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(Zr53Al11.6Ni11.7Cu23.7)1–x(Fe77.1C22.9)x (x=0−2.2, at.%) bulk metallic glasses (BMGs) were prepared by copper mold suction casting method. Their glass forming ability and physical and chemical properties were systematically investigated. The glass forming ability is firstly improved with increasing x, and then decreased when x exceeds 0.44 at.%. Both glass transition temperature and crystallization temperature are increased, while the supercooled liquid region is narrowed, with Fe–C micro-alloying. The hardness, yielding and fracture strength, and plasticity firstly increase and then decrease when x reaches up to 1.32 at.%. The plasticity of the BMG (x=1.32 at.%) is six times that of the Fe-free and C-free BMG. In addition, by the Fe–C micro-alloying, the corrosion potential is slightly decreased, while the corrosion current density increases. The pitting corrosion becomes increasingly serious with the increase of Fe and C content.

The effect of Fe-C alloy additions on thermal, mechanical and corrosive properties of (Cu50Zr40Ti10)1-x(Fe-C)x (x = 0–2.20 at%) alloys were systematically investigated. The results show that the Fe and C additions can enhance glass transition temperature Tg and onset crystallization temperature Tx, but narrow supercooled liquid region ΔTx. Work-hardening can be clearly observed for the Cu-based bulk metallic glasses (BMGs) containing Fe and C elements. The yield strength (σy), fracture strength (σf) and plastic strain (ep) are drastically increased by Fe-C alloy additions. The corrosion potential Ec increases and the corrosion current density ic decreases with increasing Fe and C contents. The studied Cu-based BMGs exhibit unique and novel anodic polarization behavior characterized by current platforms plus current serrations. The current serrations are much larger for the Cu-based BMGs with 0 ≤ x ≤ 1.32 at% than for those with 1.76 ≤ x ≤ 2.20 at%. The corrosion surface images are changed from the pits to the passive films by Fe-C alloy additions. The corrosion behavior gradually transforms from the pitting corrosion to the self-passivization with increasing Fe and C contents. The corresponding mechanisms are also discussed.

(Cu50Zr50)x(Cu73Ti27)100-x (x = 0.63–0.75 at.%) alloys are designed using the proportional mixing of Cu50Zr50 and Cu73Ti27 binary alloys. Their thermal, mechanical and corrosive properties as well as the glass forming ability (GFA) are systematically investigated. The results show that the studied Cu-based glass forming alloys are bulk metallic glass composites (BMGCs) with off-eutectic compositions and display work-hardening behavior. The glass transition temperature and the reduced glass transition temperature increase and then decrease with increasing x when x ≥ 0.74 at%, while on the contrary for the critical cooling rate and supercooled liquid region. Both yield strength and fracture strength firstly increase and then decrease with decreasing x when x ≤ 0.71 at%. The plastic strain of (Cu50Zr50)0.75(Cu73Ti27)0.25 BMGC is the largest among the studied Cu-based BMGCs. Potentiodynamic polarization measurements show that all studied BMGCs exhibit a step-like anodic polarization behavior, indicating two competitive procedures of pitting corrosion and self-passivization. The corrosion behavior gradually transforms from predominant self-passivization to the pitting corrosion with decreasing x. Both corrosion current density and onset passive current density of (Cu50Zr50)0.75(Cu73Ti27)0.25 BMGCs are two orders of magnitude lower than those of the other Cu-based BMGCs. The mechanisms for the GFA and the corrosion are also discussed. The present work would shed light on how to design and develop BMGCs with superior comprehensive performances.

