[en] Zr₄₈Nb₈Cu₁₄Ni₁₂Be₁₈ bulk metallic glass (BMG) with excellent glass-forming ability was prepared by water quenching method. The BMG exhibits high glass transition temperature T_g and onset crystallization temperature T_x, compared with Zr₄₁Ti₁₄Cu_12.5Ni₁₀Be_22.5 BMG. The crystallization processes, change of elastic constants, and density and hardness in the crystallization process were studied by using X-ray diffraction, differential scanning calorimetry and acoustic method. The shear modulus, Poisson ratio, density and hardness are found to be sensitive to the crystallization process. A striking softening of long-wavelength transverse acoustic phonons in the BMG relative to its crystallized state is observed. The linear expansion coefficient, determined by a dilatometer method, is α_TG=1.04x10^-5 K^-1 (300-656 K) for the BMG and α_TC=1.11x10^-5 K^-1 (356-890 K) for the crystalline alloy. The Mie potential function and the equation of state of the BMG are determined from the expansion coefficient and acoustic experiments

[en] The rate of exchange of the acidic hydrogen of tert-butylmalononitrile was examined by using tritium as a tracer, and the process was found not to be inhibited by hydronium ions in dilute aqueous hydrochloric acid solutions. This rules out the Swain-Grunwald mechanism for this reaction under these conditions. The bromination of malononitrile was investigated under conditions where reprotonation of the dicyanomethyl carbanion and its reaction with bromine occur at comparable rates, and the bromination reaction was found to have a specific rate twice that for reprotonation. Reprotonation therefore cannot be a diffusion-controlled process, and malononitrile is not a normal acid. The unusually large solvent kinetic isotope effects found for these cyanocarbon acid ionization reactions are explained by postulating that the transferring hydrogen and its positive charge are becoming associated with a solvent cluster rather than with a single water molecule. The thermodynamic acidity constant of malononitrile was determined to be 11.41 in aqueous solution at 25 ⁰C

[en] Interim storage is one major program of fuel cycle. Because there are some individuals staying or living very close to the ISFSI site that is being constructed, this paper examines the potential radiological consequences of hypothesized events for storage casks. This study uses ORIGEN, HOTSPOT and RESRAD software to calculate the source terms, acute dose and long-term dose, separately. The results show that explosive-induced buoyancy would disperse the source much farther than the site boundary in a sabotage accident. Nevertheless, the amount of radioactivity released to offsite would be very low, and the maximum dose received by any individual staying or living in the vicinity of ISFSI, even under the most conservative scenario, would be very much less than the local public relocation dose limit. (orig.)

[en] Fe₂NiZ (Z=Al, Ga, Si and Ge) Heusler alloys have been synthesized and investigated focusing on the phase stability and the magnetic properties. The experimental and theoretical results demonstrate that covalent bonding originating from p–d hybridization plays an important role in these alloys, which dominates the stability of the ordered structure but leads to a decrease of the band splitting. The electronic structure shows that the IV group main-group elements (Si and Ge) provide a stronger covalent effect than the III group elements (Al and Ga). The variations of the physical parameters, like lattice constants, atomic-ordering temperatures, magnetic moments and Curie temperature, can be attributed differences in covalent bonding in these alloy systems

[en] The density and acoustic velocities of a Ce₇₀Al₁₀Ni₁₀Cu₁₀ bulk metallic glass (BMG) under hydrostatic-pressure (up to 0.5 GPa) and in crystallized state in ambient conditions were measured in situ by a pulse echo overlap method. The pressure derivatives of velocities and Grueneisen parameters as well as the equation of state (EOS) of the BMG were determined and compared to those of various other BMGs and nonmetallic glasses. Surprisingly, the BMG, unlike other BMGs with normal mode stiffness, exhibits an anomalous soft longitudinal acoustic mode under pressure similar to that of typical oxide glasses. An unusually large softening of longitudinal acoustic phonons in the BMG, relative to its crystalline state, is also observed, analogous with that in oxide glasses. The possible origin for the anomaly is the intrinsic glassy structure containing short-range covalent bonds

[en] Fe-Si-B is a well known system of technical importance used for various applications due to promising magnetic properties and corrosion resistant. Melt spun ribbons (MSRs) of 50 mm thickness of Fe77.5, Si13.3, B9.2 alloy were produced by melt spinning technique. Master alloys were prepared by using 3-4 N pure metals. The alloys were characterized by X-ray diffraction (XRD), differential scanning calorimetry (DSC), stereo scan and scanning electron microscopy (SEM) techniques. Elemental analysis was conducted by energy dispersive X-ray analyzer (EDAX). DSC results confirmed that the alloy showed wide supercooled liquid region before crystallization indicating good thermal stability. Activation energy was calculated to be 397 kJ/mol. Vickers and nanohardness, and elastic modulus were measured. Nanohradness (H) to elastic modulus ((E) ratio (H/E) indicates existence of covalent bonding in Fe-B-Si amorphous alloy. It is expected that the alloy is fit for fabrication of small electronics components, jewelry applications, structural materials and core windings of Green transformers. (author)

[en] A position sensitive neutron detector was used to measure the scattering cross sections of 14.7 MeV neutron form Pb between 3⁰ and 9⁰. The method to correct the effects of finite positional resolution by unfolding positional spectrum was studied

[en] The intrinsic correlation between the fracture morphology evolution and the structural heterogeneity of flow units in a typical Zr_52.5Ti₅Cu_17.9Ni_14.6Al₁₀ (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.

[en] A position sensitive neutron detector was used to measure the scattering cross sections of 14.7 MeV neutrons from Pb between 3⁰ and 9⁰. The method to correct the effects of finite positional resolution by unfolding positional spectrum was studied. (author)

[en] Thermal and magnetic properties of Al, Sn and C modified Fe-P-Si-B amorphous alloys with compositions Fe_80-x-y-z Al_xSn_yP_12-zSi₄B₄C_z (in at%, x=3-5, y=1-7, z=0-6) were investigated. By suitable replacements of Fe by Al/Sn, and P by C in these alloys, the glass-forming ability is greatly enhanced. The super-cooled liquid region and reduced glass transition temperature were examined and compared to the modified alloys. Properties of Fe₇₄Al₄Sn₂P_12-zSi₄B₄C_z amorphous alloys are typically, with increasing z: saturation magnetization 1.28-1.38 T, coercive force around 40 A/m, Curie temperature of 547-595 K, the electrical resistivity decreases from 181 to 168 μΩ-cm. Magnetic inductance of the cast cores were also reported