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Abstract: The effects of casting temperature on microstructure and mechanical properties of as-cast 3mm-diameter Zr64.9Al7.9Ni10.7Cu16.5 and Zr47Cu37.5Ag7.5Al8 alloys were investigated. It was found that crystalline phases were precipitated in amorphous matrix as casting temperature increased. The compressive strength and Hv of as-cast Zr64.9Al7.9Ni10.7Cu16.5 and Zr47Cu37.5Ag7.5Al8 alloys increased slightly when casting temperature increased. However, ultrahigh casting temperature resulted in formation of hard crystalline phase in metallic glass matrix, which caused increase of hardness and density, but decrease of compressive strength. [Copyright &y& Elsevier]

An Al-based metallic glass rod with 0.75 mm diameter was prepared successfully using the copper-mould casting technique together with the proper melt treatment of the liquid alloy. The compressive properties of this Al-Ni-Y metallic glass were experimentally examined. The results showed that the amorphous alloy has a high yield strength of 1090 MPa and a compressive fracture strength of 1150 MPa. Its fracture surface presented typical vein patterns and melting phenomena characteristic of a monolithic metallic glass. [ABSTRACT FROM AUTHOR]

Abstract: Bulk metallic glasses (BMGs) with high thermal stability, good mechanical properties and high corrosion resistance were synthesized in the Ni–Nb–Zr system. A large bulk glass-forming region with 60

Abstract: Alumina ceramics are stable materials in contact with metallic melts and bulk metallic glasses (BMGs) may be used as metal–matrix composites (MMCs). In this study, the wetting behavior and metal-oxide interfaces in the CuZr-based BMGs/alumina system were investigated by the sessile drop method in a high vacuum furnace. It was found that Cu50Zr50, Cu45Zr48Al7 and Cu40Zr44Al8Ag8 BMG presented final equilibrium contact angle values around 43°, 13° and 2° at respective temperature of melting point. The samples were cut transversaly and characterized by scanning electron microscopy (SEM) and electronic probe microscopic analyzer (EPMA). The interface was continuous and no intermediate reaction layer was formed at the interface of CuZr-based BMGs/alumina. However, diffusion band was observed at the fringe of metallic drop. [Copyright &y& Elsevier]

Abstract: A densely packed striation structure is observed in the apparently featureless mirror area of the fracture surface of brittle Mg-based bulk metallic glass. Taylor instability analysis based on grease model combined with a competitive microvoid formation mechanism ahead of a blunted crack tip suggests that the fracture of metallic glass is controlled by both viscous flow and ductile fracture mechanism. Spacing size of the striation is correlated with macroscopic fracture toughness. [Copyright &y& Elsevier]

Abstract: Bulk metallic glasses (BMGs) Fe56Co7M2Zr10Mo5B20 (M=W or Ni) with diameters of 1.5mm were fabricated by copper mould casting method. There is no significant difference in the glass properties such as glass transition temperature (T g), onset temperature of crystallization (T x ), supercooled liquid region (ΔT x ), and offset temperature of melting (T l) except that the onset melting temperature T m, which are 1454 and 1464K for the alloy containing W and Ni, respectively. The alloy containing W exhibits some paramagnetic properties while the Ni containing alloy shows fully ferromagnetic. The potentiodynamic polarization experiments show that these alloys have a high corrosion resistance in 3.5% NaCl solution with strong passivation ability. The alloy containing W shows excellent pitting resistance with a wide passive range (ΔE =852mV) and low passive current density in the order of μAm−2. Electrochemical impedance spectroscopy (EIS) for either alloy consists only of single capacitive loop. [Copyright &y& Elsevier]

The bulk amorphous alloy Ni45Ti23Zr15Si5Pd12 has been prepared by copper mold casting. The crystallization kinetics of the alloy has been investigated using differential scanning calorimetry by means of continuous heating and isothermal annealing, and the products of crystallization have been analyzed by transmission electron microscopy and X-ray diffraction. The isothermal activation energy obtained from Arrhenius equation increases in the process of crystallization transformation. The details of nucleation and growth during the isothermal crystallization are expatiated in terms of local Avrami exponent and local activation energy. Meanwhile, the origins of nanocrystal formation during the annealing process have also been discussed. [Copyright &y& Elsevier]

