Started in 1985 Semimonthly
ISSN 1005-0302
CN 21-1315/TG
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The journal has been awarded the excellent periodical in China, and its articles are covered by SCI, EI, CA, SA, JST, RJ, CSA, MA, EMA, AIA etc., PASCAL web. ISI web of Science,SCOPUS.

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      28 September 1994, Volume 10 Issue 5 Previous Issue    Next Issue
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    Articles
    Friction of Alloys at High Temperature
    M.B.Peterson (Wear Sciences, 925 Mallard Circle, Arnold Maryland 21012, USA)(To whom correspondence should be addressed)S.J.Calabrese (Rensselaer Polytechnic Institute, Troy, NY, USA)Shizhuo LI; and Xiaoxia JIANG (Institute of Metal Research, Chinese Acad
    J. Mater. Sci. Technol., 1994, 10 (5): 313-320. 
    Abstract   HTML   PDF (1555KB)
    A brief review is given about the friction and wear properties of high temperature alloys. Above a critical temperature, if the oxide becomes ductile, it will flow over the surface and prevent metal-to-metat contact. In order to study the tribology of oxide lubrication. a series of tests were carried out using Cu(ReO4)2 as a lubricant. The effects of time. Surface finish. substrates. load and temperature were investigated. A mechanism of lubrication is proposed in which the surface slip predominates along with mechanical attachment of oxide to the surface.
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    Stoichiometry Effects in TiAl and TiAlCr Alloys
    P.A.Beaven ;and Th.Pfullmann (Institute for Materials Research, GKSS-Research Centre, Geesthacht F.R.G)(To whom correspondence should be addressed)
    J. Mater. Sci. Technol., 1994, 10 (5): 321-330. 
    Abstract   HTML   PDF (2926KB)
    Analytical electron microscopy methods have been used to establish correlatjons between lattice parameters and phase compositions in binary TiAl and ternary TiAlCr alloys based on Ti-48 at.-%Al.On traversing the stoichiometric composition in the binary TiAl system the lattice parameters show linear relationships with Al concentration suggesting antisite defects influence the structural parameters. The relationship between lattice parameters and phase composition in the ternary TiAl (Cr) phase is influenced by the site occupation behaviour of Cr in the TiAl lattice. Comparisons are made between" bulk" and" local" measurements for obtaining such information in complex two-phase alloys. Possible implications for the mechanical properties are briefly discussed.
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    Comparison of K_(IC) Values for SiC Whisker Reinforced Ceramic Composites Obtained by Using Various Methods
    Tingquan LEI; Guangyong LIN; Shuangxi WANG; and Yu ZHOU (Dept. of Metals and Technology, Harbin Institute of Technology, Harbin, 150001, China)(To whom correspondence should be addressed)
    J. Mater. Sci. Technol., 1994, 10 (5): 331-340. 
    Abstract   HTML   PDF (1577KB)
    The fracture toughness (KIC) values determined by indentation microfracture method (IM ) for SiC whisker reinforced Al2O3 and ZrO2 based composites were calculated with different IM equations and compared with those obtained by singte edge notched beam (SENB) technique. Experimental results show that the KIC (IM) values calculated with different equations are quite different one from another. For composites without phase transformable components the KIC (IM) and KIC (SENB) values are practically on the same level, but for composites with phase transformable components (partially stabilized zirconia) the KIC (SENB) values are always higher than KIC (IM). This is because that the IM method can not reveal sensitively the toughening effect due to dynamic t-m transformation of ZrO2 as the SENB method does. The accuracy of the IM method depends on the Suitability of the IM equations and was evaluated for the materials used in this investigation. Two new IM equations are suggested with which the KIC (IM ) values can be obtained very close to KIC (SENB) values for composites having phase transformable components.
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    Microstructure of the Ductile Phase in Intermetallic Compound Ni_(50)Al_(20)Fe_(30)
    Lianlong HE; Shuhe WANG; Jianting GUO; and Hengqiang YE (Lab. of Atomic Imaging of Solids, Institute of Metal Research, Academia Sinica, Shenyang, 110015, China)(To whom correspondence should be addressed)
