Three-layer Phase Research Articles

Study on the Effect of Microstructures and Properties of Al-Mg-Mn-Zr Alloy Welding Wire by Adding Minor Sc

The low strength of welded joints of aluminum alloy welding wire materials has seriously restricted the promotion and application of high-performance aluminum alloys represented by 7A52 and 7B52 aluminum alloy. It is urgent to develop new high-strength aluminum alloy welding wire material to meet the lightweight application demand of 7××× series high-performance aluminum alloy materials in military and civilian vehicles. This paper studied the effect on microstructures, mechanical properties, and welding properties of Al-6Mg-0.3Mn-0.2Zr welding wire alloys by adding minor Sc elements. The result shows that it formed Al3Zr, Al3Sc, and Al3(Sc1-x, Zrx) primary dispersive phases in the matrix, and the Al3(Sc1-x, Zrx) primary phase, which had triple-shell microstructure composed of Al3Zr/α(Al)/Al3Sc three-layer phases enclosing individually with each other from the center to outside. These phases could promote heterogeneous nucleation during solidification and crystallization in the process of welding, resulting in strong refinement and strengthening effects in the weld-zone microstructure. The welding joint mechanical properties of both tensile strength and elongation increased with the increase of Sc contents within the range of 0–0.4%. It was reached at Rm 365 MPa/A 5% without means of heat treatment which are much higher than aluminum alloy welding wires used in current engineering when the 7B52 aluminum alloy laminated plates were welded with the prepared welding wire Al-6Mg-0.3Mn-0.2Zr alloys of 0.385% Sc.

Dynamic simulation and techno-economic analysis of liquid air energy storage with cascade phase change materials as a cold storage system

Liquid air energy storage (LAES) is a promising solution for overcoming the challenge of intermittency in renewable-based energy systems. Cold recovery is the most important part of the LAES and plays a vital role in the performance of the system. In this study, the LAES system which utilizes a packed bed thermal energy storage (PBTES) comprising three-layer phase change materials (PCM) is investigated from a thermodynamic and economic point of view. As a result of the transient nature of PBTES the dynamic modeling is applied to analyze the performance of the system. The designed LAES system with ideal condition consumes 4.42 MWh for compressing the air and generates 1.8 MWh of electricity during the peak time. The payback period of the system for the case study of San Fransico is 6.7 years with 0.66 M$ total profit. As a dynamic behavior of the system liquid yield, the mass flow rate of liquid air, the specific work of the compressors, and the cryo turbine vary during different cycles. After about 22 cycles system with a total efficiency of 42.5% reaches the equilibrium and the performance of the system decrease about 5.9% because of transient behavior in comparison with the ideal cycle.

Resonant x-ray scattering observation of transitional subphases during the electric-field-induced phase transition in a mixture of Se-containing chiral smectic liquid crystals.

Using resonant x-ray scattering techniques, transitional subphases during the electric-field-induced phase transition of a mixture of Se-containing chiral liquid crystals, 80% AS657 and 20% AS620, in a planar-aligned cell geometry were investigated, where the prototypical phase sequence SmC_{A}^{*}-SmC_{γ}^{*}-AF-SmC^{*} was observed; the transitional subphases were formed during the transition from the three-layer periodicity phase to the ferroelectric phase. In the lower-temperature range where the three-layer SmCγ^{*} phase appeared under the low electric field, nine- and six-layer subphases and a "streak" pattern appeared in sequence after the transition from the SmCγ^{*} phase with increasing applied electric field; the ferroelectric phase was realized. In the higher-temperature range where the four-layer AF phase appeared under a low electric field, the AF phase changed to a three-layer phase at the medium electric field. The twelve-, nine-, and six-layer subphases subsequently appeared in sequence, and finally the ferroelectric phase was generated with increasing electric field. The molecular arrangements of the field-induced subphases, especially the newly found nine-layer periodicity phase, was analyzed. The successive field-induced phase transition of the present results was compared with that of our previous results for pure Se-containing and Br-containing liquid crystals, and the relation to the three-layer ferrielectric phase was discussed.

Multigap superconductivity in doped p-type cuprates

Andreev and tunneling spectroscopy studies of Bi2Sr2Can − 1CunO2n + 4 + δ, HgBa2Can − 1CunO2n + 2 + δ and Tl2Ba2Can − 1Cu2n + 4 + δ have shown that superconductivity in single-layer (n = 1) and two-layer (n = 2) phases has a single-gap character. Qualitatively different results were obtained for three-layer phases. In doped p-type Hg-1223, Bi-2223, and Tl-2223 samples two (or three) superconducting gaps were observed. The existence of multigap superconductivity in superconducting cuprates with n ≥ 3 is explained by a difference in doping levels of outer (OP) and internal (IP) CuO2 planes.