Based on the embedded-atom method, a constant-pressure, constant-temperature molecular dynamics technique is applied to obtain an atomic description of glass formation process in eutectic Cu40Ag60 alloy. By using radial distribution function and pair analysis methods, the structure and glass forming ability of this alloy is studied by quenching from the liquid at different cooling rates (1×1011, 1×1012, 5×1012, 1×1013 and 1×1014 K/s). It is observed that the retention of amorphous structure requires extremely high cooling rates. Structure analyses of the alloys in the simulations reveal the evolvement of the different clusters at various quenching rate during the quenching process. [Copyright &y& Elsevier]

A Mg–30 wt% TiMn1.5 hydrogen storage composite was successfully synthesized by mechanical milling of a mixture of magnesium powder and amorphous TiMn1.5 powder. The absorption/desorption rates and storage capacity under different temperatures were evaluated. The composite possesses high hydrogen storage capacity and exhibits excellent absorption/desorption kinetic properties and is activated in situ due to reaction ball milling (RBM). The hydrogen capacity is over 2.7 wt% at 373 K, and one absorption/desorption hydrogen cycle can be finished in 20 min at 523–573 K. Interestingly, the desorption temperature begins at about 500 K, decreasing about 40 K in contrast to that of the milled pure MgH2. Mechanical milling produces fine powder with nanometer-scaled grains and introduces many imperfections into the Mg matrix, which contribute to the enhanced hydrogen absorption/desorption rates with high capacity catalyzed by TiMn1.5 (amorphous). [Copyright &y& Elsevier]

Abstract: Using the sessile-drop method, the wettability and diffusion of the molten Bi–Sn on amorphous and crystalline Fe78B13Si9 alloy are studied at isothermal condition, and the interfacial characteristics were investigated by HRSEM and EPMA. The results show that the contact angle of Bi–Sn alloy melts on amorphous substrate is smaller than that of Bi–Sn alloy melts on the crystalline one at 423 K. The interface is continuous, while no intermediate reaction layer formed at the interface of molten Bi–Sn on amorphous and crystalline Fe78B13Si9, respectively. The width of diffusion layer of Bi–Sn alloy melts on the amorphous substrate is thinner than that on the crystalline one under identical conditions. [Copyright &y& Elsevier]

Abstract: We successfully fabricated nanocrystalline (NC) indium (In) particles embedded in Al-based amorphous matrix. Systematic investigations indicate that thermal interaction between the NC In and the amorphous matrix significantly influences their respective thermal behaviors. The melting temperature of NC In was found to be depressed by 10–30K, owing to the specific interfacial structure of NC In/amorphous system. The simultaneous appearance of the liquid/amorphous interface destabilizes the amorphous matrix, leading to face-centered cubic-Al precipitation at the interface of In sphere/amorphous matrix at a relatively lower temperature. This effect is attributed to the diffusion of La from the matrix to the liquid In particles. [ABSTRACT FROM AUTHOR]

Abstract: A new bulk metallic glass (BMG) Fe60B15Zr10Co7Mo5.5Y2Si0.5 was synthesized by Cu mold casting. The alloy was characterized by X-ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS) techniques. The thermal stability and glass-forming ability (GFA) of the alloy have been discussed by evaluating a number of thermal parameters. The maximum values of the key thermal parameters like T rg (T g/T m, T g/T l), γ, δ and β parameters were found to be ∼(0.66,0.64), 0.407, 1.84 and 3.83, respectively. The alloy showed double stage crystallization process. The activation energies for crystallization were found to be 606.6 and 623.1kJ/mol by Kissinger and Ozawa equations, which indicate the high thermal stability. Crystallization behavior of the alloy was explored by XRD. Mechanical properties like Vicker’s hardness, nanohardness and elastic modulus are found to be very promising. [Copyright &y& Elsevier]

A new Cu-based bulk metallic glass of 10mm diameter was successfully prepared by a conventional copper mold casting method using alloy Cu46Zr45Al7Gd2. The addition of Gd effectively alleviates the harmful effects of oxygen in the melt by the preferential formation of gadolinium oxide and significantly increases the glass-forming ability. The T rg = T g/T m reaches a maximum value of 0.694 for the Cu46Zr45Al7Gd2 alloy, which is consistent with the experimental results. [Copyright &y& Elsevier]

