2018年, 第25卷, 第6期　刊出日期：2018-06-15

  

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  Deformation behavior of Ta wire-reinforced Zr-based bulk metallic glass composites

  Sen Chen,. Hua-meng Fu, . Zheng-kun Li . Long Zhang . Hong-wei Zhang, . Zheng-wang Zhu . Hong Li . Ai-min Wang . Yan-dong Wang . Hai-feng Zhang,

  . 2018, 25(6): 601-607.

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  Abstract: A Ta wire-reinforced Zr-based bulk metallic glass composite with a new type of structure was prepared successfully by the method of liquid metal in.ltration. Ta wires distribute uniformly in the metallic glass matrix in the form of spirals. The composite exhibits two yield stages under compressive stress, and the samples are compressed into thin pancakes. The micro-cracks originate at the interface between the Ta wire and the metallic glass matrix and propagate perpendicularly to the interface, which then induce multiple shear bands in the metallic glass matrix due to the stress concentration. Shear cracks form in the metallic glass matrix during the continued loading process as a result of the interaction of shear bands. Deformation bands of Ta wires occur under the impact of shear bands. The local stress .elds in the composite are changed obviously due to the introduction of the spiral-formed reinforcements. The investigation of the deformation behavior and mechanism suggests a new method for the application of bulk metallic glass composites as the structural materials.
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  Fe-based multi-phase nanocrystalline ribbons with hierarchically flowerlike structured metal oxides after modified by Orange II for CrVI absorption

  Shuang-qin Chen . Liang-zhengDong . Ke-zhen Hui . Zhen Peng . Zhun Li . Zhi-Chao Lu . Yang Shao . Ke-fu Yao

  . 2018, 25(6): 608-613.

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  Abstract: Three-dimensional .owerlike nanostructured metal oxides attached on the surfaces of Fe-based multi-phase nanocrys-talline ribbons (Fe-MNRs) were prepared by a simple way (through immersing the Fe-MNRs in Orange II solution). It has been found that the as-prepared Fe-MNRs with 3D .owerlike nanostructures (Fe-MNRs ? FNs) exhibit good absorption property for a typical heavy metal ion (CrVI) in wastewater, while Fe-MNRs do not possess such properties. The Fe-MNRs ? FNs could remove 99% CrVI ions from the solution in 40 min, and this adsorption property can be attributed to the ion exchange between CrVI and surface hydroxyl groups (O–H) of 3D .owerlike nanostructures. The present result suggests that the Fe-MNRs ? FNs, prepared by facile way, possess great potentials in removing heavy metallic ions in wastewater.
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  Microstructure and magnetic properties of Fe81.3Si4B13Cu1.7 nanocrystalline alloys with minor Nb addition

  Xiang-cheng Ren . Yan-hui Li . Xing-jie Jia . Zhi-yong Qiu . Guo-qiang Xie . Wei Zhang

  . 2018, 25(6): 614-618.

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  The amorphous matrix containing dispersive high number density (Nd) α-Fe nuclei with average grain sizes (D) of 4.3–6.2 nm were formed in the melt-spun Fe81.3-xSi4B13Cu1.7Nbx (x = 0–2) alloys, and the Nd and D values reduce with increasing the Nb content. The fine nanocrystalline structure with α-Fe grains in size of 14.0–21.6 nm was obtained for the alloys after annealing, which show high saturation magnetic flux density of 1.60–1.77 T and low coercivity (Hc) of 7.1–16.2 A/m. Addition of minor Nb significantly expands the optimum annealing temperature range for obtaining low Hc, while coarsens the α-Fe grains, leading to a slight increase in the Hc. The mechanism for the effect of Cu and Nb elements on the structure and magnetic properties was discussed in terms of the formation and growth of the α-Fe nuclei of the alloys.
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  Tuning magnetocaloric effect of Gd–Er–Al–Co metallic glass through crystallization

  Qiang Luo . Jun Shen

  . 2018, 25(6): 619-623.