A tunable three layer phase mask for single laser exposure 3D photonic crystal generations: bandgap simulation and holographic fabrication

Through the use of a multi-layer phase mask to produce five-beam interference, three-dimensional photonic crystals can be formed through single exposure to a photoresist. In these holographically formed structures, the interconnectivity is controlled by the relative phase difference among contributing beams. Photonic band gaps are calculated and the simulation shows a maximum bandgap of 18% of the middle gap frequency when the phase difference is optimized. A three-layer phase mask is fabricated by placing a spacer layer between two orthogonally-orientated gratings. The phase difference is controlled by thermal-tuning of the spacer thickness. Photonic crystal templates are holographically fabricated in a photosensitive polymer using the phase mask.

Plane Poiseuille Flow of Two Compatible Polymers: Influence of the Interphase on the Flow Stability

This paper deals with coextrusion flows of two compatible polymers which are known to be generally more stable than the same flows of incompatible systems. We show that the weak response to disturbance of such flows can be predicted by considering an interphase of nonzero thickness (corresponding to an interdiffusion zone) instead of a purely geometrical interface between the two layers. As a first step we try to explain the weak sensibility to disturbance of compatible systems by the sole presence of this intermediate layer. For that purpose we study the linear stability response to very long waves of a three-layer phase Poiseuille flow with an inner thin layer which represents the interphase. Although this fact is an approximation, it nevertheless takes into account the diffusion phenomena which are generated in the interphase. This first approach (corresponding to a reduction in the effective viscosity ratio) is shown to explain the diminished growth rates but not the reduction in the size of the unstable region. As a second step, we formulate an energetic approach of the problem. We evaluate the energy dissipated during the interdiffusion process and the variation of kinetic energy of the global system. A modified growth rate is then determined by taking into account the energy dissipated by the interdiffusion process. This lower growth rate enables us to explain the increase of the stable domain in the case of compatible polymeric systems.

Oxygen loading in (Bi,Pb)-2212 and -2223 materials

Carrier doping arising from oxygen loading and Pb substitution in (Bi,Pb)-2212 and -2223 polycrystalline materials has been monitored using thermopower and T c for a range of annealing conditions in which oxygen partial pressure and temperature are carefully controlled. The three-layer compound shows a departure from the common thermopower-doping relationship found for other superconducting cuprates. This can be interpreted in terms of a hole-concentration deficiency on the inner Cu–O layer for underdoped samples. Activation energies for oxygen loading are derived for the two- and three-layer phases; these decrease as Pb content is increased, in the case of Bi-2212 by a factor of two from 0.25eV for the Pb-free material. The maximum doping level is only weakly dependent on Pb content, however. This reflects both a decrease in oxygen content with increasing Pb concentration, and a buffering action by phase decomposition at higher oxygen partial pressures. At low oxygen content there is a net increase in doping with Pb substitution, so that the doping range accessible through oxygen loading and unloading becomes increasingly restricted as Pb content increases. The carrier doping equilibria also appear to have a very low dependence on oxygen partial pressure, further evidence that a simple vacancy model for hole doping via oxygen loading is not adequate for these materials.

Maxwell displacement current due to phase transitions in liquid crystals on a water surface

The phase transitions of Langmuir films of the liquid crystals (LCs) 4′-n-pentyl-4-cyano-biphenyl (5CB), 4′-n-octyl-4-cyano-biphenyl (7CB), 4′-n-octyl-4-cyano-biphcnyl (8CB) and 4′-n-decyi-4-cyano-biphenyl (10CB), have been investigated by a Maxwell displacement current (MDC) measuring technique, A phase transition of LC molecules from the planar surface alignment phase to the polar one was clearly detected in the range of low surface pressures during monolayer compression. A phase transition between a stable monolayer phase and a stable three-layer phase of the liquid crystal film was detected during further monolayer compression.

Detection of phase transitions in liquid crystals on a water surface by a Maxwell displacement current-measuring technique

The phase transitions of Langmuir films of liquid-crystal 4-cyano-4′-5-alkyl-biphenyl (5CB), 4-cyano-4′-7-alkyl-biphenyl (7CB), 4-cyano-4′-8-alkyl-biphenyl (8CB), and 4-cyano-4′-10- alkyl-biphenyl (10CB) were investigated by a Maxwell displacement current (MDC)-measuring technique. A weak first-order phase transition of the orientation of LC molecules from the isotropic phase to the polar one was clearly detected by compressing the film in the range of immeasurably low surface pressure by means of the technique. For further compression, a first-order phase transition between a stable monolayer phase and a stable three-layer phase of the liquid crystal film was detected. The result shows that the MDC-measuring technique is useful in the detection of phase transitions over the entire range of molecule areas.