The intrinsic heterogeneities of the metallic glasses can be activated through cryogenic thermal cycling, making irreversible structural changes after the treatment and inducing rejuvenation to the materials. Although the energy rise after cryogenic thermal cycling can be easily determined from calorimetry, the energy change made by the heterogeneities is unknown because of the difficulty in witnessing these heterogeneities. In this paper, we investigated the changes of a typical heterogeneity: the Fe3Si crystallite, embedded in two partially-crystallized Fe-based metallic glasses, and subsequently deduced its influence on the neighbouring glassy matrix. It was found that even in the initial, partially-crystallized alloys, the Fe3Si nanocrystals were under residual expansion. Furthermore, both expansion and contraction can be detected after cryogenic thermal cycling depending on the applied number of cycles. The maximum residual volumetric strain preserved after CTC is in the order of 0.1%. Moreover, the stored energy of both crystals and glasses are calculated and the total energy rise is determined at the order of 5–50 mJ/g. The study of partially-crystallized alloys not only provides a useful model of heterogeneous materials but also reflects the structural change of the glassy phases, making this method attractive in understanding the effects of thermo-mechanical processing on heterogeneities.

The investigation on the stress relief of magnetic materials is important both for the industrial process and the academic research. In this work, the stress effects on the magnetic characteristics in Fe-based metallic glasses (MGs) are investigated under the applied bending stress and various annealing treatments. It was found that both the magnetic induction intensity B and effective permeability μ′ decrease while coercivity Hc increases with the applied compressive stress, indicating that the compressive effect is dominant on the magnetic characteristics in Fe78Si9B13 MG ribbons. We also found that the wide domain wall movement and the rotation of the narrow domains are seriously affected by internal stress during the magnetization process. Our results reveal that the stress relief plays a critical role in improving magnetic properties of Fe-based MGs and are helpful for understanding the correlations between the stress, microstructure change and magnetic softness in magnetic MGs.

The intrinsic correlation between the fracture morphology evolution and the structural heterogeneity of flow units in a typical Zr 52.5 Ti 5 Cu 17.9 Ni 14.6 Al 10 (vit105) metallic glass (MG) upon annealing was investigated. By systematically tuning the annealing time at temperature below the glass transition temperature, a series of dimple-like fracture morphology were obtained, which is the unique fingerprint-like pattern for every annealing state. Based on the structural relaxation model of flow units, the evolution of the typical dimple sizes, the largest and smallest dimple size, with annealing were well fitted. Then the evolution of flow unit density was estimated from the fracture morphology evolution, which displays the same evolution trend with that measured from thermal relaxation. A stochastic dynamic model considering the interaction of activated flow units was proposed to analyze the effect of the initial flow unit density and the flow unit interaction intensity on the dynamic evolution of dimple distribution. Our work may provide a novel scheme to investigate the structural fingerprint information on flow units from fracture morphology, and enlighten the microscopic structural origin of the ductile-to-brittle transition during structural relaxation in MGs.

(Zr54Al10.2Ni9.4Cu26.4)100−xTix (x = 0–0.5, at%) bulk metallic glasses were prepared by water-cooled copper suction casting method. The Ti microalloying effect on glass forming ability and physical and chemical properties of Zr54Al10.2Ni9.4Cu26.4 glass forming alloy were systematically investigated. The glass forming ability is the largest for the Zr-based alloy with 0.3 at% Ti. The glass transition temperature is decreased by the Ti addition, while the supercooled liquid region is broadened. Both strength and plasticity are significantly enhanced by the Ti addition. The yield strength and the fracture strength firstly increase and then decrease when the Ti content reaches up to 0.3 at%. The plastic strain and the fracture strain increase with increasing Ti content. In addition, the corrosion potential is slightly decreased by the Ti addition. The corrosion current density increases with increasing Ti content. The pitting corrosion becomes increasingly serious with increasing Ti content. The honeycomb corrossion structure can be clearly observed when the Ti content reaches up to 0.5 at%. The corresponding mechanisms are also discussed in detail.

