Z. J. Zhan

Chinese Academy of Sciences, Peping, Beijing, China

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Publications (19)29.05 Total impact

  • R. G. Zheng, Z. J. Zhan, W. K. Wang
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    ABSTRACT: A new type Cu–La2O3 composite was fabricated by internal oxidation method using powder metallurgy. Sliding wear behavior of the Cu–La2O3 composites was studied by using a pin-on-disk wear tester under dry sliding conditions with or without electrical current, rubbing against GCr15 type bearing steel disk at a constant sliding speed of 20m/s. The influence of varying applied load and electrical current was investigated. The worn surfaces were examined using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) to determine the wear mechanisms. The results showed the Cu–La2O3 composites had an electrical conductivity of 81.9% IACS (International Annealed Copper Standard, 100% IACS=58MS/m) and a hardness of HV105. The wear rate of the Cu–La2O3 composite pins increased with the increase in the electrical current at high sliding speed. The main wear mechanisms of the Cu–La2O3 composites were found to be adhesive wear, abrasive wear and arc erosion.
    Wear. 01/2010; 268(1):72-76.
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    ABSTRACT: Crystallization of Zr41Ti14Cu12.5Ni10Be22.5 bulk metallic glass (BMG) prepared by shock-wave quenching under high-temperature and high-pressure has been examined by in situ synchrotron radiation x-ray diffraction. The first precipitated phase is found to be the same at different pressures, but the subsequent phase precipitation sequences are different. The crystallization temperature of the BMG increases with pressure, but with a sudden drop at about 6.0 GPa. The different phase precipitation sequences and the sudden drop in the crystallization temperature can be explained by complex pressure effects on the atomic configuration of the BMG.
    Journal of Physics Condensed Matter 11/2007; 20(1):015201. · 2.22 Impact Factor
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    ABSTRACT: Compression behaviour and micro-structure evaluation of Zr57Nb5Cu15.4Ni12.6Al10 bulk metallic glass is investigated at room temperature up to 32.8 GPa using in-situ high pressure energy dispersive X-ray diffraction with a synchrotron radiation source. The equation of state of the bulk metallic glass is −ΔV/V=0.012P−2.49×10−4P2−9.5×10−7P3+5.02×10−8P4. The result shows that the nearest atom pair of the as-quenched bulk metallic glass corresponds to Zr–Zr correlations. And with pressure increasing, the nearest atom pair changes to a new one at 32.8 GPa.
    Materials Letters 05/2007; 61(11):2170-2172. · 2.27 Impact Factor
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    ABSTRACT: A novel fast cooling technology, melt-liquid-quenching (MLQ) with special cooling medium, was invented to prepare Al–7.0wt.%Si–0.4wt.%Mg alloys. The microstructure and mechanical properties of the alloy was investigated by differential scanning calorimetry (DSC), scanning electron microscopy (SEM), microhardness (HV) and tensile strength testing method. The DSC results showed that exothermal peak around 260°C of Al–7%Si–0.4%Mg alloys obtained by MLQ method is broader than that obtained by water-cooling copper mould (WCCM). When the specimens obtained by these two methods were aged at 260°C for 8h, no exothermal peaks were found. This demonstrated that, cooling rate of melt obtained by MLQ method is faster than that obtained by WCCM method. Microstructure of the castings obtained by MLQ was refined obviously and both microhardness and ultimate tensile strength (UTS) of the alloy were 33.3 and 22.9% higher than those made by WCCM, respectively.
    Journal of Materials Processing Technology - J MATER PROCESS TECHNOL. 01/2007; 187:791-793.
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    ABSTRACT: Crystallization of Zr41.9Ti14.7Cu13.1Ni10.1Be20.2 (number indicate at.%) bulk metallic glasses prepared by shock-wave quenching and water-quenching are investigated by in situ X-ray diffraction under continuous heating conditions. Different phases and different precipitation sequences are found for both bulk metallic glasses. The differences in crystallization are probably attributed to different atomic configurations between the two bulk metallic glasses prepared by different ways.
    Materials Science and Engineering A-structural Materials Properties Microstructure and Processing - MATER SCI ENG A-STRUCT MATER. 01/2007; 449:617-620.
