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

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    , Volume 28 Issue 11 Previous Issue    Next Issue
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    APPLICATION OF MOLECULAR ORBITAL THEORY TO ANALYSIS OF PHASE STABILITY FOR ALLOYS
    YIN Hong; TAO Kun; PAN Jinsheng; LI Hengde (Tsinghua University; Beijing)
    Acta Metall Sin, 1992, 28 (11): 1-9. 
    Abstract   PDF (787KB) ( 589 )
    In this paper, the application of molecular orbital theory to the analysis of phase stability of alloys is outlined. The critical M_d values (M-_(dc)) of the γ/(γ+σ),γ/(γ+μ) and γ/(γ+γ') phase boundaries in some ternary alloy phase diagrams at various temperatures are calculated by averaging the M_d values of several selected characteristic points at the phase boundaries. Approximate equations for the temperature dependence of the critical M_d of γ/ (γ+σ), γ/ (γ+μ) and γ/(γ+γ') phase boundaries are established. The accuracy of the analysis is discussed in detail. It is found for the first time that the average value of the bond order, B_o ,at the phase boundaries is also approximately a constant and therefore a critical average bond orderB_(oc). like M_(dc), can be introduced for the analysis of phase stability.
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    论文
    FORM AND EFFECT OF Zr IN CuCoBeZr ALLOY
    LIU Hefa; SUN Naizhen; DAI Xueli; REN He(Zhenjiang Shipbuilding Institute; Zhenjiang; Jiangsu) LI Lijun (Shanghai Electrical Machinery Plant; Shanghai)
    Acta Metall Sin, 1992, 28 (11): 10-14. 
    Abstract   PDF (2159KB) ( 906 )

    Precipitation form of Zr in CuCoBeZr alloy during solidification, cooling and final aging, as well as its effect on the high temperature properties have been studied and discussed. Results show that during solidification and cooling, Zr precipitates as fine particles, Cu_3Zr, which prevents α-Cu grains from growing and provides more nuclei for CoBe and hence leads to finer primary CoBe. Fine Cu_3Zr particles also precipitate during aging. Because Cu_3Zr is difficult to coalesce at high temperatures, the recrystallization temperature increases and the high temperature mechanical properties improve.

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    EFFECTS OF Cr AND Nb ON MICROSTRUCTURE AND MECHANICAL PROPERTIES OF Fe_3AI ALLOYS
    SUN Chao; GUO Jianting; TAN Minghui; LI Hui; WANG Shuhe(Institute of Metal Research; Academia Sinica; Shenyang)
    Acta Metall Sin, 1992, 28 (11): 15-19. 
    Abstract   PDF (1567KB) ( 526 )
    The effects of Cr and Nb on the tensile properties at room and elevated temperatures, and also on the microstructure has been investigated. An improvement in the ductility plasicity and the cleavage strength of Fe_3Al may result from adding Cr, it is more obvious at over 400℃. The Fe_2Nb containing Al precipitates in the Fe_3Al+Nb alloy, the particles provide significant strengthening. Additions of Cr and Nb in Fe_3Al provid a significant improvement in the yield strength at 550℃.
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    PATTERN RECOGNITION APLLIED TO STABILITY OF FILLED Ti_2Ni PHASES
    ZHOU Diangen; CHEN Nianyi (Shanghai Institute of Metallurgy; Academia Sinica; Shanghai)
    Acta Metall Sin, 1992, 28 (11): 20-22. 
    Abstract   PDF (214KB) ( 571 )
    Pattern recognition method is used for the investigation of stability region of filled Ti_2Ni phases in multi-dimensional bond-parameter space: The filling of C, N and O atoms into T_6 octahedra consisting of atoms of early-transition elements makes the expansion of the stability region of Ti_2Ni phase, and the relative stability of Al_2Cu and MoSi_2 type compounds decreases after the introduction of non-metallic elements such as C, N and O.
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    HYDROGEN PERMEATION AND DIFFUSION IN ALLOY INCOLOY 903
    XU Jian; SUN Xiukui; CHEN Wenxiu; LI Yiyi (State Key Laboratory of RSA; Institute of Metal Research; Academia Sinica)
    Acta Metall Sin, 1992, 28 (11): 23-27. 
