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The Quantum Hall Plateau-to-Plateau transition is a long-standing problem that has not yet been solved. Around the critical point, very different critical exponents of the localization length have been gotten experimentally. We approach this problem by doing experiments in the alloy disorder, which is realized in the Al_xGa_1-xAs-Al_0.32Ga_0.68As heterostructure. By measuring directly the alloy scattering rate, we found the alloy disorder to be strong (1.13eV), short-range (atomic size) and temperature-independent3. By controlling the Aluminum concentration x, we make systems dominated by the short-range alloy disorder, where quantum mechanics prevails. In these systems, the scaling exponent is observed to be 0.42.

Using a density functional approach calculation, the structural and electronic properties of Mg₈Ni₅, Mg₈Ni₄Al, Mg₈Ni₄Ca and Mg₈Ni₄Mn clusters are investigated. The Al-, Ca-, Mn-doping in MgNi clusters lengthen $d_{\mathrm{\text{(Mg–Ni)}}}$, also increase the Mulliken charge, and improve magnetic moment on most shell atoms, so that the doping is helpful for hydrogen storage. The reaction heats of hydrogenation, the enthalpies of formation, the desorption energies show that the Mg₈Ni₄Mn, Mg₈Ni₅, Mg₈Ni₄Al clusters have a good property of hydrogen storage materials with relatively higher reaction heat of hydrogenation, and that their hydrides have a smaller desorption energy. So the Mg₈Ni₄M (M = Ni, Al, Ca, Mn) clusters are some preferred candidates of H storage. These results indicate the advantage of small size and suitable metal-doped MgNi clusters on hydrogenation and dehydrogenation.

Particle coalescence has wide applications in nature and industry. In this study, molecular dynamics (MDs) simulations were employed to examine the sintering of Cu and Au nanoparticles, as well as two other systems, namely, Cu nanoparticles and Au nanoparticles. The results suggested that, the Au atoms diffused through the outer area of the sintering neck before the nanoparticles were fused into one sphere. The possible reason was that the Au atoms resembled fluid, which could be ascribed to the local thermal energy at the contact area. Typically, the change in energy per atom from 300 K to the contact temperature denoted that less energy was required for the atoms in the pure Cu system to contact with each other than those in the other two systems.

The MCrAlY bonding layer alloy was prepared by vacuum melting, and the alloy composition was NiCoCrAlY and NiCoCrAlYHfTa. The high-temperature cyclic oxidation experiment was carried out in air at 1050^∘C until it failed. The results show that Hf and Ta have a significant influence on the oxidation resistance of the alloy. The doped specimens have longer oxidation lifetimes compared to the undoped samples. The study also found that the Hf would diffuse out and combine with O to form HfO₂ in the thermally grown oxide (TGO) layer, which would improve the adhesion and reduce the wrinkles of the oxide layer. Ta in the doped specimens hinders the diffusion of Al and reduces the oxidation rate, while improving the thermal mismatch. Therefore, the specimens doped with both Hf and Ta have the highest oxidation lifetimes, though the oxidation lifetime was 10 times longer than that of the undoped specimens. It is indicated that the doping of Hf and Ta is an important method to improve the oxidation lifetime of thermal barrier coatings (TBCs).

Eleven types of the equation of state (EOS) are compared and classified into two groups, linear EOS and exponential EOS. The qualities of these two EOS groups are then verified with the data of 50 alloys. Through the comparison, it is found that the exponential Li equation gives a more reliable result when the fitting energy versus volume points are scattered in a wide scale or have a large number of data to fit. However, when the fitting data concentrate is in a small area near the equilibrium point, the linear four-parameter Birch–Murnaghan EOS has a better fitting result. Moreover, it is found that the Li equation has the best performance among these exponential EOSs with the smallest fitting errors. Additionally, there is a correlation found to be (P_C/B₀)/[(V_C/V₀)/V₀] ≈ 0.3087 between ultimate strength P_C and critical volume V_C for the stable phases among the studied alloys.

The electronic packaging and systems are very important topics as the limitation of miniaturization approaches in semiconductor industry. Regarding the optimal materials microstructure for these applications, we studied different alloys such as Sn-3.0Ag-0.5Cu (wt.%)/organic solderability preservative (SAC305/OSP) Cu and SAC305–0.05Ni/OSP Cu solder joints. We implemented the fractal dimension characterization and microstructure morphology reconstruction. This is the first time that we applied fractals on such alloys. The morphology reconstruction is important for predicting and designing the optimal microstructure for the advanced desirable properties these alloys. These analyzed parameters are important for the hand-held devices and systems especially for the exploitation. The fractal reconstruction was applied on the prepared microstructures with five different magnifications. The results confirmed successful application of fractals in this area of materials science considering the grains and shapes reconstructions.