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  Abstract: Magnetization and magnetocaloric effect (MCE) of as-cast Gd-based bulk metallic glass (BMG) Gd24Er32Co24Al20 and the crystallized samples were investigated. Reentrant-spin-glass-like behavior was observed in the as-cast sample. With increasing degree of crystallization, the magnetic frustration increased, which could be seen from the increased divergence of the zero-.eld-cooled and .eld-cooled magnetization behavior (i.e., the spin-glass-like freezing behavior). The Curie temperature and magnetization decreased after crystallization. The as-cast BMG showed a large maximum magnetic entropy change (-DSm)of9.9(J kg -1K -1) under a .eld change of 5 T, which was comparable with that of Gd metal and other Gd-based metallic glasses. The maximum -DSm reduced to 6.7 (J kg -1K -1) after crystallization, which was still superior to the Fe-/Co-based amorphous alloys. Their good MCE combining with high electrical resistivity, outstanding mechanical properties, tunable nature, and suf.ciently soft magnetic property makes them to be attractive candidate for magnetic refrigerants in the low-temperature range.
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  Controllable SiO2 coating layer of FeSiBPNb amorphous powder cores with excellent soft magnetic properties

  Ke-yu Huang, . Ya-qiang Dong . Min Liu . Ji-hang Ren . Shu-han Lu . Zhan-kui Zhao . Chun-tao Chang . Xin-min Wang

  . 2018, 25(6): 624-629.

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  Abstract: Amorphous powder cores based on spherical (Fe0.76Si0.09B0.1P0.05)99Nb1 amorphous powder and their SiO2 layer prepared by in situ coating insulation process were investigated in detail. These cores were characterized by scanning electron microscopy and X-ray diffraction analyses, and the results revealed that the surface layer of the amorphous powder was composed of SiO2 with uniform surface coverage. The thickness of the SiO2 insulating layer could be controlled by adjusting the tetraethyl orthosilicate (TEOS) content. By cold-pressing with epoxy resin under a pressure of 1800 MPa, a ring powder core with an outer diameter of 20.3 mm, inner diameter of 12.7 mm, and height of 5.3 mm was prepared. The FeSiBPNb composite core showed its best properties when the TEOS content was 2 mL/g (the volume of TEOS for each gram of (Fe0.76Si0.09B0.1P0.05)99Nb1 amorphous powder, mL/g), which showed good relative permeability in the high-frequency range of up to 10 MHz and a low core loss of 320 W/kg under the maximum magnetic .ux density of 0.1 T and frequency of 100 kHz.
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  Effects of casting current on structure and properties of a nanostructured Zr–Cu–Fe–Al bulk metallic glass

  Si-nan Liu .Wei-xiaDong . Chen-yu Lu . Zhu-wei Lu . Jia-cheng Ge . Chen-chen Yuan . Bao-an Sun . Tao Feng . Xun-li Wang . Si Lan

  . 2018, 25(6): 630-636.

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  In this paper, we studied the effects of casting currents on the thermophysical behaviors, atomic and nanoscale structure, and mechanical properties of two Zr-based-bulk metallic glasses, i.e.Zr59Cu33Al8 and Zr59(Cu0.55Fe0.45)33Al8, using differential scanning calorimetry,wide-angle X-ray diffraction, and small-angle X-ray scattering, as well as compression tests. Our results revealed that there is no anomalous structural change for the Zr59Cu33Al8 molten liquid before crystallization during cooling with different casting currents. In contrast, a liquid-state phase separation was suggested to occur in the Zr59(Cu0.55Fe0.45)33Al8 molten liquid prepared using lower casting current before crystallization during cooling. The position shift of the first sharp diffraction peak for the diffraction pattern of Zr59(Cu0.55Fe0.45)33Al8 shows that the density of the molten liquid may decrease upon cooling at different casting currents. The small-angle X-ray scattering results indicate that the heterogeneity of the Zr59(Cu0.55Fe0.45)33Al8 metallic glasses increases with the decreasing of the casting temperature. As a result, the metallic glasses with a liquid-state phase separation possess better mechanical properties, including higher-yielding stress and more significant compressive ductility. The increasing of loosely packed regions formed by liquid-state phase separation and their interactions with the shear bands for the Zr-Cu-Fe-Al BMGs were suggested to be responsible for the enhanced compressive plasticity.Our results may shed light on research and development of nanostructured bulk metallic glasses with tunable structures and plasticity.
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  Asynchronous responses of mechanical and magnetic properties to structure relaxation for FeNbB bulk metallic glass

