L. W. Zhang
,
J. Th.M.De Hosson
,
Y.L. Xia and F. G. Wang 1)The State Key Lab. for Materials Modification by Laser
,
Ion and Beams
,
Dalian University of Technology
,
Dalian 116023
,
China 2)Department of Applied Physics
,
University of Froningen
,
The Netherlands
金属学报(英文版)
In this paper,a thermal elastic-plastic 2-D finite element model of stress generation during laser transformation hardening process was developed. In this model, the mechanical properties of the material, Young's modules E, Poisson's ratio v, yield limit s, and thermal expansion coefficient α, are all change with temperature. The equivalent expansion method was used to deal with the problem with phase transformation. Based on this model, a program to calculate the residual stress field was developed using FORTRAN language. The residual stress fields in CO2 laser transformation hardened MoCu nodular iron were calculated. The calculated results showed that in the transformation hardened zone, the residual stress state is compress,whereas adjacent to this zone the residual stress state is tensile, and there is a tensile stress peak close to the transformation hardened zone. To verify this model, the residual stress fields were measured using X-ray diffraction method. The calculated results of residual stress fields are in good agreement with the experimental results.
关键词:
laser
,
null
,
null
,
null
,
null
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
,
null
,
null
ZHAO Guozhen YU Jian Shanghai Research Institute of Meterials
,
Shanghai
,
ChinaZHANG Xiaozhong Tsinghua University
,
Beijing
,
China
金属学报(英文版)
The techniques for surface analysis including AES,XPS and SIMS were employed to study the chemical composition and bond valence of nitrogen ion implanted surface of surgical implantation service alloy Ti6Al4V.The depth of implanted nitrogen ions and the sputtering rate of argon beams were determined using a profilometer.It was found that the combination of injected nitrogen ions with titanium resulted in the formation of hard TiN particles and the profile of nitrogen concentration approximately displayed gaussian distribution.The total depth of implanted nitrogen is about 350 nm and its maximum concentration appears in the depth of about 140 nm from the surface,in which the concentration ratio of nitrogen to titanium may be up to 1.1.
关键词:
Ti6Al4V
,
null
,
null
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
,
microstructure
,
CCT diagram
Materials Science and Engineering a-Structural Materials Properties Microstructure and Processing
The specimens of Ti-6Al-4V alloy were irradiated under the simulated ion beams of hydrogen and nitrogen. The microstructures of the alloy before and after irradiations are characterized by SEM, TEM and XRD. Then the tensile and high cycle fatigue properties were examined on the irradiated and un-irradiated alloys. The results show that the tensile and fatigue properties decrease to a larger degree after irradiation with the hydrogen ions than that with the nitrogen ions. The brittleness induced by the double effects of the fined grains and TiH is the main reason why the mechanical properties decrease for the alloy irradiated with the hydrogen ions. While for the alloy irradiated with the nitrogen ions, the decreasing properties are induced by the single effect of the partly fined grains. Therefore, the irradiation, especially with the hydrogen ions, plays a deleterious role on the properties of the alloy. The mechanisms of irradiation effect on properties are partly same for the alloy irradiated with nitrogen and hydrogen ions. The specimen shows a dyeing effect on the surface of the specimen after irradiation, which has no much influence on the mechanical properties of the alloy. (C) 2010 Elsevier B.V. All rights reserved.
关键词:
Ti-6Al-4V alloy;Irradiation;Tensile;Fatigue;Hydrogen;Nitrogen;crack-growth;radiation;hydrogen
X.B. Tian
,
X.F. Wang
,
A.G. Liu
,
L.P. Wang
,
S. Y. Wang
,
B. Y. Tang and P. K. Chu 1)Advanced Welding Production & Technology National Key Laboratory
,
Harbin Institute of Technology
,
Harbin 150001
,
China 2)Department of Physics & Materials Science
,
City University of Hong Kong
,
China
金属学报(英文版)
The research on plasma immersion ion implantation has been conducted for a little over ten years. Much is needed to investigate including processing technlogy, plasma sheath dynamics, interaction of plasma and surface, etc. Of the processing methods elavated temperature technique is usually used in PIII to produce a thick modified layer by means of the thermal diffusion. Meanwhile plasma ion heating is more recently developed by Ronghua Wei et al[1]. Therefore the temeperature is a critical parameter in plasma ion processing. In this paper we present the theoretical model and analysize the effect of imlantation voltage, plasma density, ion mass,etc on the temperature rise.
关键词:
plasma immersion ion implantation
,
null
,
null
Applied Surface Science
Two groups of Mo/Si films were deposited on surface of Si( 1 0 0) crystal. The first group of the samples was prepared by both ion beam assisted deposition (IBAD) and metal vapor vacuum arc (MEVVA) ion implantation technologies under temperatures from 200 to 400 degrees C. The deposited species of IBAD were Mo and Si, and different sputtering Ar ion densities were selected. The mixed Mo/Si films were implanted by Mo ion with energy of 94 keV, and fluence of Mo ion was 5 x 10(16) ions/cm(2). The second group of the samples was prepared only by IBAD under the same test temperature range. The Mo/ Si samples were analyzed by X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), sheet resistance, nanohardness, and modulus of the Mo/ Si films were also measured. For the Mo/ Si films implanted with Mo ion, XRD results indicate that phase of the Mo/Si films prepared at 400 and 300 degrees C was pure MoSi2. Sheet resistance of the Mo/ Si films implanted with Mo ion was less than that of the Mo/Si films prepared without ion implantation. Nanohardness and modulus of the Mo/ Si films were obviously affected by test parameters. (C) 2007 Elsevier B. V. All rights reserved.
关键词:
molybdenum silicide;MEVVA;IBAD;nanohardness;mechanical-properties;adhesion strength;internal-stress;films;tin;nanoindentation;substrate;coatings;hardness;layer
Journal of Physics D-Applied Physics
With a self-consistent fluid model, we study the transport characteristics of the collisionless radio frequency (rf) sheath in a high density plasma and calculate the spatiotemporal ion density and the potential drop across the sheath in one rf cycle for an rf-bias frequency of 13.56 MHz. We also study the effects of the rf frequency on the voltage at the electrode, the sheath width, the ion energy distribution (IED) and the ion angular distribution (IAD) at the electrode. The simulated results indicate that the incidence angles of the ions impinging on the electrode are less than 8 degrees when the ion velocity in the direction perpendicular to the sheath field is assumed to be a Boltzmann distribution. It is concluded that the rf frequency plays a crucial role for the energy and angular distributions of ions impinging on the electrode surface, and the IED and IAD are affected by the plasma density and the rf-bias power.
关键词:
density plasma reactors;energy-distribution
材料科学技术（英）
Hexagonal AIN films have been obtained by arc ion plating at different negative biases. X-ray diffraction and scanning electron microscopy results show that AIN films with smooth surfaces and (002) preferred orientation are obtained at low biases, whereas those with coarse surfaces and (100) preferred orientation are obtained at high biases. The formation mechanism of AIN is analyzed and the experiment results are discussed. The effect of bias on adhesion strength has also been examined.
关键词:
AlN;AIP;preferential orientation;bias;thin-films;deposition