The oxidation of the single crystal stepped Pt₃Ti(510) surface at oxygen pressures below 10^-5 mbar and at a temperature of 770 K was studied by means of X-ray photoelectron spectroscopy (XPS), low energy ion scattering (LEIS) and low energy electron diffraction (LEED). Scanning tunneling microscopy (STM) was used to follow the evolution of the surface morphology on the atomic scale. The clean surface studied in ultrahigh vacuum conditions was found by LEIS to be composed of platinum only in the outermost surface plane. LEED and STM indicate that the clean Pt₃Ti(510) surface consists of (100) terraces separated by double atomic steps. The exposure of the clean surface to oxygen at pressures in the range of 10^-7–10^-5 mbar leads to the growth of a titanium oxide layer (with a composition close to TiO) which covers completely the substrate surface. The TiO film has long range order and exhibits complex LEED patterns. The STM measurements indicate that the ordered array of steps is kept in the early stages of the oxide film growth, whereas a change of the step morphology and step orientation is observed during the oxidation process.

The present study was focussed on investigating the corrosion properties of plasma-oxidized and -nitrided CoCrMo alloys under different conditions. The structural properties of untreated and treated samples were examined by using scanning electron microscopy (SEM) and X-ray diffraction (XRD). Corrosion behavior of samples was mainly investigated by potentiodynamic polarization and electrochemical impedance spectroscopy in simulated body fluid solution. The results showed that corrosion resistance of the oxidized layers was better than that of the nitrided ones. The corrosion resistance of the alloys increased as the plasma oxidation process temperature and time increased. However, the corrosion resistance of the alloys reduced with increase in the process temperature and time after plasma nitriding process.

In this paper, a high-throughput droplet method is presented for screening corrosion inhibitors, particularly for those metals that are subjected to pitting. To this objective, AA5083 was used as a case study as it is subject to pitting corrosion in saline solution containing different corrosion inhibitors. This paper outlines how critical parameters are measured and calculated (average pit depth and maximum pit depth) and the errors and consistency of the method, and the definition of corrosion inhibition via the method. The results from this method were then compared to the results of inhibition efficiency derived from potentiodynamic polarization scans for inhibitors with a range of performance. The method was conducted at temperature $T=22\pm 2^{\circ }$C inside a humidity chamber, and concentration 10${}^{-3}$ M of seven chemical compounds that have similarities in their structures. The discrepancies were profound for the cases where the inhibitor was of low efficiency, which is ascribed to the fact that these pits’ growth is dominated by that of a few large pits.

Development of agent systems is without question a complex task when autonomous, reactive and proactive characteristics of agents are considered. Furthermore, internal agent behavior model and interaction within the agent organizations become even more complex and hard to implement when new requirements and interactions for new agent environments such as the Semantic Web are taken into account. We believe that the use of both domain specific modeling and a Domain-specific Modeling Language (DSML) may provide the required abstraction and support a more fruitful methodology for the development of Multi-agent Systems (MASs) especially when they are working on the Semantic Web environment. Although syntax definition based on a metamodel is an essential part of a modeling language, an additional and required part would be the determination and implementation of DSML constraints that constitute the (formal) semantics which cannot be defined solely with a metamodel. Hence, in this paper, formal semantics of a MAS DSML called Semantic Web enabled Multi-agent Systems (SEA_ML) is introduced. SEA_ML is a modeling language for agent systems that specifically takes into account the interactions of semantic web agents with semantic web services. What is more, SEA_ML also supports the modeling of semantic agents from their internals to MAS perspective. Based on the defined abstract and concrete syntax definitions, we first give the formal representation of SEA_ML's semantics and then discuss its use on MAS validation. In order to define and implement semantics of SEA_ML, we employ Alloy language which is declarative and has a strong description capability originating from both relational and first-order logic in order to easily define complex structures and behaviors of these systems. Differentiating from similar contributions of other researchers on formal semantics definition for MAS development languages, SEA_ML's semantics, presented in this paper, defines both static and dynamic aspects of the interaction between software agents and semantic web services, in addition to the definition of the semantics already required for agent internals and MAS communication. Implementation with Alloy makes definition of SEA_ML's semantics to include relations and sets with a simple notation for MAS model definitions. We discuss how the automatic analysis and hence checking of SEA_ML models can be realized with the defined semantics. Design of an agent-based electronic barter system is exemplified in order to give some flavor of the use of SEA_ML's formal semantics. Lessons learned during the development of such a MAS DSML semantics are also reported in this paper.