  Zhi-kai Gao, . An-ding Wang,, . Ping-bo Chen . Cheng-liang Zhao, . Fu-shan Li . Ai-na He, . Chun-tao Chang, . Xin-min Wang, . Chain-tsuan Liu

  . 2018, 25(6): 637-643.

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  Abstract: Asynchronous responses of mechanical and magnetic properties to structure relaxation for the Fe71Nb6B23 bulk metallic glass were systematically investigated. It is interesting that this ternary alloy can combinedly exhibit outstanding magnetic and mechanical properties, especially good ductility, after optimally annealing in structure relaxation stage for eliminating the internal stress and homogenizing the microstructure. The alloy exhibits low coercive force of 1.6 A/m, high effective permeability of 15 9 103, high fracture strength of 4.2 GPa and good plastic strain of 1.8%. It is also found that responses of mechanical and magnetic properties to structure relaxation are asynchronous. The glass transition and crystallization will greatly deteriorate the magnetic and mechanical properties. Here we propose a physical picture and demonstrate that the primary structure factors determining magnetic and mechanical properties are different. This work will bring a promising material for application and a new perspective to study the effect of annealing-induced structure relaxation on mechanical and magnetic properties.
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  Zr55.8Al19.4(Co12xCux)24.8 (x = 0–0.8 at.%) bulk metallic glasses for surgical devices applications

  Kai-ming Han . Jian-bing Qiang . Ying-min Wang . Bing-bing Zhao .PeterHa¨ussler

  . 2018, 25(6): 644-649.

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  Abstract: Zr–Al–Co–Cu bulk metallic glasses (BMGs) are promising surgical materials. By using the electron concentration criterion for BMG composition design, a series of Zr55.8Al19.4(Co1-xCux)24.8 (x = 0–0.8 at.%) alloys were produced, of which BMG rod samples with different diameters were made by copper mold casting. Among these alloys, the Zr55.8Al19.4Co17.36Cu7.44 BMG exhibited a centimeter-scale glass formation size (dmax = 12 mm), an ultrahigh strength (ry = 2.04 GPa), a large room-temperature plasticity (ep = 4.0%), and a fracture toughness (KQ = 120 MPa m1/2), as well as good corrosion resistance in phosphate-buffered solution. The attainment of the combination of properties as large glass-forming ability with excellent mechanical and corrosion stability would suit the surgical devices applications.
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  Effects of Ti addition on corrosion behavior of Zr-based metallic glass in chloride medium

  Zhang-wei-jia Qiu, . Hua-meng Fu, . Hong-wei Zhang, . Hong Li . Zheng-kun Li . Long Zhang . Zheng-wang Zhu . Ai-min Wang . Hai-feng Zhang

  . 2018, 25(6): 650-657.

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  To improve the corrosion resistance of Zr51.3Al10Ni6Cu31.8Ag0.1Y0.8 metallic glass in acid chloride solution, Ti was added into the alloy. XRD results show these Ti-added alloys with diameters of 3 mm are all metallic glasses. Weight loss and electrochemical method were introduced to characterize their corrosion resistance. Results show that the corrosion resistance of metallic glass is significantly improved with Ti addition. XPS study demonstrates that Zr dioxides dominate in passive film during corrosion when Ti content is low. High-content Ti addition can lead to an evident accumulation of Ti dioxides, this accumulation results in a thicker, Ti-enriched protective passive film.
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  Correlation between mechanical and thermodynamic properties for La–Ce–Ni–Cu–Al high-entropy metallic glasses

  Lin Wu . Yong Zhao . Jun-jun Li . Ji-li Wu . Bo Zhang

  . 2018, 25(6): 658-665.