    Abstract   PDF (405KB) ( 554 )
    Permeability and diffusivity of hydrogen in Fe-Ni-Co-based superalloy Incoloy 903 were measured over the temperature range of 220 to 420℃ using a gaseous permeation technique. The effect of strengthening phase γ' precipitated after being aged on the hydrogen permeation and diffusion was investigated. It was indicated that the permeability and diffusivity of hydrogen in the alloy hardly depend on heat treatment condition and are not affected by γ' phase precipitated after being aged. The relationships between the permeability and diffusivity of hydrogen and the temperature can be respectively expressed as = 9.36×10~(-5)exp[-54.20(kJ / mol) / RT]mol / m · s · MPa~(1/2) and D = 4.24 × 10~(-7)exp[-49.07(kJ / mol) / RT] m~2 / s.
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    RELATIONSHIP BETWEEN CREEP PROPERTIES AND STRUCTURE OF STEEL 20Cr11MoVNbNB
    FU Changpu; HAN Yong; LUShuangyun; AN Yunzheng (Shaanxi Mechanical Engineering Institute; Xi'an) PAN Jingda; DU Wenfeng(Beijing Heavy Electric Machine Works)
    Acta Metall Sin, 1992, 28 (11): 28-31. 
    Abstract   PDF (330KB) ( 518 )
    Studies were made of the creep properties and structure change of steel 20Cr11MoVNbNB at 550—650℃. It is found that at 550℃ when creep stress > 180MPa, there exists linear relation with two different slopes β_1 and β_2 between transitional creep strain ε_β and creep time t~(1/3), and β_1 (in initiol period) > β_2 (in later period). The Creep rate of stable stage at 550℃ can be expressed as ε_(11) = Aσ~nexp(-Q_c/RT), where, n=4.7, A exp(-Q_c/RT) = 5.37×10~(-16). Apparent creep active energy Q_c= 430kJ/mol at 550-650℃, which is much higher than the self-diffusion active energy of atoms for matrix Fe. In creep process, as creep stress and time increase, total weight of precipitated phases and relative weight of Cr, Mo and V increase, but those of Fe and Nb decrease in precipitated phases.
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    FRACTAL ANALYSIS OF FRACTURE SURFACE OF WELDING JOINT UNDER LOW CYCLE FATIGUE
    NI Yushan; CHENG Guangxu; KUANG Zhenbang (Xi'an.iaotong University)
    Acta Metall Sin, 1992, 28 (11): 32-39. 
    Abstract   PDF (947KB) ( 650 )
    Hausdorff dimension of fracture surface roughness of welding joint, both weld metal and heat-affected zone, of pressure vessel steel 16MnR, tested under strain-controlled low-cycle fatigue, was examined with computer vision system and by two-dimensional variation method. Results show that it decreases with the increase of cyclic hysteresis energy. The Hausdorff dimension variation at heat-affected zone is higher than that of weld metal. It is believed that the higher the fractal dimension is, the longer the fatigue life will be.
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    TEM STUDY OF MECHANISM OF STRAIN-AGE HARDENING OF INITIALLY DISORDERED (Co, Fe)_3V ALLOY
    LIN Yijian (Shanghai Iron and Steel Research Institute); S.GIALANELLA (University of Trento; Italy); R. W. CAHN (University of Cambridge; U.K.)
    Acta Metall Sin, 1992, 28 (11): 40-46. 
    Abstract   PDF (2479KB) ( 479 )
    TEM study was made to explore the mechanism of the strain-age hardening of initially-disordered'(Co_(78)Fe_(22))_3V, which was found to be attributed to the formation of a special dislocation-stacking fault configuration in company with disorder-order transformation — dislocations extended to stacking faults on {111} planes and got connected with each other through partial dislocation reaction at intersections of {111} planes, leading to dense networks with cells bounded by stacking fault tetrahedrons. The results also indicated that ordered (Co_(78)Fe_(22))_3V has very low stacking fault energy on {111} planes and relative high and isotropic antiphase boundary energy, which implies that it is most likely to be Lomer-Cottrell locks, not Kear-Wilsdof locks, that are responsible for the high strength at high temperatures of this alloy.