Room-temperature mechanical properties of Cu 50 Zr 40 Ti 10– x Ni x (0≤ x ≤4, mole fraction, %) bulk metallic glasses (BMG) with aspect ratios in the range of 1:1–2.5:1 and loading rates in the range of 1×10 −5 –1×10 −2 s −1 were systematically investigated by room-temperature uniaxial compression test. In the condition of an aspect ratio of 1:1, the superplasticity can be clearly observed for Cu 50 Zr 40 Ti 10 BMG when the loading rate is 1×10 −4 s −1 , while for Cu 50 Zr 40 Ti 10– x Ni x ( x =1–3, mole fraction, %) BMGs when the loading rate is 1×10 −2 s −1 . The plastic strain ( ɛ p ), yielding strength ( σ y ) and fracture strength ( σ f ) of the studied Cu-based BMGs significantly depend on the aspect ratio and the loading rate. In addition, the σ y of the studied Cu-based BMGs with an aspect ratio of 1:1 is close to the σ f of those with the other aspect ratios when the loading rate is 1×10 −2 s −1 . The mechanism for the mechanical response to the loading rate and the aspect ratio was also discussed.

A multicomponent metallic glass (MG) with highly efficient and anomalous durability for catalyzing water splitting is reported. The outstanding performance of the MG catalyst contributed by self-optimized active sites originates from the intrinsic chemical heterogeneity and selective dealloying on the disordered surface; thus, a new mechanism for improving the durability of catalysts is uncovered.

(Zr53Al11.6Ni11.7Cu23.7)1-x(Fe77.1C22.9)x (x = 0–2.2 at.%) bulk metallic glasses (BMGs) were prepared by water cooling copper mold suction casting and their isochronous crystallization characteristics are investigated. The glass transition temperature, crystallization temperature, and crystallization peak temperature for all studied Zr-based BMGs firstly increase with increasing heating rate, and then decrease when the heating rate increases up to 60 K/min for the BMGs (0 ≤ x ≤ 0.88 at.%) and 80 K/min for the BMGs (1.32 ≤ x ≤ 2.20 at.%). The glass transition temperature, crystallization temperature, glass transition activiation energy, crystallization activiation energy, and activiation energy for crystallization peak temperature of the Fe- and C-free Zr-based BMG are the smallest among the studied BMGs, indicating that Fe and C additions are benificial to delaying the glass transition and the crystallization. Fe and C additions influence more significantly on the glass transition than on the crystallization. The local crystallization activiation energy for the Fe- and C-free BMG are the smallest among the studied BMGs, indicating that the crystallization is easy for the Fe- and C-free BMG. The peak height of local Avrami exponent and its corresponding crystallization fraction decrease with increasing heating rate except for the BMG (x = 1.32 at.%). The fragility indexes are 32–48 for the studied Zr-based BMGs. The present results are of guiding significance for preparing the excellent BMG composites by heat treatment and selecting suitable conditions for forming the BMGs.

The thermal, mechanical and corrosive properties of (Cu45Zr45.5Ti9.5)100-xAlx (x = 0–0.25 at%) glass forming alloys were systematically studied. The thermal measurements show that Al microalloying leads to increase of glass transition temperature but decrease of supercooled liquid region. The glass transition activation energy slightly increases and then decreases with increasing Al content. The room-temperature compression tests demonstrate that all studied Cu-based bulk metallic glasses (BMGs) exhibit work-hardening behavior, but the work-hardening capacity depends on Al content. In addition, yield strength, fracture strength and fracture strain are drastically increased by Al addition. The largest plasticity of (Cu45Zr45.5Ti9.5)99.8Al0.2 BMG is 6 times larger than that of the Al-free Cu-based BMG. Moreover, the electrochemical measurements indicate that the Al minor addition cause the decrease of both corrosion potential and corrosion current density. The corrosion behavior gradually transforms from the pitting corrosion to the self-passivization with increasing Al content. The local heterogeneity of Al element is thought to be the reason for the performance change of the studied Cu-based BMGs. The present results would provide a new insight into the mechanism for the microalloying effect on the properties of the metallic glasses.

