The correlation among apparent global plasticity, Poisson’s ratio, and fragility in monolithic bulk metallic glass (BMG) alloys has been investigated in the present study. The shear and bulk moduli in monolithic Cu-based BMG alloys have been measured by resonant ultrasound spectroscopy (RUS) and ultrasonic technique. The Cu43Zr43Al7Ag7 BMG alloy showing a large apparent global plasticity (∼8%) exhibits a high Poisson’s ratio when compared with that of Cu43Zr43Al7Be7 BMG alloy. In addition, the fragility of Cu-based BMG alloys can be obtained by differential scanning calorimetry (DSC). The fragility index m of Cu43Zr43Al7Ag7 BMG alloy is slightly larger than that of Cu43Zr43Al7Be7 BMG alloy. The correlation between Poisson’s ratio and fragility in BMG alloys can be presented by a simple relation of m − 17 = 14 (B∞/G∞ − 1). Poisson’s ratio and fragility might be regarded as an important parameter that controls global plasticity of glass-forming alloys.

We report a novel finding of slither propagation of shear bands on the fracture surface of a Cu47.5Zr47.5Al5 bulk metallic glass (BMG). The nanoscale heterogeneities in the as-cast state are aggregated along shear bands with irregular morphology. Such heterogeneities create a fluctuating stress field during shear band propagation leading to a slither propagation mode. The slither propagation of 10 to 15 nm wide shear bands is effective to improve both the plasticity and the “work-hardening-like” behavior of BMGs if the size, the morphology, and the elastic properties of the heterogeneities are intimately intercalated during solidification.

We present a simple method for preparing nanometer-sized, Ti-based amorphous powders from the Y28Ti28Al24Co20and Y36Ti20Al24Co20two-phase amorphous alloys. The initial microstructure of these rapidly quenched alloys is composed of Ti-based, amorphous, spherical, nanometer-sized particles embedded in a Y-based amorphous matrix, with particle size dependent on the alloy composition. The Ti-based powders were extracted from the two-phase amorphous alloys through selective dissolution of the Y-rich matrix in a 0.1 M HNO3solution. The powders of size ranging between 20 and 200 nm have smooth and spherical morphology, and exhibit different magnetic behavior than the bulk alloy of identical composition.

We synthesized bulk amorphous alloy systems of Cu43Zr43Al7X7 (X = Be, Ag; numbers indicate at.%), with the objective of simultaneously enhancing the glass-forming ability (GFA) and the plasticity. The alloys not only exhibit high plasticity (∼7%, ∼8%), but also possess enhanced GFA (alloys with 12 and 8 mm diameter). The possible mechanisms underlying this enhanced GFA and plasticity exhibited by these alloys are discussed based on the atomic-packing state and atomistic-scale compositional separation associated with the mixing enthalpy difference. A strategy for designing bulk amorphous alloys with simultaneous improvement in the GFA and the plasticity is proposed from the viewpoint of atomic-packing state and atomistic-scale phase separation.

We report the hydrogenation characteristics and mechanical properties of Ti50Zr25Cu25 in situ composite ribbons, composed of β-Ti crystalline phase dispersed in an amorphous matrix. Upon cathodic charging at room temperature, high hydrogen absorption up to ∼60 at.% (H/M = ∼1.2) is obtained. At such a high concentration, hydrogen-induced amorphization occurs. Mechanical tests conducted on the composite with varying hydrogen concentrations indicate that the Ti50Zr25Cu25 alloy is significantly resistant to hydrogen embrittlement when compared to conventional amorphous alloys. A possible mechanism that would contribute toward hydrogen-induced amorphization and hydrogen embrittlement is discussed.

Taenia solium cysticercosis is a parasitic disease frequently affecting human health and the pig industry in many developing countries. A synthetic peptide vaccine (designated S3Pvac) against porcine cysticercosis has been developed previously as an aid to interrupt transmission and has been shown to be effective. The results of the present study support the effectiveness of the vaccine under endemic field conditions. However, given the time-frame of the vaccination trial, no changes in the local levels of transmission were detectable before and after vaccination using sentinel pigs. Thus, this investigation shows the limited usefulness of single vaccination as the sole means of interrupting Taenia solium transmission in an endemic region.

The effect of rotation on mixing across a density interface is studied experimentally in a two-layer stratified fluid. Mixing is caused by turbulence produced in one of the layers by an oscillating grid. The flow depends on the Richardson number Ri = g′l/u2 and the Rossby number Ro = u/2Ωl. The most important result is the observed decrease of the entrainment rate E in the presence of rotation, when compared with non-rotating experiments. In a certain range of the two parameters, a general entrainment law in the form E = 0.5RoRi−1 is established, whereas the entrainment law in non-rotating conditions is $E = 1.6 Ri^{-\frac{3}{2}}$. Additional information concerning the dynamics of the interface in rotating conditions is provided by interface displacement spectra, showing that rotation favours low-frequency oscillations of the interface, whereas high-frequency oscillations are not modified by rotation. Finally, the role of inertial waves is discussed on the basis of velocity measurements in the non-stirred layer.