Processing of thin films of the three-layer superconducting phase in the Pb-doped Bi-Sr-Ca-Cu-O system by metalorganic deposition

Thin films of the three-layer phase in the Pb-doped Bi-Sr-Ca-Cu-O system have been processed from metalorganic precursors by spin pyrolysis. The cation composition of the three-layer phase was found to differ significantly from the stoichiometric “2-2-2-3” composition. Superconductive measurements suggest a distribution of distinct regions with different T c within a pure three-layer thin film. Temperature-time-transformation studies were carried out on the three-layer phase in air showing the narrow temperature range of stability.

In situ quenching process and properties of Bi-Sr-Ca-Cu-O superconducting thin films by magnetron sputtering

As-grown crystallized superconducting thin films of Bi-Sr-Ca-Cu-O have been prepared on MgO (100) at 700 degrees C by DC magnetron sputtering using a single target. The as-grown process, followed by quenching, yielded c-axis oriented superconducting thin films with smooth surfaces. These films displayed the three-layer phase with a c-axis lattice constant of about 37 AA. Although the superconducting properties of the films were very sensitive to the oxygen pressure during the quenching process, reproducible results were obtained. The best film showed zero resistivity at 81 K and the critical current density increased from 8*104 A cm-2 at 77 K to 3*106 A cm-2 at 4.2 K.

Cation chemistry and phase relations in the superconducting Bi-Pb-Ca-Sr-Cu-O system

The cation chemistry and magnetic susceptibility of a suite of samples in the superconducting (Bi,Pb) 2Ca n −1 Sr 2Cu n O x system have been studied at various stages during their evolution from the two-layer to the high T c three-layer polytype. Relationships between phase assemblage and cation chemistry have been identified in both relatively pure and interlayered samples. The Ca/Sr ratio is an important indicator of the relative proportion of the 30 and 37 Å phases. The cation defect structure of these (Bi,Pb) 2Ca n − 1 Sr 2Cu n O x superconductors includes significant vacancies on the Bi and possibly the Sr layers. High cation vacancy concentrations, particularly in the two-layer-dominant material formed at early stages in processing, may play a key role during the subsequent two-layer → three-layer phase transformation.

Hydration-phase diagrams and friction of montmorillonite under laboratory and geologic conditions, with implications for shale compaction, slope stability, and strength of fault gouge

Absorption of water into the crystal structure of smectite clays causes a reversible volume increase exceeding 80% and a friction decrease by a factor of three. This behavior can be predicted if clay swelling is approximated as the formation of successive hydration phases and the generalized Clapeyron law is applied. In this study, new data on two standard montmorillonites saturated with sodium and calcium (Na-MM and Ca-MM) are combined with published results to define relative humidity boundaries of proposed phases at 20°C and 1 bar. From molar volumes, the effect of confining pressure is predicted; only phases with an integral number of full interlaminar water layers are stable at high pressures. In contact with liquid water, the number of interlaminar layers is governed by the “effective normal stress” on crystals. Next, vapour pressure measurements at 20°–60°C are used to calculate dehydration enthalpies, from which the effect of geologic temperatures is predicted. Under typical crustal conditions, Na-MM does not fully dehydrate until 7 km depth, and Ca-MM retains one water layer to 11 km. Since the zones of hydrocarbon maturation and montmorillonite dehydration overlap, this effect may play a part in petroleum geology, controlling migration and/or reservoir pressurization. For the first time, the friction of individual hydration phases of montmorillonite has been measured without excess water and within their stability fields. Stable-sliding deformation with negligible rate-dependence and definite work-hardening is observed, but the pressure-dependence is less than in classical friction. Na-MM phases are always weaker than their Ca-MM analogues. In both clays, the addition of the first water layer causes the greatest strength decrease, but two- and three-layer phases are successively weaker. The friction coefficient of three-layer Na-MM at low pressure is near 0.27, consistent with most observed bedding plane rockslides in shales. If Ca-MM is abundant in fault gouge, average friction in the top 10 km of strike-slip and normal faults may be as low as 0.34. Such weak faults would permit major deformation of continental crust by regional shear stresses as low as 27 MPa. This model would also explain the frequent reactivation of ancient faults by later stresses of diverse orientations.