This study explores nanosecond-pulsed (ns-pulsed) laser welding on the metallic glass (MG) ribbons of four compositions: Fe78Si9B13, Zr65Cu15Ni10Al10, La55Ni20Al25 and Ce65Al10Cu20Co5. All MGs can be welded in the air by the ns-pulsed laser, and the crystallization of the welding joints can be avoided by proper control of the laser parameters. By varying the travel speed, pulse duration and repetition frequency, the critical crystallization time of MG can be quickly detected in a high-throughput way by ns-pulsed laser welding. At the optimal processing conditions, 70–90% of the tensile strength of the parent melt-spun ribbon can be preserved in the welded MG ribbons. The mechanical strength is well linked to the profile of the welding joint, which suggests a simple method to evaluate the welding quality. A welding parameter map has been established based on the experiments, and it is concluded that the laser power-density per sample thickness and the interaction time are the key factors that control the crystallization and strength of the welding joints. The map is valid for a broad range of MG compositions of all sample thickness, and thus the optimal processing conditions may be extended to all MGs with equivalent glass-forming ability.

Effect of network structure on plasticity and fracture mode of Zr–Al–Ni–Cu bulk metallic glasses (BMGs) was investigated. The microstructures of transversal and longitudinal sections were exposed by chemical etching and observed by scanning electron microscopy (SEM). The mechanical properties were examined by room-temperature uniaxial compression test. The results show that both plasticity and fracture mode are significantly affected by the network structure and the alteration occurs when the size of the network structure reaches up to a critical value. When the cell size (dc) of the network structure is ∼s3 μm, Zr-based BMGs characterize in plasticity that decreases with increasing dc. The fracture mode gradually transforms from single 45° shear fracture to double 45° shear fracture and then cleavage fracture with increasing dc. In addition, the mechanisms of the transition of the plasticity and the fracture mode for these Zr-based BMGs are also discussed.

Phase formation, glass forming ability, mechanical and thermal properties of Cu50Zr50−x Al x (0⩽x⩽11.0) glass forming alloys were systematically investigated. The results show that Cu50Zr47Al3 alloy has the best glass forming ability (GFA), lowest fragility index (m) and highest fracture strength. There are B2 CuZr and B19′ CuZr phases for Cu50Zr50−x Al x (0⩽x⩽5.0) alloys. B2 CuZr phase disappears and two new phases (Cu10Zr7 and CuZr2) appear when 5.05.0). Cu50Zr50−x Al x (0⩽x⩽4.0) alloys are off-eutectic compositions while near-eutectic compositions for Cu50Zr50−x Al x (5.0⩽x⩽11.0) alloys. The E g, E x, and E p decrease with increasing sensitive factor (β) for the studied Cu-based alloys characterized in the room-temperature brittleness. The dependence of the phase formation and GFA on the Al content is discussed.

Glass forming ability, thermal, electrical and mechanical properties of Cu50Zr40Ti10 − xNix (0 ≤ x ≤ 4.0 at%) glass forming alloys were systemically investigated. It is found that the critical dimension of the present Cu-based glass forming alloys firstly increases with increasing Ni content, then decreases when Ni >2.0 at%. Ni addition results in the increase of the electrical resistivity and the thermal conductivity. The glass transition temperature increases with increasing Ni content for the present Cu-based BMGs at all studied heating rates. However, there are complex correlations for the other characteristic temperatures, crystallization enthalpy and activation energy with the Ni content and heating rate, respectively. The plastic strain firstly increases with increasing Ni content, then decreases when Ni >2.0 at%. Both yield strength and compression strength nearly increase with increasing Ni content. The plastic strain increases with decreasing m in the range of 0 ≤ Ni ≤ 2.0 at% and 2.0 ≤ Ni ≤ 4.0 at% for present Cu-based BMGs. The m linearly decreases with increasing dc for the present cu-based BMGs. The corresponding mechanisms are also investigated.

A series of Zr-Al-Ni-Cu bulk metallic glasses (BMGs) with network structures were carefully designed and their heterogeneous microstructures were investigated by carefully etching the cross sections of these BMGs. It is found that the heterogeneous microstructures of these BMGs can be uncovered by etching with mixed solution of HF and HNO3. Some of the studied Zr-based BMGs characterize in micrometer network structure. The cell size of the network structure depends on the composition of the BMG and is related with the fractural mode and mechanical property. The found network structure of the Zr-based BMGs benefits for understanding the unique mechanical properties of the Zr-based BMGs. (C) 2014 Elsevier Ltd. All rights reserved.