Abstract: Cu-based bulk metallic glass (BMG) composites containing in situ TiB particles were successfully fabricated. The reinforcing TiB particles with a size of 5–10μm are uniformly distributed in the amorphous matrix. The particles have a good bonding to the matrix with a reaction layer. The BMG composites exhibit an obvious ductility with a plastic strain of 2% for the 17.5vol.% TiB sample due to the suppression of shear band propagation and the generation of multiple shear bands during compressive testing. The hardness of the materials is increased from Hv543 for monolithic BMG to Hv650 for 23.6vol.% TiB-containing BMG composite. [Copyright &y& Elsevier]

A new bulk metallic glass Fe56Co7Ni2Zr10Mo5B20 rod with a diameter of 1.5 mm was prepared by copper mould casting from industrial raw materials. The amorphous state and crystallization behaviour were investigated by X-ray diffraction. The thermal stability, such as the glass transition temperature (Tg), the onset temperature of crystallization (Tx), supercooled liquid region (ΔTx) between Tg and Tx, and reduced glass temperature Trg(Tg/Tm), the ratio of the glass transition temperature (Tg) and the onset temperature of melting (Tm) were measured by differential scanning calorimetry to be 868, 937, 69 K and 0.596, respectively. The crystallization products are determined to be α-Fe, ZrFe2, Fe3B, MoB2, and Mo2FeB2 and an unknown phase, as determined by X-ray analysis of the sample annealed for 1.5 ks at 973 K. This bulk metallic alloy exhibits ferromagnetic properties with saturation magnetization (Ms) of 41.6 emu/g, and low coercivity for the as-cast rod of 1.5 mm diameter. [Copyright &y& Elsevier]

Highlights: [•] The wide-temperature tensile tests of W/Zr interpenetrating composites were reported. [•] It shows evident “work hardening” and excellent properties after tensile test. [•] The results show that it can be employed to forming under high temperature. [Copyright &y& Elsevier]

Abstract: Amorphous coatings with a composition of Fe48Cr15Mo14C15B6Y2 were prepared by means of high velocity oxygen fuel (HVOF) thermal spraying under different conditions. Microstructural studies show that the coatings present dense layered structure and low porosity with a fraction of nanocrystals precipitated. The porosity and amorphous fraction of the coatings decrease as the kerosene and oxygen flow increase within the parameter range examined. Corrosion behavior of the amorphous coatings was investigated by electrochemical measurement. The results show that the coatings are spontaneously passivated with wide passive region and low passive current density in 3.5% NaCl, 1N HCl and 1N H2SO4 solutions, and exhibit an excellent ability to resist localized corrosion. However, the corrosion resistance of the coatings decreases in 1N NaOH solution with lower transpassive potential and passive region. In addition, the optimal spraying parameter improves the corrosion resistance of the amorphous coatings obviously due to the proper proportion of porosity and amorphous fraction. [Copyright &y& Elsevier]

Abstract: Hydrostatic extrusion of a Zr38Ti17Cu10.5Co12Be22.5 bulk metallic glass/porous tungsten phase composite was performed, and the dynamic compressive deformation and fracture behavior of the as-extruded composite were investigated in detail at room temperature by means of the Split Hopkinson Pressure Bar (SHPB). In comparison with the as-cast composite, the as-extruded composite presented a much higher flow stress without sacrificing plasticity under dynamic compression, exhibiting ductility increment, but evidence of work softening was observed. The specimen for the as-extruded composite failed by axial splitting with occasional shear fracture in some regions. It is suggested that the increase in flow stress and ductility of the as-extruded composite is attributed to the extrusion process which introduced hardened condition and texture in the tungsten phase as well as the 3D net structure of the porous tungsten phase. The work softening mechanism appears to be essentially associated with the large number of microcracks and voids under dynamic compression. [Copyright &y& Elsevier]

