L. W Zhang
,
R.S. Wang
,
J. Th.M.De Hosson
,
Y.L. Xia and F. G. Wang 1) The State Key Lab. for Materials Modification by Laser
,
Ion and Electron Beams
,
Dalian University of Technology
,
Dalian 116023
,
China 2) Department of Applied Physics
,
University of Groningen
,
The Netherlands
金属学报(英文版)
A three-dimensional transient heat transfer model for laser transformation hardening process has been developed in this paper. The finite size of the laser treated sample, the surface heat loss of the sample, the latent heat of phase transformation and the temperature dependence of thermal properties of materials were considered. The heat source was considered as a moving Gaussian heat flux with a constant velocity. Three-dimension unequally spatial grid explicit finite difference equations, alternating direction implicit finite difference equations and implicit finite difference equations were deduced respectively. Three programs to calculate the temperature field were developed using Fortran language. The transient temperature fields of C22, 42CrMo, C60 steel samples during laser transformation hardening process were calculated using these programs, and the widths and depths of laser transformation hardening zones were also predicted. C22, 42CrMo, C60 steel samples were treated by CO_2 laser,the widths and depths of laser transformation hardening zones of these samples were also measured experimentally. The calculated widths and depths of laser transformation hardening zones are in good agreement with the experimental results.
关键词:
temperature field
,
null
,
null
Scripta Materialia
The epsilon-Fe2-3N nitrides in the compound layer of ion-nitrided pure iron were studied with transmission electron microscopy. A superlattice with lattice parameters (a" = 2aroot3 = 0.9294 nm, c" = c = 0.4382 run) bigger than those of epsilon hexagonal close packed unit (a = 0.2683 nm, c = 0.4382 nm), which was tentatively named as epsilon" superstructure, was investigated by electron diffraction method. A series of its diffraction patterns were recorded and the diffraction intensity was analyzed. (C) 2002 Acta Materialia Inc. Published by Elsevier Science Ltd. All rights reserved.
关键词:
nitrides;ordering;crystal structure;electron diffraction;transmission electron microscopy;microscopy
XU Huibin TAN Shusong Technische Universitat Berlin
,
FRG XU Huibin Dipl.-Ing
,
FB9
,
Physikalische Ingenieurwissenschaft
,
HF1
,
TU Berlin
,
1000 Berlin 12
,
FRG
金属学报(英文版)
The radiation of material surface by high intensity laser beams is used to produce the uhrafine powder of pure Fe and ZrO_2.The morphology,size and phases of the powder were examined by X-ray diffraetometer,scanning electron microscopy as well as transmission electron microscopy.In pure Fe a considerable quantity of γ-phase was found in the powder.In ZrO_2 powder,instead of stable phase,two metastable phases appeared.
关键词:
laser beam
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null
,
null
Journal of Magnetism and Magnetic Materials
The electron paramagnetic resonance spectrum of the KMgF3:Fe3+ system has been studied on the basis of the complete energy matrices for the electron-electron repulsion, the ligand-field and the spin-orbit coupling of d(5) configuration ion with a trigonal symmetry. A two-layer-ligand model, which includes six F- ions in the first layer and eight next nearest-neighbor K+ ions in the second layer, has been proposed to describe the real ligand-field. By simulating the second-order and fourth-order EPR parameters D and (a - F) simultaneously, a displacement of a K+ ion along C-3-axis towards the Fe3+ ion has been found theoretically, and this displacement will give rise to the distortion of the octahedron constructed by six F- ligand ions in the first layer. Delta Z is used to describe the displacement of a K+ ion along C3-axis towards the Fe3+ ion, and two angles theta(1) and theta(2) between the Fe3+-F- band and C3-axis are taken to describe the local distortion along the [111] direction. By adjusting the Delta Z, the range of the local distortion parameters Delta theta(1) = 5.54 degrees-6.07 degrees, Delta theta(2) = -4.60 degrees to -5.00 degrees are determined, and the EPR spectrum of the KMgF3:Fe3+ system has been satisfactorily explained by the two-layer-ligand model. (c) 2006 Elsevier B.V. All rights reserved.
关键词:
KMgF3 : Fe3+ system;local lattice structure distortion;EPR spectrum;ligand-field theory;superposition-model analysis;spin-hamiltonian parameters;single-crystals;doped kmgf3;field;kznf3;state;fe-3+;laser;mn2+
Physica Status Solidi B-Basic Research
A simple theoretical method is introduced for studying the local molecular structure of the (MnO(6))(10) coordination complex. By diagonalizing the complete energy matrices of the electro-electron repulsion, the ligand field and the spin-orbit coupling for a d(5) configuration ion in a trigonal ligand field, the local distortion structure of the (MnO(6))(10) coordination complex for Mn(2-) ions in A PCC:Mn(2+) (PCC) - {[(CH(3))(2)N](2)OPOPO[N(CH(3))(2)](2)} (ClO(4))(2), A - Mg, Zn) complex systems is investigated. Both the second-order zero field splitting parameters b(2)(0) and the fourth-order zero field splitting parameter b(4)(0) are taken simultaneously in the structural investigation. From electron paramagnetic resonance (EPR) calculations, the local structure parameters R = 2.18 angstrom, theta = 56.38 degrees for Mn(2) ions in Mg PCC Mn(2+) and R = 2.20 angstrom, theta = 56.52 degrees for Mn(2+) complex systems are determined, respectively. It is found that the theoretical calculation results of the BPR spectra for Mn(2+) ions in A PCC:Mn(2+) complex systems are in good agreement with the experimental values. (c) 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
关键词:
single-crystals;epr-spectra;field epr;absorption;state;octamethylpyrophosphoramide;temperature;phase;salts;site
WANG Xiao
,
WANG Zuo-cheng
,
WANG Xie-bin
,
WANG Yi-ran
,
GAO Jun-qing
,
ZHAO Xiu-ling
钢铁研究学报(英文版)
Microstructures and critical phase-transformation temperature of boron-nickel added Nb-treated high strength low alloy (HSLA) H-beams cooled at different cooling rate, with different deformation were investigated. Continuous cooling transformation (CCT) diagram of this new type of steel was obtained by using Gleeble 1500 thermomechanical simulator. Microstructures and hardness, especially micro-hardness of the experimental steel were investigated by optical microscopy (OM), scanning electron microscope (SEM), Rockwell and Vickers hardness tests. Phase analysis was also studied by X-ray diffraction (XRD). The results indicated that with increase of cooling rate, microstructures of continuous cooled specimens gradually transformed from polygonal ferrite and pearlite, grain boundary ferrite and bainite, bainite and martensite to single martensite. The CCT diagram revealed that slow cooling was needed to avoid austenite-bainite transformation to ensure toughness of this steel. By plastic deformation of 40%, austenite-ferrite transformation temperature increased by 46 ℃, due to deformation induced ferrite transformation during continuous cooling, but Rockwell hardness has little change.
关键词:
thermomechanical simulation
,
HSLA H-beam
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microstructure
,
CCT diagram