    J. Mater. Sci. Technol., 1994, 10 (5): 341-346. 
    Abstract   HTML   PDF (4361KB)
    The microstructure of the single hot extruded and annealed Ni50Al20Fe30Y0.003 intermetallic compound alloys has been examined by means of high resolution electron microscopy (HREM). In these extruded and annealed alloys. the ductile phase is of a mixture of the disordered fcc γ matrix and or dered γ' precipitates. This fact well interprets the reason why the degree of annealing treatment can influence the strength and ductility of these alloys. The HREM observation revealed directly that there was some strain concentration at γ'-γ interfaces, due to the presence of more iron atoms in these two phases. The fixed orientation relationship between the γ phase and γ' precipitates was identified to be {001}γ{00 }γ' and <100 >γ < 100 > γ'
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    Investigation on Cracking in the Surfacing Welding Layer of Ni_3Al Based Alloy
    Guangwei HAN; Di FENG; and Wujun YE (Dept.5, Central Iron and Steel Research Institute, Beijing, 100081, China)(To whom correspondence should be addressed)
    J. Mater. Sci. Technol., 1994, 10 (5): 347-350. 
    Abstract   HTML   PDF (1981KB)
    Investigation has been made into the causes of cracking in the Surfacing welding layer of Ni3Al based alloy by analysing both the liqu id-to-solid transformation in the molten pool and the distribution of thermal stress within the surfacing welding layer. The results show that cracking in the surfacing welding layer is directly related to the producing of eutectic phase β' (NiAl) in the interdendritic region and high thermal stress within the surfacing welding layer. When the process of electric arc surfacing welding is changed from along straight line to along" Z" pattern, cracking in the surfacing welding layer of Ni3Al based alloy is prevented due to being reduced of both the cooling rate of liquid in the molten pool and the moving speed of the heat source. Reducing the melting volume of the substrate material by lowering the output power of electric arc welding would make the content of iron atoms in the molten pool decrease. and this also can reduce the trend of the eutectic reaction in the interdendfitic region and is helpful to Suppress cracking in the surfacing welding layer.
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    Synthesis of Polycaprolactone with Two Carboxyl End Groups
    Qijin ZHANG; Wenying XU; and Zhiyong WANG (Dept. of Mater. Sci. & Eng., University of Science and Technology of China, Hefei, 230026, China)(To whom correspondence should be addressed)(Dept. of Modern Chemistry, University of Science and Technology of Ch
    J. Mater. Sci. Technol., 1994, 10 (5): 351-354. 
    Abstract   HTML   PDF (338KB)
    At 225℃. caprolactone has been polymerized in the presence of succinic acid under dry nitrogen atmosphere. Characterizations of the polymer through IR and molecular weight measurements by 1H-NMR and end group titration have shown that the polycaprolactone obtained is of two carboxyl end groups. The molecular weight of it increases with decreasing of the acid content in the reaction mixture under the same polymerization conditions. With a certain ratio of acid to caprolactone. the maximum of molecular weight of the polymer will be reached at the reaction time of 3h.
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    Enhanced Bamboo Reinforced Aluminum Laminates
    Shihong LI; Shaoyun FU; and Benlian ZHOU (Int. Centre for Mater. Phys., Institute of Metal Research, Chinese Academy of Science, Shenyang, 110015, China)Qiyun ZENG; and Xianrong BAO (Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, 11
    J. Mater. Sci. Technol., 1994, 10 (5): 355-358. 
    Abstract   HTML   PDF (1292KB)
    A new technique has been developed for flattening circular natural bamboo culm to plate form for remarkably enhancing its mechanical properties, The enhanced bamboo, cheaper than Al, is then used to reinforce an aluminum alloy for civilian applications. The properties of the composite are greatly enhanced compared to those of the Al alloy. The Al protects bamboo from bioerosion and improves hygroscopicity
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    Phase Relations in TiAl+Nb System
    Jingguo WANG; Guoliang CHEN; and Zuqing SUN (State Key Lab. for Advanced Metal Materials, University of Science and Technology Beijing, Beijing, 100083, China)Hengqiang YE (Lab. of Atomic Imaging of Solids, Institute of Metal Research, Academia Sinica, Sh
    J. Mater. Sci. Technol., 1994, 10 (5): 359-366. 
    Abstract   HTML   PDF (3783KB)
    The microstructures and phases of ternary TiAl+Nb alloys containing 50-60 at.-%Al, 0-21 at.-%Nb have been studied using transmission electron microscopy (TEM) and X-ray powder diffraction. The phases present in the alloys and their distribution were found to be a sensitive function of composition. The phase relations between γ-TiAl and γ1 (a new ordered ternary intermetallic compound based on γ-TiAl) were determined. Essentially single γ phase was determined for alloys with relativety low Nb content (≤10 at.-%Nb). the γ1 phase was determined to exist in the composition range containing higher Nb contents (15-21 at.-%Nb). Between γ and γ1 phases, with intermediate Nb contents there is a transitional phase γ1 (a superstructure of γ-TiAl). As for the influence of Al concentration on the phase relations. the γ1 phase was inclined to form in the alloys with relatively high Al contents. The ordering transformation of γ, to γ1 is a continuous ordering process and the transition may be second order.