Abstract: The uniaxial compressive behavior of Zr38Ti17Cu10.5Co12Be22.5 bulk metallic glass was investigated over a wide strain rate range between 10−4 and 102 s−1 at room temperature. Fracture stress as well as strain was found to decrease with increasing strain rate. Specimens subjected to quasistatic loading developed mature shear bands and substantial plastic deformations, fracture surfaces were relatively smooth and revealed a well developed and uniformly distributed mixture of vein-like patterns and river-like patterns. The dynamically loaded specimens, on the other hand, fractured along one dominant shear band with relatively rough fracture surfaces, such as non-uniformly distributed vein-like patterns, micro shear bands, microcracks and liquid droplets. The experimental results demonstrate that the fracture behavior of the present bulk metallic glass is strongly affected by the strain rate. A negative strain rate sensitivity was found and discussed in detail. [Copyright &y& Elsevier]

Abstract: Synthesis of bulk metallic glasses (BMGs) has been one of the hottest topics of research in materials science during this decade due to their very attractive physical and mechanical properties. In the present study, Zr64.5Ni15.5Al11.5Cu8.5 alloy has been synthesized from pure elements using Cu mold-casting technique. The alloy was designed to have e/a ratio=1.3975 and average atomic size R a =0.1500nm. Thermal properties were measured by performing DSC and supercooled liquid region ΔT x was found to be 94.9K. Mechanical properties like microhardness, nanohardness, elastic modulus and fracture strength were measured. The fracture strength was found to be ∼1988MPa. SEM examination shows vein-like patterns in the fractured compression-tested samples. Shear bands were observed and shear angle was found to be ∼36±1° which is 6° less than that for most of the bulk metallic glasses to date without addition of fifth element. [Copyright &y& Elsevier]

Abstract: As-cast bulk and as-spun ribbon Cu60Zr30Ti10 metallic glasses were characterized using differential-scanning calorimetry and instrumented nanoindentation. Two alloys show a significant difference in the amount of free volume, which is attributed to the difference in a cooling rate, while exhibiting a similar serrated plastic flow. Atomic-force-microscopy observations demonstrate the pile-ups containing shear bands around the indents in both alloys. The as-cast bulk alloy has higher hardness and elastic modulus than the as-spun ribbon alloy. The difference in the strengths of two alloys may be related to the different amount of free volume. The strength seems to be more sensitive to a cooling rate during solidification than the plastic-flow behavior in the Cu60Zr30Ti10. [Copyright &y& Elsevier]

The glass forming abilities (GFA) of Mg65Cu25-xY10Nix alloys were investigated by copper mold casting. The evolution of microstructure of master alloys and the structures of as-cast alloys were checked by optical microscopy, X-ray diffraction and differential scanning calorimeter. It was found that the highest GFA was not exactly at the eutectic point of the Mg65Cu25Y10 alloy according to the melting temperature analyzed. Mg65Cu25Y10 revealed a dendrite microstructure while Mg65Cu22Ni3Y10 exhibited a eutectic microstructure that had a relatively high GFA. The deviation of eutectic microstructure and the deviation of the best GFA composition from the eutectic point can be explained in terms of a skewed coupled eutectic zone, and the higher glass-transition temperature on the hypereutectic side. [Copyright &y& Elsevier]

The behavior of the cyclic deformation and fatigue crack propagation of Zr41.25Ti13.75Ni10Cu12.5Be22.5 (in at.%) bulk amorphous metals is investigated. Both fully amorphous and partially crystallized metals are characterized in order to understand the fatigue behavior of these different microstructures. Under fully reversed load control, both amorphous metals show stable cyclic strain response until final fracture. The partially crystallized metal shows an inferior fatigue resistance in comparison with that of the fully amorphous metal. The absence of definite crystalline microstructure in the amorphous metal and a relatively small area of stable crack propagation on the fracture surface are main reasons for the stable strain response under cyclic deformation. Similar to the ductile crystalline alloys, the fatigue crack propagation of both amorphous metals obeys Paris power-law relationship at intermediate growth rates. Both fully amorphous and partially crystallized metals show a similar law of fatigue crack propagation in that their values of threshold and fatigue exponents m are comparable. The mechanisms of fatigue crack propagation in the region of near-threshold and intermediate crack growth are similar to that of ductile crystalline alloys. The crystalline phases in the partially crystallized metals can retard the crack or act as sites of crack initiation when they are oriented at a suitable direction for that of crack propagation. [Copyright &y& Elsevier]