The dynamic evolutions of different fracture morphologies in the fracture surface of brittle Mg-based metallic glasses (MGs) were systematically and quantitatively studied by SEM and AFM. It shows that the evolution of the fracture morphology pattern is dominated by an effective dynamic parameter of critical crack tip curvature radius. Based on crack tip plastic zone and shear transformation zone (STZ) theories, a theoretical model for the evolution of the crack tip curvature radius by considering the activation of STZs during fracture was proposed. The model can simulate the crack propagation process, and predict the critical crack tip curvature radius and the fracture pattern transition between the dimples and the periodic corrugations solely occurring in brittle MGs. These results have implications for understanding the microscopic fracture mechanism and the structural origin of fracture in MGs.

Mechanism, condition and characteristics for the formation of the network structure in a group of Zr-Al-Ni-Cu bulk metallic glasses (BMGs) were investigated. The results show that the constituent segregation and/or the symplastic growth would be the mechanisms for the formation of the cell structure in the present Zr-Al-Ni-Cu BMGs. The cell structure can be easily obtained for the glass forming alloys whose compositions locate nearby the eutectic point. The shorter the distance is from the eutectic point, the larger the cell and the thicker the cell wall of the network structure will be. The present investigation would provide useful information for the development of the BMG with the network structure.

We report that the glass transition temperature (Tg) of a variety of metallic glasses (MGs) correlates with the eutectic or peritectic temperature of two main components corresponding stoichiometric proportion in their binary phase diagram. The correlation suggests that the Tg of MGs is mainly determined by their solvent of two base components, which have composition close to the eutectic and peritectic points in the binary phase diagram and the weakest link in amorphous structure. The results have implications for understanding the structure and glass transition in MGs and for predicting and designing metallic glasses with a desirable Tg.

Cu50Zr40Ti10 (at%) glassy ribbon was prepared by melt spinning. The effect of mechanical tension on its thermal and corrosive properties was investigated by differential scanning calorimetry and electrochemical polarization experiments, respectively. After mechanical tension, the crystallization temperature and the crystallization enthalpy almost maintain the same, while the relaxation temperature and the glass transition temperature decrease. In addition, the activation energy of the glass transition decreases from 74.8 +/- 1.7 KJ mol(-1) to 71.0 +/- 1.9 KJ mol(-1). The activation energy of the relaxation decreases from 70.0 +/- 4.4 KJ mol(-1) to 50.5 +/- 3.8 KJ mol(-1) at low heating rate, while increases from 186.1 +/- 9.4 KJ mol(-1) to 289.4 +/- 9.4 KJ mol(-1) at rapid heating rate. On the other hand, corrosion potentials polarized in all studied solutions sharply decrease, while the corrosion current densities increase. The pitting corrosion vanishes in 1 M chloride-containing solutions. The passive potential and the passive current density both decrease in 0.5 M H2SO4. The corroded surface micrographs in all studied solutions remarkably change. In addition, the difference of corrosive behavior in 0.5 M H2SO4, 1 M HCl, and 1 M NaCl is also discussed. (C) 2013 Elsevier B.V. All rights reserved.

A group of plastic Zr-Al-Ni-Cu bulk metallic glasses (BMGs) with low Zr content was developed and their thermal and mechanical properties were investigated. The results show that these Zr-based BMGs have a single crystallization event for all heating rates in the studied temperature region. The glass transition temperature Tg decreases with increasing Zr content for all heating rates. There are two melting procedures for the BMGs whose Zr content is less than 52 at %, while three melting procedures for the other Zr-based BMGs. The second melting procedure is split into two melting procedures for Zr52.5Al12.2Ni12.6Cu22.7 and Zr53Al11.6Ni11.7Cu23.7 BMGs, while the first melting procedure is split into two melting procedures for the other BMGs. The activation energy decreases with increasing sensitivity index β for the studied Zr-based BMGs. The plastic strain ep is in the region of 0.2%-19.1% for these Zr-based BMGs. Both yield strength σy and fracture strength σf are smallest for Zr55Al8.9Ni7.3Cu28.8 BMG whose ep is largest among all studied Zr-based BMGs and reaches up to 19.1%. In addition, the mechanism for the large difference of the plasticity among the studied Zr-based BMGs is also discussed.