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    ABSTRACT: Phase transition cooling (PTC), using the absorbed latent heat during the melting of phase transition cooling medium to cool and solidify alloys in the process of casting, is a new fast cooling technology. Specimens of A356 casting aluminum alloy were prepared by this method. For comparison, specimens made by water-cooling copper mould (WCCM) were prepared too. The mechanical properties of A356 alloy made by PTC and WCCM were measured by microhardness and tensile strength testing methods. Microstructures of A356 alloy were investigated by scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and X-rays diffraction (XRD). The results show that both microhardness and ultimate tensile strength (UTS) of A356 alloy made by PTC method are much higher than those made by WCCM method. This can be attributed to the refined microstructure and the extended solubility of silicon in α-Al. The solubility of silicon in α-Al was 2.7at.% in specimens solidified in phase transition cooling medium and 2.4at.% in specimens solidified in water-cooling copper mould.
    Materials Science and Engineering A-structural Materials Properties Microstructure and Processing - MATER SCI ENG A-STRUCT MATER. 01/2007; 448(1):361-365.
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    ABSTRACT: High speed impact on Zr41Ti14Cu12.5Ni10Be22.5 bulk metallic glass (BMG) was realized by a two-stage light gas gun. Under planar shock wave at the impact velocity of 2.7 km/s, radial symmetric cracks formed on the shocked surface of the sample. Shear cracks/bands about 35° to the shocking direction and parallel to each other on the cross-section of the recovered sample were found in the layer subjacent to the shocked surface. Obvious traces of melting were shown inside the adiabatic shear cracks. Under spherical shock wave, crater profiles and lamination cracks were presented in addition to the adiabatic shear cracks/bands. The cracking of the BMG follows a process of nucleation, growth, and coalescence of micro-voids.
    Materials Science and Engineering: A. 06/2006; 426(s 1–2):298–304.
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    ABSTRACT: Crystallization of Zr41Ti14Cu12.5Ni10Be22.5 bulk metallic glass under high temperature and high pressure has been investigated by in situ synchrotron radiation x-ray diffraction. The onset temperature of crystallization was found to increase with pressure, but with a sudden drop at about 5.6 GPa. Though the primarily precipitated phase is the same at different pressures, the sequences of the following phase precipitation are different.
    Journal of Applied Physics 01/2006; 99(2). · 2.21 Impact Factor
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    ABSTRACT: Planar shock compression effects on void formation and cracking in Zr41Ti14Cu12.5Ni10Be22.5 bulk metallic glass (BMG) are studied in this paper. Cracking was found to be a result of void linkage in some direction deviation from the maximum shear stress plane. Changing the state of the stress inside the BMG sample led to formation of different void distribution. Nucleation of the microvoids was possibly initiated by release of excess free volume under shock wave compression.
    Journal of Materials Science 07/2005; 40(15):3917-3920. · 2.31 Impact Factor
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    ABSTRACT: Zr41Ti14Cu12.5Ni10Be22.5 bulk metallic glass (BMG) was prepared by shock-wave quenching. Differences in property, structure, and thermal stability were found between the BMGs prepared by the shock-wave quenching and water quenching. The glass transition temperature of the shock-wave-quenched BMG is about 13 K higher than that of the water-quenched one. Although the density of the shock-wave-quenched BMG is decreased, the acoustic velocities in it are increased. Shock-wave quenching is possibly a promising method for preparing BMG.
    Applied Physics Letters 07/2005; 87(5):051904-051904-3. · 3.52 Impact Factor
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    ABSTRACT: Structural changes in bulk metallic Zr41.2Ti13.8Cu12.5Ni10Be22.5 glass subjected to heat treatments under high pressure were investigated by means of synchrotron radiation x-ray diffraction (SRXRD). In situ SRXRD measurements showed that the crystallization process of this material is comprised of two stages. Subsequent heating at 10 GPa converts the sample from the amorphous (Am) phase into a metastable fcc phase and then leads to the fcc phase changing back to the Am phase, indicating that there is a kind of 'reversible' phase transition phenomenon occurring in the alloy. Such phenomenon is explained on the basis of free energy considerations.
    Journal of Physics Condensed Matter 10/2002; 14(44):11243. · 2.22 Impact Factor
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    ABSTRACT: The wear behavior of bulk Zr41Ti14Cu12.5Ni10Be22.5 metallic glasses has been studied using sliding wear tests and scanning electron microscopy in both as-prepared and annealed samples. It was found that the wear resistance of differently processed samples increases in the following order: crystallized state; as-prepared state; relaxed state. The thermal stability of worn samples was also investigated by meansof differential scanning calorimetry. Under the experiment conditions, no sliding wear-induced crystallization is observed in either as-prepared or relaxed samples indicating good thermal stability of the bulk metallic glasses.