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  Abstract: The mechanical properties, thermodynamic features and their correlation were studied for La–Ce–Ni–Cu–Al high-entropy bulk metallic glasses (HE-BMGs). Compressive testing indicated that the HE-BMGs are ductile on a microscopic scale but brittle on a macroscopic scale, because of the low fragility index m of the HE-BMGs. In the non-isothermal process, the activation energies for glass transition for these HE-BMGs are the lowest of the known HE-BMGs. Large values of the Avrami exponent n imply that the crystallization process proceeded through three-dimensional growth and with an increasing nucleation rate. The activation energy for glass transition (Eg) is almost proportional to the HE-BMG fracture strength, because a higher Eg is required to dislodge the molecules from the glassy con.guration for the HE-BMGs with a high strength. The .ndings provide unambiguous evidence for the correlation between the mechanical and thermodynamic properties.
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  Effects of pressure on structure and dynamics of metallic glass-forming liquid with miscibility gap

  Yun Cheng . Peng-fei Wang . Chuan-xiao Peng . Li-jing Jia . Yu-yang Wang . Li Wang

  . 2018, 25(6): 666-673.

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  Abstract: The metallic liquid with miscibility gap has been widely explored recently because of the increasing plastic deformation ability of phase-separated metallic glass. However, the poor glass-forming ability limits its application as the structural materials due to the positive mixing enthalpy of the two elements. Since high pressure is in favor of the formation of the glass, the effect of pressure on the structural and dynamical heterogeneity of phase-separated Cu50Ag50 liquid is inves-tigated by molecular dynamics simulation in the pressure range of 0–16 GPa. The results clearly show that the pressure promotes the formation of metallic glass by increasing the number of .vefold symmetry cluster W and dynamical relaxation time; meanwhile, the liquid–liquid phase separation is also enhanced, and the homogenous atom pairs show stronger interaction than heterogeneous atom pairs with increasing pressure. The dynamical heterogeneity is related to the formation of .vefold symmetry clusters. The lower growing rate of W at higher pressure with decreasing temperature corresponds to the slow increase in dynamical heterogeneity. The pressured glass with miscibility gap may act as a candidate glass with improved plastic formation ability. The results explore the structural and dynamical heterogeneity of phase-separated liquid at atomic level.
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  Influences of preparation techniques on glass-forming ability of Fe–P– B–Si–C amorphous alloys

  Ji-jun Zhang,,, . Ya-qiang Dong, . Lu-yang Bie . Qiang Li . Jia-wei Li, . Xin-min Wang,

  . 2018, 25(6): 674-679.

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  It has widely been accepted that the ultrahigh cooling rate is required for the glass formation of amorphous alloys. Here, the larger glass forming ability (GFA) of Fe76P5(B0.5Si0.3C0.2)19 amorphous alloy is achieved by water quenching at lower cooling rate under argon atmosphere. Cylindrical rods with diameters of 1 to 2 mm are prepared by water quenching without flux treatment, Cu-mold injection casting, and Cu-mold suction casting, respectively. The influences of the preparation techniques with different cooling rates on GFA, thermal property, and nucleation/growth behavior are examined. The critical diameter of the Fe76P5(B0.5Si0.3C0.2)19 amorphous alloys is 1.7 mm for water quenching while smaller than 1 mm for injection casting. Microstructure analysis indicates that the crystallization and solidification processes are quite different between the water-quenched and the injection casted rods. This finding provides fundamental understanding on the relationship between the cooling rate, techniques, and GFA of Fe-based amorphous alloys.