Intensive studies show that the best glass-forming ability (GFA) is presented as the Fermi surface made contact with pseudo-Brillouin boundaries. Via surveying the GFA of electronic simple Ca–Mg–Cu metallic glass system, we find that the best GFA is presented as the free electrons per atom (e/a) equals to 1.75, which is closed to the value of 1.8 proposed for the ideal amorphous state. The pseudo-gap or minimum in the density of states at the Fermi surface proposed by nearly free electron theory has not been observed in the Ca–Mg–Cu system. Our results indicate that the free electron concentration is an important but not the sole factor for influences in the glass formation.

Bulk metallic glasses (BMGs) are usually based on a single principal element such as Zr, Cu, Mg and Fe. In this work, we report the formation of a series of high mixing entropy BMGs based on multiple major elements, which have unique characteristics of excellent glass-forming ability and mechanical properties compared with conventional BMGs. The high mixing entropy BMGs based on multiple major elements might be of significance in scientific studies, potential applications, and providing a novel approach in search for new metallic glass-forming systems.

The tensile behaviors of a series of (Zr47.5Cu47.5Al5)1 − x(Zr80Nb20)x (x = 0, 0.05, 0.10, 0.15) bulk metallic glasses were studied at ambient and cryogenic (77 K) temperatures. It is found that the tensile strength of the alloys increases as the temperature decreases from 298 K to 77 K. The maximum enhancement is 15.7%, and the toughness of these alloys does not deteriorate at low temperatures. We demonstrate that the higher energy required to raise the temperature in the shear bands from the cryogenic temperature to glass transition temperature is the origin of the tensile strength enhancement at low temperatures.

Ta-based bulk metallic glasses with high strength (2.7 GPa) and hardness (9.7 GPa), high elastic modulus (170 GPa) and high density (12.98 g/mm(3)) were developed. The best glass forming ability so far for a Ta-Ni-Co system reaches a critical diameter of 2 mm by the copper mold casting method. It shows an exceptionally high glass transition temperature of 983 K and a high crystallization temperature up to 1023 K. The unique mechanical and physical properties make them a promising high strength material. (C) 2011 Elsevier B.V. All rights reserved.

The effects of stress relief on the magnetic characteristics of Fe-based metallic glass (MG) ribbons are investigated under external stress through various annealing treatments. We found that long-time annealing treatments benefit for making softer magnetic MGs under applied bending stress. We show that the irreversible domain wall movement region and the irreversible domain wall rotation region in the M-H curve represent the stress relief, which can be well reflected by the demagnified magnetic anisotropy. The magnetic coercivity and effective permeability variations in the lower frequency regime also represent the stress relief state. These observations have implications for understanding the relationship between the stress relief, microstructure change, and magnetic softness in magnetic MGs and might be helpful for the performance improvement of the ferromagnetic glassy materials.

The purpose of this work was to study the giant strong component (GSC) of B. thuringiensis metabolic network by structural and functional analysis. Based on so-called "bow tie" structure, we extracted and studied GSC with its functional significance. Global structural properties such as degree distribution and average path length were computed and indicated that the GSC is also a small-world and scale-free network. Furthermore, the GSC was decomposed and functional significant for metabolism of these divisions were investigated by comparing to KEGG metabolic pathways.