Our present work deals with the formation and thermal behavior of a nonbulk alloy phase confined within about 8 nm across the interfaces of Au/Cu multilayer systems. These multilayers deposited on silicon and float glass by DC magnetron sputtering have been studied by secondary ion mass spectrometry (SIMS), X-ray diffraction (XRD) and cross-sectional transmission electron microscopy (XTEM). Along with the highly oriented growth of the Cu and Au layers along [111], Cu₃Au alloy was found to be present only at the Cu/Au interfaces in the nonbulk tetragonal D0₂₃ phase. Co-sputtering of Au and Cu under similar conditions produces only conventional fccCu₃Au alloy phases, suggesting that interfacial confinement plays a significant role in producing the novel Cu₃Au alloy phase in gold/copper multilayers. This novel phase is found to form only when the interfacial width is less than 10 nm. The D0₂₃ alloy phase tends to stabilize, rather than transforming to the bulk L1₂ phase, when the multilayer is vacuum-annealed at 150°C. As alloy formation spreads out of the interfaces (on vacuum annealing at 200°C), the dominant alloy is CuAu, consistent with the Cu:Au atomic ratio averaged over the multilayer.

The effects of relative positions of Se atoms in a monomolecular layer of MoS${}_{1.5}$Se${}_{0.5}$ have been studied. It is demonstrated that the distribution of Se atoms between top and bottom chalcogen planes is most energetically favorable. For a more probable distribution of Se atoms this monolayer alloy is a direct semiconductor with the fundamental bandgap of 2.35eV. We have also evaluated the optical band gaps of the alloy at 77K (1.86eV) and room temperature (1.80eV), which are in a good agreement with the experimentally measured bandgap of 1.79eV.

Recent developments in the field of manufacturing techniques and alloy development of light materials are reviewed. In the field of manufacturing Aluminium based components, special attention is given to casting, including liquid forging and semi-solid forming technology while for sheet metal forming technology the focus is on material properties and process technology in superplastic forming. For the manufacturing of Magnesium-based components, special attention is given to casting processes and alloy development for casting. For wrought Magnesium, material properties control is covered. For Titanium-based components, an overview of the latest additions to high strength alloys are given, including non-linear elasticity as demonstrated by materials like GUM Metal™. Advanced forming technology such as Levi Casting are also treated.

Unlike synthesis of nanowires (1D nano-objects) the synthesis of nanoplatelets (2D nano-objects) has not been performed frequently. Herein, we report on the synthesis of Cu–Ge based on nanoplatelets with a high surface-to-volume ratio prepared by low pressure chemical vapor deposition (LPCVD) of Ge₂Me₆ and a mixture of Ge₂Me₆/PbEt₄. Nanostructured deposits are composed of Cu_1-xGe_x nanoplatelets, Ge nanowires and Ge nanoparticles. The nanoplatelets, which have the lateral size up to several tens of micrometers and thickness of 100–400 nm, belong to the cubic α phase of Cu₉₁Ge₉ alloy (Ge admixture in cubic Cu) and hexagonal ζ phase of Cu₈₅Ge₁₅ alloy. Nanowires composed of cubic Ge have a diameter of about 30 nm and length of several tens of micrometers. Lead does not enter any of these phases due to Pb–Cu and Pb–Ge immiscibility; therefore, it was observed as separate nanoparticles.

By this work, we aim to study the dynamical and the thermodynamic properties of the zinc-blende GaX (X = N, P, As and Sb) using the Ab initio simulation method. Indeed, we studied the lattice dynamics, the constant-volume specific heat (Cv), the internal energy (U), the entropy (S) and the free energy (F). The observed differences between the properties of GaX elements were discussed. Our results and the available literature data (theoretical and experimental) seems to be in good agreement. Moreover, Cv, U, F and S were calculated by using the harmonic approximation in the calculation of the dynamic lattice vibration. The good agreement between our results of both the phonon frequency, the constant-volume specific heat and the experimental data allows us to conclude that our results of S, U and F of GaX were well predicted.

The Quantum Hall Plateau-to-Plateau transition is a long-standing problem that has not yet been solved. Around the critical point, very different critical exponents of the localization length have been gotten experimentally. We approach this problem by doing experiments in the alloy disorder, which is realized in the Al_xGa_1−xAs-Al_0.32Ga_0.68As heterostructure. By measuring directly the alloy scattering rate, we found the alloy disorder to be strong (1.13eV), short-range (atomic size) and temperature-independent3. By controlling the Aluminum concentration x, we make systems dominated by the short-range alloy disorder, where quantum mechanics prevails. In these systems, the scaling exponent is observed to be 0.42.

Magnesium alloys still have a lot of technical challenges to be solved for more applications. There have been many research activities to enhance formability of magnesium alloys. One is to design new alloy composition having better formability. Also, low formability of wrought alloys can be improved by optimizing the processing variables. In the present study, effect of process variables such as forging temperature and forging speed were investigated to forgeability of three different magnesium alloys such as AZ31, AZ61 and ZK60. To understand the effect of process variables more specifically, both numerical and experimental works have been carried out on the model which contains both upsetting and extrusion geometries. Forgeability of magnesium alloys was found to depend more on the forging speed rather than temperature. Forged sample showed a significant activity of twinning, which was found to be closely related with flow uniformity.