Fe element was partially substituted by Zr and Co in an attempt to enhance the glass-forming ability, and mechanical and soft magnetic properties of Fe74-xNb6B17Y3(Zr, Co)x (x = 3, 5, 8) amorphous alloys. Both partial replacements resulted in the enhancement of the glass-forming ability, and 3-mm diameter rods with a fully amorphous structure were prepared by a copper mold casting method. Zr and Co containing Fe-based bulk amorphous alloys exhibited high compressive fracture strength of about 4 and 3.5 GPa, respectively. However, Zr and Co induced different effects on the magnetic properties. Whereas the partial replacement of Fe by Zr was found to decrease dramatically the saturation magnetization, the partial replacement of Fe by Co provided an increase of about 25% of the saturation magnetization.

The oxidation behavior in air of gas atomized Al–Cu–Fe–Be powders was investigated during isothermal exposures at 750, 800, and 830 °C. Oxidation data obtained at 750 °C for Al–Cu–Fe and Al–Cu–Fe–Cr powders are also presented and used as references. Thermogravimetric analyses showed that Be significantly improved the oxidation resistance of the icosahedral phase at 750 °C. At this temperature the i-phase in Al–Cu–Fe–Be powders was found to be stable even after oxidation for 300 h, while oxidation at and beyond 800 °C led to the formation of a cubic β′-phase. Auger analyses suggested that, in addition to its role on the stability of the icosahedral phase, the presence of Be in the oxide layer provided efficient protection against air oxidation at high temperature.

Samples with a target composition of Al62.5Cu25Fe12.5 (at.%) have been produced from the repeated cold rolling and folding (R&F) process of Al, Cu and Fe elemental foils. Upon early increments of the R&F cycle, the mechanically-induced process led to the fragmentation of the initial foils, which resulted in the dispersion of elemental Fe layers through the refined Al and Cu layers. After 40 R&F cycles the Al2Cu phase was detected, while Fe did not contribute to the formation of compounds. Thermal analyses suggested that the formation and dissolution of the Al2Cu and Al7Cu2Fe phases are critical steps for the synthesis of the i-phase during post-R&F treatment. Annealing between 650° and 750°C enabled the formation of the stable i-phase and resulted in high values of the microhardness.

Phase formation and thermal stability for an Al–Mn–Be alloy have been investigated by melt-spinning and conventional casting. Significant differences in the phase formation and the thermal stability of the microstructure were found as a result of the different cooling rates. In the melt-spun ribbons, a large volume fraction of a metastable icosahedral phase was found to coexist with an Al solid solution. In the bulk cast ingots, the primary phase formed in the two-phase microstructure was a hexagonal approximant phase of quasicrystals. This phase that solidified in the form of faceted particles embedded in the Al solid matrix proved to be thermodynamically stable during annealing at 540 °C for 100 h. The effect of Be addition on the formation of the stable approximant phase is discussed in terms of the Hume–Rothery mechanism.

In this article, we present a laboratory astrophysics experiment on radiative shocks and its interpretation using simple modelization. The experiment is performed with a 100-J laser (pulse duration of about 0.5 ns) which irradiates a 1-mm3 xenon gas-filled cell. Descriptions of both the experiment and the associated diagnostics are given. The apparition of a radiation precursor in the unshocked material is evidenced from interferometry diagrams. A model including self-similar solutions and numerical ones is derived and fairly good agreements are obtained between the theoretical and the experimental results.

The remote field eddy current technique is used for dimensioning the grooves that may occur in the ferromagnetic pipes. We propose a method to estimate the depth and the length of corrosion grooves from measurement of a pick-up coil signal phase at different positions close to the defect. Groove dimensioning requires the knowledge of the physical relation between measurements and defect dimensions; therefore finite-element calculations are performed to design parametric algebraic functions for modeling the physical phenomena. Different models are possible; the choice of this algebraic function is discussed from identification criteria. By means of new measurement formalism and two previously defined measurement relations, estimates of groove sizes may be given. In the first approach, algebraic function parameters and groove dimensions are linked through a polynomial function; this approach is proved to be better than a second one which tries to take advantage of more physical considerations.

Quasicrystalline coatings with various aluminum based systems were deposited onto 304 stainless steel substrates using two thermal spraying techniques; plasma spraying and high velocity oxy-fuel spraying. The friction and wear performances of the coatings were evaluated using two different testing devices, varying testing conditions and counterpart materials. Values of the friction coefficient were found to be strongly dependent on the testing devices and the counterpart materials, with values ranging from 0.15 to 0.4. In testing conditions corresponding to high sliding velocity, this study showed that the contact problem was posed over a third body system due to the formation of an intermediate layer. Values of the coefficient of friction were found to be approximately the same for all coating layers regardless of the thermal spraying techniques used, however, larger differences were obtained in the wear performance. The tribological properties were also evaluated at high temperature. It is noted that quasicrystal coating layers exhibit better friction and wear performances at 450oC than at room temperature. In comparison to potential coating candidate such as Cr2O3 for piston rings in automotive engines, tribological property of quasicrystalline coating layers seems to be promising one, however, wear performance need to be improved.

Spark plasma sintering method was applied to Al-Cu-Fe and Al-Si-Cu-Fe gas-atomized powders to prepare almost pore-free cylindrical specimens with icosahedral and 1/1 cubic approximant phases, respectively. This investigation has revealed that a high density could be obtained despite the short period and low temperature imposed during spark plasma sintering. In comparison to hot press technique, these conditions are favorable since they limit the formation of secondary phases and avoid exaggerated grain growth. The Vickers microhardness and fracture toughness of these two alloy systems were found to be larger than those obtained from cast and hot pressed samples, which could be attributed to a strong bonding between powder particles and the small-grained microstructure of the bulk SPS quasicrystalline specimens.