The purpose of this work was to study the giant strong component (GSC) of B. thuringiensis metabolic network by structural and functional analysis. Based on so-called "bow tie" structure, we extracted and studied GSC with its functional significance. Global structural properties such as degree distribution and average path length were computed and indicated that the GSC is also a small-world and scale-free network. Furthermore, the GSC was decomposed and functional significant for metabolism of these divisions were investigated by comparing to KEGG metabolic pathways.O objetivo deste trabalho foi realizar uma análise estrutural e funcional do GSC (Giant Strong Component) da rede metabólica de Bacillus thurigiensis. Baseando-se na estrutura bow-tie, o GSC foi extraído e analisado quanto ao sue significado funcional. Propriedades estruturais globais tais como grau de distribuição e tamanho médio da via metabólica foram mensuradas, concluindo-se que o GSC é também uma rede small world e scalefree. Além disso, a rede GSC foi decomposta e as divisões com significância funcional no metabolismo foram comparadas às vias metabólicas KEGG.

A novel compact wideband circularly-polarized (CP) helix antenna is presented in this paper. Unlike conventional helical geometry, our design adopts a tapered metal strip which is rolled into a conical shape and is simply fed by attaching to a 50Ω coaxial cable. All the configuration parameters are optimized by using modified multiobjective evolutionary algorithm based on decomposition (MOEA/D) for broad operation bandwidth. The proposed helix antenna provides a -10 dB impedance bandwidth of more than 81% from 2.1GHz to above 5GHz, a 3-dB axialratio bandwidth of 58% (2.4GHz~4.36GHz), and a 8dBi axial gain bandwidth of 72.5% (2.18GHz~4.66GHz), which leads to an effective CP operation bandwidth of 58%. The overall size of the design is 40mm×40mm× 40mm, i.e., 0.45λ×0.45λ×0.45λ at the centre frequency of 3.38GHz. The compact size and wideband CP performance of this antenna make it promising for high speed wireless communication systems today. Keywordscircular polarization; helical antenna; conical helix; wideband antenna

Experimental investigations and modeling of nonlinear elasticity of fiber-reinforced soil under cyclic loading at small strain are conducted in this paper. The investigations include three aspects. First, cyclic shear tests are conducted using conventional triaxial apparatus. Twenty-seven specimens with three different fiber contents are employed to conduct triaxial cyclic shear tests under different confining pressure and loading repetition. Effects of geofiber, confining pressure and loading repetition on elastic shear modulus of reinforced soil are studied and analyzed. Second, a hyperbolic function is introduced to describe the nonlinear stress–strain skeletal curve under cyclic loading. Nonlinear elastic modulus is expressed as a function of shear strain and two variables A and B that are related to the initial tangential modulus and ultimate cyclic loading stress, respectively. In the present paper, variables A and B both are further assumed to be functions of geofiber content, confining pressure and loading repetition. Finally, eight constitutive coefficients of the nonlinear elastic model are calibrated using stress–strain curves from cyclic triaxial shear tests. The calibration of parameters is conducted using the technique of the linear regression for multiple variables. Impacts and effects of geofiber, confining pressure and loading repetitions on soil nonlinear elastic behavior are discussed.

Fe-based metallic glasses (MGs) with excellent soft magnetic properties are applicable in a wide range of electronic industry. We show that the cryogenic thermal cycle has a sensitive effect on soft magnetic properties of Fe78Si9B13 glassy ribbon. The values of magnetic induction (or magnetic flux density) B and coercivity H c show fluctuation with increasing number of thermal cycles. This phenomenon is explained as thermal-cycle-induced stochastically structural aging or rejuvenation which randomly fluctuates magnetic anisotropy and, consequently, the magnetic induction and coercivity. Overall, increasing the number of thermal cycles improves the soft magnetic properties of the ribbon. The results could help understand the relationship between relaxation and magnetic property, and the thermal cycle could provide an effective approach to improving performances of metallic glasses in industry.

A supercooled liquid extraction method and apparatus for micro and nanoscale metallic glassy fiber preparation was developed. Using the fiber fabrication equipment, micro to nanoscale metallic glassy fibers with diameter ranging from 70 nm to 300 μm can be obtained by wire drawing in the supercooled liquid region of metallic glasses via superplastic deformation. The obtained metallic glassy fibers possess precisely designed and controlled sizes, high structural uniformity and high degree of surface smoothness.