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    MATHEMATICAL SIMULATION ON THREE DIMENSIONAL FLOW IN OFF-CENTER GAS STIRRED BATHS
    LI Baokuan; HE Jicheng; LU Zhongwu (Northeast University of Technology; Shenyang)
    Acta Metall Sin, 1992, 28 (11): 47-53. 
    Abstract   PDF (546KB) ( 498 )
    This paper presents a method which can be used to predict threedimensional flow in gas stirred baths. A kind of general orthogonal curvilinear coordinates was established for calculating the flow in off-center gas stirred baths. Taking the velocity components and pressure as the solution variable, a method to produce the numerical solution of three-dimensional incompressible, steady, time averaged Navier -Stokes equation,continuity equation, k-εtwo equation turbulence model equations under general orthogonal curvilinear coordinates is develeped. The three-dimensional flow in bath can be clearly predicted by this calculation. The velocity vectors calculated for water model is approximately equal to the measured ones.
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    TWO-PHASE EQUILIBRIUM CALCULATION BY THE GRAND POTENTIAL METHOD FOR BINARY ALLOYS
    HAO Shiming; JIANG Min (Northeast University of Technology; Shenyang)
    Acta Metall Sin, 1992, 28 (11): 54-58. 
    Abstract   PDF (317KB) ( 475 )
    A new method for phase equilibrium calculation has been proposed in subregular solution model based on the concept of equality of two-phase equilibrium criterion of both the effective chemical potential and the grand potential. Comparing with the optimization for minimum free energy, it seems to be simpler in calculation and no more convergence problem.
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    NEURON ADAPTIVE ALGORITHM APPLIED TO EXPERIMENTAL DESIGN IN STEEL PRODUCTION
    CONG Peisheng; LI Tonghua (Tongji University; Shanghai) CHEN Yu; CHEN Nianyi (Shanghai Institute of Metallurgy; Academia Sinica; Shanghai)
    Acta Metall Sin, 1992, 28 (11): 59-61. 
    Abstract   PDF (255KB) ( 492 )
    The suitability of neuron algorithm to linear seperatable pattern space was discussed. It was applied to find the optimal condition in production of some alloyed steels. A comparison was made between neuron algorithm and traditional pattern recognition technique. The results show that the neuron algorithm is a simple, reliable algorithm and self adaptive pattern recognition technique.
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    PHASE DIAGRAM OF KF-LiCl-SrCl_2 SYSTEM
    YAN Licheng; XU Jingyan; YANG Jinxiu; DING Yong (Shanghai University of Science and Technology)
    Acta Metall Sin, 1992, 28 (11): 62-64. 
    Abstract   PDF (182KB) ( 548 )
    Phase dingram of KF-LiCl-SrCl2 system has been determined by visual variable-temperature methed. Its functional relation of the parameter of solution energy vs area of rigion of the primary divalent metal fluoride crystal, proposed by the authors previously, has also been discussed.
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    ISOTHERMAL CRYSTALLIZATION KINETICS OF AMORPHOUS (Fe (0.99)Cu_(0.01))_(78)Si_9B_(13) ALLOY
    LIU Xuedong; WANG Jingtang (State Key Laboratory of RSA; Institute of Metal Research; Academia Sinica; Shenyang)
    Acta Metall Sin, 1992, 28 (11): 65-69. 
    Abstract   PDF (620KB) ( 476 )
    Two stages of isothermal crystallization of the amorphous(Fe_(0.99)Cu_(0.01))_(78)Si_9B_(13) alloy were observed under examination by DSC together with XRD and TEM, i.e., precipitation of α-Fe(Si) solution and Fe_2B intermetallic compound. The nucleation and growth of both phases were analyzed based on the concept of local Avrami index and the crystallization "C" curve of the alloy was obtained. Comparison of activation energies of crystallization of both phases indicates that the precipitation of α-Fe(Si) is easier than that of Fe_2B. Meanwhile, an addition of Cu to the FeSiB glass may improve the morphology of α-Fe(Si) particles.
