On the Nature of the Excess Internal Energy and Entropy of Metallic Glasses

JETP Letters - The excess internal energies ΔUQ and excess entropies $$Delta {{S}_{Q}}$$ of ten metallic glasses with respect to their parent crystalline states are determined from...     

Neutrino Mixing in Matter at Extreme High Energy

We have studied neutrino mixing at extreme high energy considering two flavour framework with matter effects. We analyze the atmospheric neutrino data within the simplest scheme of two neutrino oscillation. We consider as special case of matter density profile, which are relevant for neutrino oscillations. In particular, we compute to constrain a specific from of neutrino mass square difference and mixing in extreme high energy in matter. The dispersion relation for the neutrino mixing in neutrino oscillation in matter are discussed.     

Relaxation-Induced Changes in High-Entropy Bulk Metallic Glasses

Journal of Experimental and Theoretical Physics - The relaxation of the shear elasticity of high-entropy bulk metallic glasses (HEBMGs) in the initial (as-quenched) and relaxed (aged) states is...     

Hf-基非晶合金的力学性能研究

 利用MTS810实验机和分离式霍普金森压杆（SHPB）,对Hf_44.5Cu₂₇Ni_13.5Ti₅Al₁₀块体非晶合金进行了准静态和动态压缩实验,应变速率范围为10^-4~10³ s^-1,给出了不同应变速率下非晶合金的应力-应变曲线,并对其压缩断口形貌进行了扫描电镜观察。结果表明：在准静态压缩条件下,Hf_44.5Cu₂₇Ni_13.5Ti₅Al₁₀非晶合金不具有应变速率敏感性,在由放射区和扇形区组成的断口形貌上观察到纳米级韧窝和60 nm左右的周期性条纹结构;在动态压缩条件下,随着应变速率的增加,动态屈服强度明显减小,合金具有应变速率敏感性,同时断裂表面为夹杂着脉络条纹的絮状结构。进一步观察发现,动态压缩断口上存在3种特征断裂形貌：树枝状条纹、典型脉络花纹和合金熔体。     

Formation of Pd-Ni Based Bulk Metallic Glasses

Bulk metallic glasses are prepared in Pd4o.sNi4o.sSixP19-x （x = 0-14 at.%） alloys by a combination of flux treatment and water quenching technique. It is found that the thermal stability of the Pd4o.sNi4o.sSixP19=x glassy alloys depends on the addition of Si content. Among the Pd4o.sNi4o.sSixP19=x glassy alloys studied, the Pd4o.sNi4o.sSisPls bulk metallic glass exhibits the largest supercooled liquid region （△T = 119 K） and the highest activation energy of crystallization （283.3k J/tool）, showing enhanced glass formation ability and extraordinary glassy thermal stability.     

An Attempt to Prepare Metallic Glasses from Quasicrystals

Icosahedrons in supercooled liquids and glasses are considered to be of significance for the glass formation in alloy systems.Starting from the similarity of the local structure of quasicrystals to the icosahedrons in metallic glasses,a scheme is put forward to prepare metallic glasses based on a well-known quasicrystal Zr_(40)Ti_(40)Ni_(20).A series of(Zr_(40)Ti_(40)Ni_(20))_(100-x)Co_x metallic glasses are fabricated,and the optimized glass forming composition is determined at(Zr_(40)Ti_(40)Ni_(20))_(92)Co_8.The results show that the glass-forming ability of the alloys is closely related to the quasicrystalline phases.The mechanism of the enhanced glass-forming ability is discussed.     

集体运动态中的辛弱数混合

在由S和D核子关联对构成的原子核集体运动态中,存在由辛弱数混合造成的伪态成份. 给出了计算这种伪态成份的公式,并进行计算和讨论.     

Local Energy Statistics in Spin Glasses

Recently, Bauke and Mertens conjectured that the local statistics of energies in random spin systems with discrete spin space should in most circumstances be the same as in the random energy model. We review some rigorous results confirming the validity of this conjecture. In the context of the SK models, we analyse the limits of the validity of the conjecture for energy levels growing with the volume of the system. In the case of the Generalised Random energy model, we give a complete analysis for the behaviour of the local energy statistics at all energy scales. In particular, we show that, in this case, the REM conjecture holds exactly up to energies E _N < β _c N, where β _c is the critical temperature. We also explain the more complex behaviour that sets in at higher energies. Research supported in part by the DFG in the Dutch-German Bilateral Research Group “Mathematics of Random Spatial Models from Physics and Biology” and by the European Science Foundation in the Programme RDSES.     

高能诱发核反应中粒子产生的相对信息熵

在本实验中，引用了一个新的特征量，相对信息熵Ｒ，研究了能量为１４．６，６０，２００ＡＧｅＶ的氧离子和２００ＡＧｅＶ的硫离子诱发核反应的产生粒子多重数分布．在目前的能区中，Ｒ近似地能量无关．Ｒ对快度窗口大小依赖的饱和性，揭示了中心区的熵集中产生．实验结果与Ｌｕｎｄ模型的ＦＲＩＴＩＯＦ模拟计算的预言一致．     

Entropy of Quantum States

Given the algebra of observables of a quantum system subject to selection rules, a state can be represented by different density matrices. As a result, different von Neumann entropies can be associated with the same state. Motivated by a minimality property of the von Neumann entropy of a density matrix with respect to its possible decompositions into pure states, we give a purely algebraic definition of entropy for states of an algebra of observables, thus solving the above ambiguity. The entropy so-defined satisfies all the desirable thermodynamic properties and reduces to the von Neumann entropy in the quantum mechanical case. Moreover, it can be shown to be equal to the von Neumann entropy of the unique representative density matrix belonging to the operator algebra of a multiplicity-free Hilbert-space representation.     

