Y. Huo
,
Y. Chen
,
X. Zu and M. Tu( Department of Metal Materials
,
Sichuan University
,
Chengdu 610065
,
China)( Department of Metal Materials
,
Sichuan University
,
Chengdu 610065
,
China)( Department of Metal Materials
,
Sichuan University
,
Chengdu 610065
,
China)( Department of Physics
,
Sichuan University
,
Chengdu 610065
,
China)
金属学报(英文版)
In this paper, a theoretical model was presented to simulate the stress-strain hysteresis and the inner hysteretic behaviors, which were observed for polycrystalline Ni-Ti and Cu-based shape memory alloys (SMAs) at various temperatures. It was assumed that the stress-strum hysteresis of the grains of a polycrystalline sample of SMAs was relatively simple and easy to be calculated. The texture of the sample was characterized by a distribution function, which could be obtained from the experiments. Thercfore,the model provided a means to simulate and, for the first time, to predict the stressstrain hysteresis at different loading temperatures for polycrystalline SMAs.
关键词:
shape memory alloys (SMAs); hysteresis; mathematical modeling of phase transition
何晓英
,
邓海英
,
李容
腐蚀科学与防护技术
doi:10.3969/j.issn.1002-6495.2005.04.007
采用交流阻抗法和极化曲线法研究了溴代十六烷基吡啶(CPB)和硫脲(TU)在复配前后对X70钢在H2SO3溶液中的缓蚀作用.研究发现:H2SO3的浓度为10 mmol/L、pH=3.7的HAc-NaAc缓冲体系中,溴代十六烷基吡啶(CPB)与硫脲(TU)的缓蚀率随着浓度的增加而增加,溴代十六烷基吡啶(CPB)的浓度达到5×10-6kg/L时的缓蚀性能最佳,而硫脲(TU)的浓度达到50×10-6kg/L时的缓蚀性能最佳.复配实验结果表明:当缓蚀剂的总浓度为25×10-6kg/L,溴代十六烷基吡啶(CPB)和硫脲(TU)复配质量浓度比为1:1时缓蚀效果最好.
关键词:
溴代十六烷基吡啶
,
硫脲
,
协同缓蚀
,
X70钢
,
电化学阻抗谱
Transactions of Nonferrous Metals Society of China
A simplified model was proposed targeting at the isotropic high porosity metal materials with well-distributed structure. From the model the mathematical relationship between elongation and porosity was deduced for those materials, and the relationship formula was derived generally for actual high porosity metals at last, whose validity is supported by the representative experiment on a nickel foam prepared by electrodeposition.
关键词:
high porosity metal material;elongation;porosity
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
Science in China Series E-Technological Sciences
A geometrical model has been established based on the structure feature of high porosity metal materials, the mathematical relationship between electrical resistivity and porosity for high porosity materials with even structure has then been deduced conveniently, and the formula for calculating the electrical resistivity of high porosity materials through porosity, which is easy to know, has been acquired further. Besides, the theoretical formula was verified to coincide with the test results well by the application taking nickel foam as an example.
关键词:
high porosity material;electrical resistivity;calculation formula;deduction;foams
P.Verma
,
O.P.P
,
ey
,
A.Verma
材料科学技术（英）
In the present work investigations have been made to see the role of metal oxides on the performance of the silver metal oxides electrical contact materials. Silver metal oxide materials of three different compositions Ag-10CdO, Ag-7.6SnO2-2.3In2O3 and Ag-10ZnO were prepared by internal oxidation process under identical processing conditions. These materials were tested for electrical conductivity, hardness, and erosion loss. Performing an accelerated test on the actual contactor assessed the electrical performance, involving erosion loss and temperature rise of the processed materials. The arc-eroded surface was characterized under scanning electron microscope. The study of the eroded surfaces of contacts indicates that the thermal stability of metal oxides depends on nature of silver-metal oxide interface and their mode of erosion. An attempt is made to correlate the surface features of the eroded contacts with the thermal stability of metal oxides.
关键词:
Contact material
,
null
,
null
Zhenfang LIAO
,
Shijin ZHANG
材料科学技术（英）
Electro-hydraulic impulse water-air mixing jet by which the quality of metal materials can be improved is described in this paper. The experimental results proved that the hardness and the micro-hardness of the surface layer of metal materials can be improved with this method, for example, the microhardness of CrWMn can be increased by 35.62 percent.
关键词:
Electro-hydraulic impulse
,
null
,
null
XU Xiangxing SU Yi ZHOU Wei Tsinghua University
,
Beijing
,
ChinaCAI Qigong Central Iron and Steel Research Institute
,
Ministry of Metallurgical Industry
,
Beijing
,
China XU Xiangxing
,
Dept.of Mechanical Engineering
,
Tsinghua University
,
Beijing
,
100084
,
China
金属学报(英文版)
The cleavage fracture mechanism of granular bainitie weld metal in 15MnVN steel has been investigated.SEM observation of a special specimen for revealing simultaneously fracture sur- face and microstructure shows that the cleavage of the weld is initiated by M-A constituent. The 95th percentile equivalent diameter of M-A constituent controls the cleavage fracture stress of the weld metal.
关键词:
granular bainite
,
null
,
null
,
null