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    MAGNETIC PROPERTIES AND CRYSTALLIZATION OF AMORPHOUS Nd_4Fe_(77.5)(B_(1-x)C_x)_(18.5) ALLOYS
    CAO Lei; SHEN Baogen; YANG Linyuan; ZHAO Jiangao (State Key Laboratory of Magnetism; Institute of Physics; Academia Sinica; Beijing)
    Acta Metall Sin, 1992, 28 (11): 70-74. 
    Abstract   PDF (413KB) ( 472 )
    The ribbons of Nd_4Fe_(77.5)(B_(1-x)C_x)_(18.5) alloys, prepared by melt-spinning method, are still amorphous for x≤0.6 and become crystalline for x≥0.8 after rapid quenching. The effect of C substitution for B on Curie temperature as well as on magnetization and crystallization temperatures of these alloys has been studied. The crystalline phases have also been analyzed in the samples after heat treatment.
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    X-RAY DIFFRACTION STUDY ON CRYSTALLIZATION OF AMORPHOUS Fe (76.5)Cu_1Si_(13.5)B_9 ALLOY
    YANG Huisheng; XIONG Xiaotao; XU Zuxiong; MA Ruzhang (University of Science and Technology Beijing); TU Guochao; ZHANG Jiaji (Institute of Metallurgy; Shoudu Iron and Steel Company)
    Acta Metall Sin, 1992, 28 (11): 75-80. 
    Abstract   PDF (460KB) ( 475 )
    X-ray diffraction peak for α-Fe solid solution (α-phase) precipitates during crystallization of Fe_(76.5)Cu_1Si_(13.5)B_9 amorphous alloy was asymmetrical and dependent on annealing temperature. The fitting results for (200)_α peak indicated that Cu atoms may promote the nucleation of α-phase and dissolve in it so the crystallization has no relation with the as-quenched α phase. The bond energy between atoms in alloy shows that Cu atoms interact slightly with others, as a result, it decreases the removal energy barrier and the crystallization initiates in the Cu-rich region, and results in the decrease of crystallization temperature.
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    COMPARISON OF CRYSTALLIZATION OF METALLIC GLASS Cu_(60)Zr_(40) PREPARED BY DROP-TUBE PROCESSING VS RAPIDLY QUENCHING
    MA Xueming; DONG Yuanda (Institute of Solid State Physics; Academia Sinica; Hefei); WU Jianguo; GUO Weili (Institute of Physics; Academia Sinica; Beijing)
    Acta Metall Sin, 1992, 28 (11): 81-85. 
    Abstract   PDF (387KB) ( 558 )
    Crystallization behaviour of metallic glass Cu_(60)Zr_(40) prepared by drop-tube processing in comparison with that by rapidly quenching has been investigated using X-ray diffraction and DSC thermal analysis. A significant difference between them was found. The precipitated phase Cu_(10)Zr_7 may crystallize out from amorphous ribbon prepared by rapidly quenching by a polymorphous reaction, whersas the primary crystailization mode was occurred in the sample formed by drop-tube processing.
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    DEBONDING AND PULL-OUT OF FIBRE FROM AN ELASTIC MATRIX
    FU Shaoyun; ZhOU Benlian; LONG Qiwei (LUNG Chiwei) (International Centre for Materials Physics; Institute of Metal Research; Academia Sinica; Shenyang)
    Acta Metall Sin, 1992, 28 (11): 86-94. 
    Abstract   PDF (544KB) ( 530 )
    Debonding and pull-out of fibre from an elastic matrix were analysed. The nonlinear functions of initial debonding stress, complete debonding stress as well as pull-out stress of fibre and embedded fibre length were obtained. It has been certified by the existing pull-out test of steel wires from an epoxy matrix. And it has been shown that the initial debonding stress of fibre approaches a constant when the embedded fibre length is comparatively large; the complete debonding stress of fibre increases with the increase in the embedded fibre length and gets to a steady state finally; the pull-out stress of fibre increases with the embedded fibre length.
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