. Chen, Y-W. Zeng, Q-P. Cao, B-J. Park, Y-M. Chen, K. Hono, U. Vainio, Z-L. Zhang, U. Kaiser, X-D. Wang, and J-Z Jiang J. Mater. Res. 24, 3116 (2009)

Journal of Materials Research

The morphology of the dark and bright regions observed by transmission electron microscopy for the Zr(64.13)Cu(15.75)Ni(10.12)Al(10) bulk metallic glass strongly depends on the ion beam parameters used for ion milling. This indicates that the ion beam could introduce surface fluctuation to metallic glasses during ion milling.

关键词: room-temperature