A new car in operation of only 8,000 km, because of malfunction, resulting in lost control and rammed into the edge of the road, and then the basic vehicle scrapped. According to the investigation of the site, it was found that the tie-rod of the car had been broken. For the subjective analysis of the accident and identifying the true causes of rupture of the tierod, a series of studies, from the angle of theory to experiment on the bended broken tie-rod, were conducted. The mechanical model was established; the stability of the defective tie-rod was simulated based on ANSYS software. Meanwhile, the process of the accident was simulated considering the effect of destabilization of different vehicle speed and direction of the impact. Simultaneously, macro graphic test, chemical composition analysis, microstructure analysis and SEM analysis of the fracture were implemented. The results showed that: 1) the toughness of the tie-rod is at a normal level, but there is some previous flaws. One quarter of the fracture surface has been cracked before the accident. However, there is no relationship between the flaw and this incident. The direct cause is the dynamic instability leading to the large deformation of impact loading. 2) The declining safety factor of the tie-rod greatly due to the previous flaws; the result of numerical simulation shows that previous flaw is the vital factor of structure instability, on the basis of the comparison of critical loads of the accident tie-rod and normal. The critical load can decrease by 51.3% when the initial defect increases 19.54% on the cross-sectional area, which meets the Theory of Koiter.

Superhydrophobic surface with mechanical stability and corrosion resistance is long expected due to its practical applications. We show that a micro-nano scale hierarchical structured Pd-based metallic glass surface with superhydrophobic effect can be prepared by the thermoplastic forming, which is a unique and facile synthesis strategy for metallic glasses. The superhydrophobic metallic glass surface without modification of low surface energy chemical layer also exhibits superior mechanical stability and corrosion resistance compared with conventional superhydrophobic materials. Our results indicate that the metallic glass is a promising candidate superhydrophobic material for applications.

In metallic glasses (MGs), a clear correlation has been established between plasticity and the Poisson's ratio. Such a correlation between the two distinctive macroscopic mechanical properties is challenging to explain from a microstructure perspective. We studied the microstructural origin of the Poisson's ratio and plasticity criterion in various MGs and find a correlation between the relative concentration of flow units and Poisson's ratio: the MGs with higher concentration of flow units show a larger Poisson's ratio and better plasticity. We have explained the empirical correlation between ductility and the Poisson's ratio based on microscopic flow units in MGs.

The flow units of glasses are generally perceived to be a local rearrangement of atoms that are microstructural origin for plastic deformation and relaxations in metallic glasses. We find a relationship of the effective concentration of flow units and some properties such as elastic moduli, micro-hardness and plasticity of metallic glasses. The relationship helps in understanding the softening phenomenon, structural heterogeneous, evolution process of flow units, and widespread mechanical behavior of metallic glasses and can reveal the essential structural mechanism of the Poisson's ratio criterion for plasticity in metallic glasses. The relationship also indicates that the flow unit is a key structural parameter for understanding and controlling the properties and the performance of metallic glasses.

The evolution of flow units associated with the flow “defects” in metallic glass is characterized by monitoring the metallic glassy density change upon isothermal annealing far below their glass transition temperature. A meaningful function for the density variation with the concentration of flow units is obtained for the metallic glasses. We show that the correlation between the density variation and the flow unit have implications for understanding the fragility, structural heterogeneous, and structural relaxation behaviors in metallic glasses.

It has been postulated that metallic glasses, in contrast to their crystalline counterparts, exhibit nano-scale structural heterogeneity which is crucial for understanding the long-standing issues of relaxations and deformation of glasses. We fabricate micrometer scale metallic glassy fibers (MGFs) with different diameters and structural configurations, and find that the thinner MGFs cooled down with faster cooling rates have smaller superconducting transition temperatures and wider transition widths. We show that the superconducting properties correlate with the heterogeneous microstructure of metallic glasses and can be used as a novel way to experimentally characterize the structural heterogeneity of metallic glasses.