XU Zuyao (T.Y.Hsu) ZHOU Xiaowang~** Department of Materials Science
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Shanghai Jiaotong University
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Shanghai
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China Now at Department of Materials Strength (Department No.1)
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Shanghai Research Institute of Materials
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Shanghai
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200030 China
金属学报(英文版)
An approach for the thermodynamics of the thermoelastic martensitic transformation in β-Cu base alloys is suggested.Driving forces for martensitic transformation,T_0 and M_s tempera- tures in Cu-Zn,Cu-Al and Cu-Zn-Al alloys were calculated and the calculated M_s are in good agreement with the experimental ones.Ordering of the parent phase lowers M_s(T_0)in Cu-Zn and Cu-Zn-Al alloys,but raises M_s(T_0)in Cu-Al alloys.Two methods for the es- timation of the critical driving force for the thermoelastic martensitic transformation are also introduced.
关键词:
β-Cu base alloy
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null
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QIAO Lijie LIU Rui XIAO Jimei University of Science and Technology Beijing
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Beijing
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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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Shaoxiong ZHOU
材料科学技术（英文）
The discovery of the first Fe-based ferromagnetic amorphous alloy in 1966 had made an impact on conventional magnetic materials because of its unique properties. Since then, a number of amorphous magnetic materials have been successfully developed and used in a wide variety of applications. A brief review of R & D activities on amorphous soft magnetic materials in China is given from the beginning to the present in a somewhat chronological order, followed by a brief introduction to their applications on electric and electronic industries. An analysis and a prospect of Chinese market of such amorphous materials are also presented.
关键词:
MA Zongyi YAO Zhongkai Harbin Institute of Technology
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Harbin
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China
金属学报(英文版)
The SiC_w/Al composite prepared by squeeze casting has a combination of superior room temperature specific strength and modulus together with excellent thermal properties.The extrusion can make an improvement on the strength and ductility of the composite from 582 MPa as squeeze casted up to 639 MPa,and on the transformation from isotropic to the anisotropic structure.This seems to be explained by the orientation of whiskers and the densification of dislocations in matrix.TEM observation indicates that the stacking fault is the usual planar defect on the SiC_w surface. composite;;SiC whisker;;Al alloy;;microstructure
关键词:
composite
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Transactions of Nonferrous Metals Society of China
Based on the simplified structure model of high porosity materials, the formulas for approximately evaluating the tensile strength of these materials have been derived from the corresponding deductions taken by means of the relative theories about geometry and mechanics. The results show that, the tensile strength of these materials not only associates with the material sort and production method, but do further have a direct value relationship with the porosity, theta. This value relationship can be specifically expressed by the power of the item (1 - theta), and it makes the tensile strength variation display a complicated nonlinear law with the porosity. In addition, the application of those formulas has been investigated with the corresponding experiment on a nickel foam.
关键词:
high porosity material;tensile strength;evaluation
Journal of Applied Physics
The dependence of yield strength, uniform elongation, and toughness on grain size in metallic structural materials was discussed. The toughness is defined as the product of yield strength and uniform elongation. The yield strength versus grain size can be well described by the Hall-Petch relation; however, the uniform elongation versus grain size is not well understood yet. A simple model involving the densities of geometrically necessary dislocations and statistically stored dislocations was proposed to estimate the uniform elongation versus grain size. Existing data for low carbon steels and aluminum indicate that, in the grain size less than 1 mu m, the materials usually exhibit high strength and low uniform elongation and, in the grain size greater than 10 mu m, the materials usually exhibit low strength and high elongation; in either case the toughness is low. However, in the grain size of several micrometers, the toughness is the highest. It is suggested that we should pay more attention to develop the metallic materials with grain size of several micrometers for structural applications. (c) 2007 American Institute of Physics.
关键词:
nanocrystalline copper;nanostructured metal;steels;deformation;ductility;law
