ISSN 0412-1961
CN 21-1139/TG
Started in 1956

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    , Volume 31 Issue 14 Previous Issue    Next Issue
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    MATHEMATICAL SIMULATION OF MAGNETIC FIELD IN ESR SYSTEM
    WEI Jihe(Shanghai University; 200072); REN Yongli; (Xi'an Institute of Metallurgy and Construction Engineering; 710055)(Manuscript received 94-04-27)
    Acta Metall Sin, 1995, 31 (14): 51-60. 
    Abstract   PDF (655KB) ( 743 )
    A mathematical simulation and its application to laboratory 200 mm diameter mould of ESR unit were developed based on Maxwell's equations and related electromagnetic field theorem. For remelting a low carbon alloy steel(an electrode of 76 mm in diameter, 3000 A current (rms) and the slag of CaF2+30 mass-% Al2O3+20 mass-% CaO system) with the parameturs selected reasonably,the amplitude magnetude of magnetic field intensity inner the electrode along the formation direction of electrode tip cone is continuously increasing to a maximum value being about 2.6×104 A/ m near the cone top, then decreasing in the slag bath, ingot pool, mushy zone and solid ingot. For a high speed steel(M2) ingot on another unit with a mould of 140 mm in diameter (80 mm diameter electrode and the slag of CaF2+CaO+Al2O3+MgO system), the predicted magnitude and profile of the magnetic field intensity in the slag bath and ingot pool of the system by the model are in pretty good agreement with the practical measurements. This model may be used as a good and reliable basis for the further study on the fluid flow and the heat and mass transfer processes in ESR system .Correspondent: WEI Jihe, professor,(Department of Materials Science and Engineering, Shanghai University,Shanghai 200072)
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    STUDY ON MULTIPLE-LAYER STRUCTURE OF PASSIVE FILM ON STAINLESS STEEL BY POTENTIOSTATIC-GALVANOSTATIC (P-G) TRANSIENT TECHNIQUE Ⅰ. P-G Response Characteristics of Passive Film with Multiple-Layer Structure
    SONG Shizhe; Tang Zilong(Tianjin University; 300072)(Manuscript received 940-01-11; in revised form 94-05-27)
    Acta Metall Sin, 1995, 31 (14): 61-66. 
    Abstract   PDF (448KB) ( 535 )
    Potentiostatic-Galvanostatic (P-G) transient technique has been applied to study the multiple-layer passive films. The characteristics of P-G response curves obtained at different passive stages can be used to determine whether there exist multiple-layer structure on passive film or not. Two character parameters were proposed to indicate the stability between the layes. Further, a mathematical model was set up for the P-G response curve. The results proved that the new model can illustrate well the P-G response characteristics of the tested systems Correspondent: SONG Shizhe, professor,(Department of Materials Science and Engineering, Tianjin University, Tianjin 300072)
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    STUDY ON MULTIPLE-LAYER STRUCTURE OF PASSIVE FILM ON STAINLESS STEELS BY POTENTIOSTATIC-GALVANOSTATIC (P-G)TRANSIENT TECHNIQUE Ⅱ. Structure and Growth of Passive Film for 2205 and 316L Stainless Steels in 2.5 mol / L H_2SO_4
    TANG Zilong; SONG Shizhe (Tianjin University; 300072)(Manuscript received 94-01-05; in revised form 94-05-27)
    Acta Metall Sin, 1995, 31 (14): 67-72. 
    Abstract   PDF (467KB) ( 571 )
    Potentiostatic-Galvanostatic(P-G)transient technique has been applied to study the structure of passive films on 2205 and 316L stainless steels in 2.5 mol/ L H2SO4.The results proved that the passive films for the both possese multiple-layer structure. By fitting the P-G response curves, the dependence of the electrochemical parameters on the polarized potentials and time was obtained. On the basis of these results, the stability and the growth the rules of passive films were discussed.Correspondent:SONG Shizhe, professor,(Department of Materials Science and Engineering, Tianjin University, Tianjin 300072)
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    MoSSBAUER EFFECT ON BALL-MILLED NANOCRYSTALLINE Fe MATERIALS
    CHEN Hong; XU Zuxiong; ZHAI Shaoyan; M A Ruzhang(University of Science and Technology Beijing; 100083)(Manuscript received 94-03-16; in revised form 94-08-16)
    Acta Metall Sin, 1995, 31 (14): 73-76. 
