W. H. Tian
,
S.L. Hu and M. Nemoto(Department of Materials Physics
,
University of Science and Technology Beijing
,
Beijing 100083
,
China)(Department of Materials Forming
,
University of Science and Technology Beijing
,
Beijing 100083
,
China)(Department of Materials Science and Engineering
,
Faculty of Engineering
,
Kyushu University
,
Fukuoka 812
,
Japan)
金属学报(英文版)
The Co3 Ti phase hardens appreciably by the fine precipitation of disordered fcc Co-rich phase upon aging after quenching from solution annealing temperature. Transmission electron microscope (TEM)observations revealed that the precipitates are platelet in shape, lying nearly parallel to the {100} planes of the L12-ordered matrix, and perfectly coherent with the matrix lattice at the beginning of aging. The high temperature strength increases appreciably with the fine precipitation of disondered Co-rich phase over the whole temperature range investigated. TEM observations of the deformed alloys after underaging revealed that saperdislocations are pinned by precipitates indicating an attractive interaction between dislocations and precipitates.
关键词:
Co_3 Ti
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null
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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
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null
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null
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Douxing LI and Hengqiang YE (Laboratory of Atomic imaging of Solids
,
Institute of Metal Research
,
Chinese Academy of Sciences
,
Shenyang
,
110015
,
China)
材料科学技术（英文）
The present paper summarizes the current status of high resolution electron microscopy (HREM)and the applications of HREM to materials science and condensed matter physics. This review recounts the latest development of high resolution electron microscope, progress of HREM and the applications of HREM, including the crystal structure determination of microcrystalline materials and characterization of the local structure of the defects and nanostructured materials as well as qualitative and quantitative analysis of the grain boundaries, interfaces and interfacial reactions in the advanced materials by means of HREM in combination with electron diffraction,subnanometer level analysis, image simulation and image processing.
关键词:
Wei LIU
材料科学技术（英文）
Transformation induced plasticity (TRIP) and twinning induced plasticity (TWIP) effects had been widely studied in single austenite steel. But in duplex γ & α(δ) phase, such as welding materials of stainless steel, they had been less studied. Tensile shear loading experiment of resistance spot welding specimens prepared with 2 mm 301L sheets, was carried out at 15℃ and -50℃. Optical microscopy and scanning electron microscopy (SEM) as well as X-ray diffraction (XRD) were used to investigate the microstructure of weld nugget, and specimens fracture surface. The results showed that the initial weld nugget was composed of 8.4% α(δ) ferrite and 91.6% austenite. Tensile shear load bearing capacity of spot welding specimen at -50℃ was 24.8 kN, 17.7% higher than that at 15℃. About 78.5 vol. pct. martensite transformation was induced by plastic deformation at -50℃, while about 67.9 vol. pct transformation induced at 15℃. The plasticity of spot welding joint decreased with the decline of experimental temperature.
关键词:
301L stainless steel
,
stainless
,
steel
,
Resistance
,
spot
,
wel
Hengzhi FU
,
Xingguo GENG
材料科学技术（英文）
The present paper aims to the characterization of high rate direction solidification on AI-Mn and AI-Cu alloys. It is indicated that the relevant cooling rate of high rate directional solidification is defined within 10(0)～10(3) K/s that is located in the region between near-equilibrium slow growth rate and rapid solidification rate beyond equilibrium condition, and at the meantime there occurred a series of turning effect of interface stability and morphologies. With the increase of growth velocity the interface with planar front evolved to cells and dendrites at the stage of near-equilibrium and with further increase of growth rate they transformed reversely from dendrites to cell structure and then to absolute stability of planar interface. An explanation based on effective constitutional supercooling about the evolution of interface morphologies with the change of growth rate was proposed.
关键词:
J.H. Xie
,
Y.S. Wu
,
J.Q. He
,
X.Z.Yang and R.Z. Zhu (Department of Surface Science & Corrosion Engineering
,
University of Science and Technology Beijing
,
Beijing 100083
,
China)
金属学报(英文版)
This paper investigates the corrosion fatigue (CF) crack initiation behavior of 316L stainless steel in Hank's solution which simulates bodylike fluid. The CF experiments were conducted under the conditions of electrochemically accelerated, free immersion and pre-polarized pitting potential. The results showed that 316L stainless steel was susceptible to pitting corrosion in Hank's solution. Intergranular corrosion occurred obviously at the bottom of pits where the CF cracks initiated by the combined action of alternating stress and corrosive medium for the notch effect of stress concentrated in the grain boundaries.The CF crack propagation is both intergranular and transgranular.
关键词:
: aritificial joints
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