Influence of Rare-Earth Substitution for Iron in FeCrMoCB Bulk Metallic Glasses

The effects of rare earth addition on the glass forming ability of Fe50-xCr15Mo14C15B6Mx （x =0, 2 and M=Y, Gd） bulks and ribbons are studied. The thermal and structural properties of the samples are measured by a combination of differential scanning calorimetry （DSC）, x-ray diffraction and scanning electron microscopy. Chemical compositions are checked by energy dispersive spectroscopy analysis. The copper mold casting technique leads to a fully amorphous structure up to 2mm only for compositions containing Y or Gd. In the case of ribbons, a fully amorphous phase is observed for all the compositions. The roles of Y and Gd are discussed on the basis of melting behavior analyzed by high-temperature DSC. Such elements act as oxygen scavengers, avoiding heterogeneous nucleation.     

Compression Behaviour of Bulk Metallic Glasses and Binary Amorphous Alloy

The compression properties of Zr41Ti14Cu12.aNi10Be22.5, Zr44.4Nb7Cu13.5Ni10.8Be24.3 bulk metallic glasses and Ni77P23 binary amorphous alloy are investigated at room temperature up to 24 GPa, 39 GPa and 30.5 GPa, respectively, using in-situ high pressure energy dispersive x-ray diffraction with a synchrotron radiation source. The pressure-volume relationship of Ni77P23 amorphous alloy is consistent well with the second order BirchMurnaghan （B-M） equation within the experimental pressure range. However, under higher pressure, the experimental data of Zr-based specimens deviate from the B-M equation. Compare to the binary amorphous alloy less excess free volume existing in the bulk metallic glass and multi-component atomic configuration results in a two-stage relationship between compressibility and pressure.     

Recent Advancements in Bulk Metallic Glasses and Their Applications: A Review

Bulk metallic glasses (BMGs), that display extraordinary properties of high strength, corrosion resistance, polymer-like formability, and excellent magnetic properties, are emerging as modern quintessential engineering materials. BMGs have garnered significant research enthusiasm owing to their tremendous technological and scientific standing. In this article, the recent advancements in the field of BMGs and their applications are put in a nutshell. Novel state-of-the-art production routes and nano/microimprinting strategies with salient features capable of circumventing the processing related complexities as well as accelerating modern developments, are briefly summarized. Heterogeneous BMG composite systems that lead to incredible combination of otherwise conflicting properties are highlighted. Biocorrosion studies and recent developments in the field of magnetic BMGs are presented owing to their significance for prospective biomedical and magnetic applications, respectively. In the last section, the current status of BMGs applications in the field of catalysis, biomedical materials, structural materials, functional materials, microelectromechanical systems (MEMS), and micro/macro devices are summed up.     

Configuration Mixing of Quark States in Baryons

Mixing angles are used to describe the SU(6) ? O(3) symmetry breaking in [70, 1^?] multiplet in the sector of the lowest mass nucleon resonances, which are investigated extensively in constituent quark models for baryon spectroscopy. The transition amplitudes for the meson photoproduction off nucleon can also be expressed in terms of the mixing angles to take into account the configuration mixing. Those amplitudes are derived as a function of the mixing angles between ${|N^2P_M{J}^-\rangle}$ and ${|N^4P_M{J}^-\rangle}$ states, with J = 1/2 and 3/2, for the processes γp → ηp, K ⁺ Λ, K ⁺ Σ ^°, K ^° Σ ⁺. The present status of our knowledge on the mixing angles between S ₁₁(1535) and S ₁₁(1650) (θ _S ), as well as between D ₁₃(1520) and D ₁₃(1700) (θ _D ) is reported. Since these resonances play very important role in the threshold region for both η and kaon production mechanisms, they are expected to provide crucial tests of different quark models for the baryon spectroscopy.     

Nanosphere Templated Metallic Grating Assisted Enhanced Fluorescence

In this paper, enhanced fluorescence from a silver film coated nanosphere templated grating is presented. Initially, numerical simulation was performed to determine the plasmon resonance wavelength by varying the thickness of the silver film on top of a monolayer of 400 nm nanospheres. The simulation results are verified experimentally and tested for enhancing fluorescence from fluorescein isothiocyanate whose excitation wavelength closely matches with the plasmon resonance wavelength of the substrate with 100 nm silver film over nanosphere. The 12 times enhancement in the intensity is attributed to the local field enhancement in addition to the excitation of surface plasmon polaritons along the surface.     

Glass Forming Ability of Metallic Glasses Evaluated by a New Criterion

The glass-forming ability （GFA） of Cu-Zr binary alloys is evaluated using the existing criteria based on calorimetric parameters, and poor relations are found. Therefore, another parameter Tτκ defined as Tκ/Tl, in which Tκ is the Kauzmann temperature and Tl the equilibrium liquidus temperature, is proposed. It exhibits good agreements with the experimental data of the Cu-Zr system and other representative bulk metallic glass formers so long as classifying them into strong or fragile category. It is suggested that kinetic effects are irrelevantly incorporated in the GFA analysis in the previous work.     

高能多粒子末态的多重分形维数与动力学起伏强度

研究了多重分形维数与动力学起伏强度的关系,给出了一个能直接描述高能多粒子末态动力学起伏强度的特征参量,并指出了这一参量的适用范围以及在实际高能实验中的应用.