    Abstract   PDF (325KB) ( 445 )
    Nanocrystalline metallic iron powder was prepared under either Ar or N2 atmosphere by a vibratory ball mill. The X-ray diffractions (XRD) were used to monitor the structure changes during ball milling. Nanostructure of metallic Fe was further studied by Mssbauer effect. The structure of the electron and magnetism of the interface component in Fe nanocrystals was abviously effected by the milling atmosphere.Correspondent: XU Zuxiong, professor,(Department of Material Physics, University of Science and Technology Beijing, Beijing 100083)
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    SIMULATION OF ELASTO-PLASTIC DEFORMATION OF In-Situ Al-Al_2Cu COMPOSITE BY CRYSTALLINE MACRO-MICRO MECHANICAL APPROACH
    WANG Mingzhang; LIN Shi; QIAN Rengen; XIAO Jimei(University of Science and Technology Beijing; 100083)(Manuscript received 94-04-18; in revised form 94-10-07)
    Acta Metall Sin, 1995, 31 (14): 77-85. 
    Abstract   PDF (748KB) ( 707 )
    A crystalline macro-micro mechanical approach is developed to analyze the mechanical behaviour of metal matrix composite numerically,on the basis of the data of single crystal deformation. The tensile deformation is simulated in particular using a model system Al-Al2Cu in-situ composite. The calculated stress-strain curves agree well with the experiment result by Davidson et al. The initiation and growth of matrix slip deformation and the inhomogeneous distribution and variation of the stress in the specimen especially near the interface are obtained.The effect of matrix/ reinforcement interface and interlamellar spacing λ on the stress-strain behaviour of metal matrix composite are investigated. It is shown that the crystal macro-micro mechanical approach, which can provide some useful information to insight into the deformation mechanism, is very helpful to analyze and design the mechanical properties of metal matrix composite.Correspondent: WANG Mingzhang,(Department of Material Physics, University of Science and Technology Beijing, Beijing 100083)
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    BETTERMENT ON INTERFACE OF C_F/Al COMPOSITES
    WANG Yuqing; TANG Fengjun; ZHENG Jiuhong(Institute of Metal Research;Chinese Academy of Sciences;Shenyang 110015); ZHOU Benlian(Institute of Metal Research; International Centre for Materials Phisics; Chinese Academy of Sciences;Shenyang 110015)(Manuscript received 94-03-11;in revised form 94-06-01)
    Acta Metall Sin, 1995, 31 (14): 86-90. 
    Abstract   PDF (380KB) ( 503 )
    An approach to better the interface of the CF/Al composites was carried out on the optimization of the technological parameters for coating of the C fibres and in squeeze casting process. The optimized temperatures of preform, Tf, for bare or PCS SiC-coated C fibres and of molten metal, Tm, Al-10Si matrix seem to be matched by 733 K and 1033 K or 753 K and 1053 K respectively. The quality of interface in composites is different from the coating of C fibres. Such coating, either to retard the interfacial reaction or to better the bonding state, may improve the strength of composites, e.g., increase of strength of a composite up to 89% by PCS SiC-coating and also improvement of wettability by K2ZrF6 solution. The strength of composites increases with the increase of the interfacial shear stress. Furthermore,the optimized shear stress of M40/Al composites with high modulus C fibers is higher than that of the CF/Al composites with low modulus fibers, thus the higher tensile strength was obtained.Correspondent: WANG Yuqing,(associate Professor, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110015)
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    POSITRON ANNIHILATION LIFETIME ANALYSIS OF 8090 ALLOY WITH DOPING Zn, Ag OR Sc UNDER CRYOGENIC TEMPERATURES
    GAO Yingjun; WU Weiming; FENG Guanzhi; XU Shaojie; RUAN Xiangdong(Guangxi University; Nanning 530004)(Manuscript received 94-03-11)
    Acta Metall Sin, 1995, 31 (14): 91-96. 
    Abstract   PDF (451KB) ( 493 )
    The positron annihilation lifetime of 8090 alloy and that added Zn, Ag or Sc were measured in the temperature range of 25—273 K. Results showed that the short life component of τ1 = 175—187 ps is a typical positron annihilation lifetime incoherent δ'(Al3Li) phase particles, and the long one τ2 is obviously dependent on temperature.The temperature dependence of τ2 in 4 alloys can be well interpreted and the behaviour of vacancy be deduced as long as the influence of both vacancy and grain boundray on τ2 is considered.Correspondent: GAO Yingjun, lecturer,(Department of Physics, Guangxi University, Nanning 530004)
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