    Journal of materials research 05/2002; 17(8):1877. · 1.67 Impact Factor
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    ABSTRACT: The wear behavior of bulk Zr41Ti14Cu12.5Ni10Be22.5 metallic glasses has been studiedusing sliding wear tests and scanning electron microscopy in both as-prepared and annealed samples. It was found that the wear resistance of differently processed samples increases in the following order: crystallized state; as-prepared state; relaxed state. The thermal stability of worn samples was also investigated by means of differential scanning calorimetry. Under the experiment conditions, no sliding wear-induced crystallization is observed in either as-prepared or relaxed samples indicating good thermal stability of the bulk metallic glasses.
    Journal of Materials Research - J MATER RES. 01/2002; 17(8):1877-1880.
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    ABSTRACT: The compression behaviour of a Pd39Ni10Cu30P21 bulk metallic glass is investigated at room temperature up to 23.5 GPa using in situ high pressure energy dispersive x-ray diffraction with a synchrotron radiation source. Pressure induced structural relaxation of the bulk metallic glass is exhibited within the pressure range. It is found that below about 5 GPa, the existence of excess free volume contributes to rapid structural relaxation, which gives rise to rapid volumetric change. Under higher pressure, further relaxation results
    Journal of Physics Condensed Matter 04/2001; 13:5743. · 2.22 Impact Factor
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    ABSTRACT: The compression behaviour of a Pd 39 Ni 10 Cu 30 P 21 bulk metallic glass is investigated at room temperature up to 23.5 GPa using in situ high pressure energy dispersive x-ray diffraction with a synchrotron radiation source. Pressure induced structural relaxation of the bulk metallic glass is exhibited within the pressure range. It is found that below about 5 GPa, the existence of excess free volume contributes to rapid structural relaxation, which gives rise to rapid volumetric change. Under higher pressure, further relaxation results in structural stiffness.
    Journal of Physics Condensed Matter 01/2001; 13:5743-5748. · 2.22 Impact Factor
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    ABSTRACT: Structural relaxations of a Pd39Ni10Cu30P21 bulk metallic glass (BMG) under ambient pressure and at a high pressure are compared by means of temperature-modulated differential scanning calorimetry (TMDSC) measurements. The structural relaxation is evaluated by the enthalpy recovery involved upon passing through the glass transition in the irreversible TMDSC curves. It is found that the isothermal relaxation of the BMG under ambient pressure leads to a lower-enthalpy state than that under a high pressure. The onset temperature for the enthalpy recovery process is found to exhibit a linear dependence on the recovery enthalpy.
    Philosophical Magazine Letters 01/2001; 81(6). · 1.16 Impact Factor
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    ABSTRACT: Acoustic velocities of Pd39Ni10Cu30P21 bulk metallic glass ~BMG! are measured by an ultrasonic technique upon annealing. The elastic constants and the Debye temperature are obtained. A large softening of the transverse phonon is exhibited in the as-quenched BMG relative to its crystallized state. Upon crystallization, the shear modulus and the Debye temperature increase by ;30% and ;12%, respectively; however, the density increases by only ;0.6%. Some anomalous acoustic and elastic behaviors are observed near the glass transition temperature and in the supercooled liquid region of the BMG. The anomalies are explained with regard to the structural changes.
    Applied Physics Letters 01/2001; 77:1147. · 3.52 Impact Factor
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    ABSTRACT: The pressure-dependent acoustic velocities of a Pd39Ni10Cu30P21 bulk metallic glass ~BMG! have been measured up to 0.5 GPa by using an ultrasonic technique with the pulse echo overlap method. The elastic constants, the Debye temperature, and their pressure dependence are obtained. The isothermal equation of state ~EOS! of the BMG is established in terms of the Murnaghan form. The atomic configurations of the BMG are discussed by comparing the elastic constants and the EOS with those of its metallic component and of other amorphous materials.
    Applied Physics Letters 01/2000; 77:3734. · 3.52 Impact Factor
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    ABSTRACT: Journal article
    J. Appl. Phys. 99(2006),023525.

Publication Stats

62 Citations
29.05 Total Impact Points

Institutions

  • 2000–2006
    • Chinese Academy of Sciences
      • • Institute of Physics
      • • Condensed Matter Physics
      Peping, Beijing, China
  • 2002
    • Northeast Institute of Geography and Agroecology
      • Key Laboratory of Extreme Conditions Physics
      Beijing, Beijing Shi, China