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    Microstructure and Mechanical Properties of a Duplex Martensite Austenitic Steel Precipitation-hardened by VC Carbide
    Changsheng XIE; Jiansheng ZHAO; Peizhen SUN; and Xia LIANG (Dept.of Mech. Eng. Ⅱ, Huazhong University of Science and Technology, Wuhan, 430074, China)(To whom correspondence should be addressed)
    J. Mater. Sci. Technol., 1994, 10 (5): 367-373. 
    Abstract   HTML   PDF (1652KB)
    This paper presents an investigation on the primary microstructure and mechanical properties of a martensite-austenitic duplex steel precipitation-hardened by VC carbide. The results show that the mechanical properties at room temperature are strongly dependent upon the volume fraction of austenite fA. When fA < 32 % both ultimate strength and Vield strength are decreased with increasing fA. however. whenfA>32%, with increasing the.fA. ultimate strength rises and yield strength drops down. Experimental results at elevated temperatures. show that when test temperature ≤500℃. the yield strength to modulus ratio remains unchanged, however. as the temperature rises a substantial fall in the ratio occurs. The strength values at 600 and 700℃ are increased with increasing strain rate measured by cross-head speed of testing rnachine, The law of mixtures and the contribution of strain-induced transformation from unstable austen ite to martensite to the mechanical properties are discussed.
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    A Constitutive Model for Hot Pressing of Powders
    Rongde GE (Dept. of Nonferrous Metallurgy, Central South University of Technology, Changsha, 410083, China)
    J. Mater. Sci. Technol., 1994, 10 (5): 374-380. 
    Abstract   HTML   PDF (613KB)
    Based on an assumption that the effective pressure in hot pressing related to the applied pressure varies with the relative density of the compact in a power law form. a three-dimensional viscoelastic model that depicts the viscoelastic detormation behaviour of powder compacts in hot pressing has been developed. It has been shown by the experimental data that the proposed model in which the parameters are determined by means of nonlinear regression analysis can be used to describe the density-time relationship for the hot pressing of pure magnesium oxide and atomized iron powders and to estimate the end-point relative density of the compact.
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    Energy Minigaps in the Quantum Well Wires with Periodical Lateral Surface Structures
    Zhenyan DENG; Hong SUN; and Shiwei GU (Dept. of Applied Physics, Shanghai Jiaotong University, Shanghai, 200030, China)(To whom correspondence should be addressed)(Present address: No .5 Dept.. Shanghai Institute of Ceramics.Chinese Academy. of Sciences.
    J. Mater. Sci. Technol., 1994, 10 (5): 381-385. 
    Abstract   HTML   PDF (425KB)
    Energy minigaps caused by lateral surface structures in quasi-one-dimensional GaAs/ AlAs quantum well wires are calculated with the variational and degenerate-perturbational approaches.By a coordinate transformotion. the structured interfaces of the wires are transformed into planar ones so that the boundary conditions of the electronic wave functions can be satisfied exactly on the interfaces. The dependence of the energy minigaps on the lateral surface structures are discussed.
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    Spherical Asymmetric Solution for Point Defect
    A. G.Ivanchin (Institute of Strength Physics and Materials Science, Siberian Branch of Russian Academy of Sciences,Tomsk, 634055, Russia)
    J. Mater. Sci. Technol., 1994, 10 (5): 386-388. 
    Abstract   HTML   PDF (235KB)
    The article proves unsingleness of solution for the known elastic equilibrium equation for point defect. Another linear-independent solution. meeting the same boundary conditions as the classical one, has been found.
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    A Preparing Process of Quick-moving Leaf for TiNi Alloy
    Zichang SHAO; Jingcheng WANG; and Wei ZHANG (No. 1 Materials Research Dept., Shanghai Iron and Steel Research Institute, Shanghai, 200940, China)(To whom correspondence should be addressed)
    J. Mater. Sci. Technol., 1994, 10 (5): 389-390. 
    Abstract   HTML   PDF (185KB)
    This paper reports a preparing process of quick moving leaf for TiNi shape memory alloy. Using the process. a series of quick moving leaves having different points of temperature. from 58 to 100℃. at which they jump up have been made. The quick moving leaves will be fully qualified as the electric switches that open and close themselves at proper temperatures.
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ISSN: 1005-0302
CN: 21-1315/TG
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