scholarly journals Dissimilar Metal Solution from Solid Alloys as Observed for Steels and Nickel‐Based Alloys in the Presence of Lead‐Based Liquid Alloys or Liquid Tin

JOM ◽  
2021 ◽  
Author(s):  
Carsten Schroer
Keyword(s):  
Alloy Composition ◽  
Formation Mechanisms ◽  
Liquid Alloys ◽  
Selective Leaching ◽  
Depletion Zone ◽  
Initial Stage ◽  
Characteristic Features ◽  
Solid Alloys ◽  
Liquid Tin ◽  
Process Characteristic

AbstractThe solution of elements from metallic alloys is analyzed, notably the initial stage characterized by solution in proportion to the alloy composition and subsequent selective leaching of alloying elements. For the latter stage of the process, characteristic features of the originating depletion zone are derived for different formation mechanisms. The results are compared with observations for steels and nickel-based alloys after exposure to lead-based liquid alloys or liquid tin, and, where possible, the prevailing mechanism is identified. Furthermore, the influence of dissolved oxygen and formation of intermetallic compounds are addressed.

STRUCTURAL AND ELECTRONIC PROPERTIES OF THE Li/Si(001) SURFACE

1996 ◽  
Vol 03 (03) ◽  
pp. 1487-1494
Author(s):  
J.W. CHUNG
Keyword(s):  
Electronic Properties ◽  
Binding Sites ◽  
Room Temperature ◽  
Structural Models ◽  
Metallic Phase ◽  
Surface Band ◽  
Ordered Structures ◽  
Initial Stage ◽  
Structural And Electronic Properties ◽  
Characteristic Features

Atomic arrangements and electronic properties of the Li-adsorbed Si(001) surface are briefly reviewed. Characteristic features of a series of ordered structures with increasing Li coverage at room temperature are described. Structural models invoking a dimer flipping mechanism are discussed for the first two ordered structures, (2×2)-Li and (2×1)-Li, which are proposed as reconstructions of the silicon substrate. It is shown that the metallic phase found at an initial stage of adsorption is a result of substrate metallization, which explains the presence of an intraband surface plasmon. The features of the surface band structures for the first two ordered structures are discussed in terms of variation of the binding sites with coverage. All the unique features of the Li/Si(001) surface essentially exhibit the size effects of Li.

Interaction of Components of Co-Sn and Co-Sn-Cu Powder Materials in Liquid Phase Sintering

2019 ◽  
Vol 943 ◽  
pp. 113-118
Author(s):  
Evgeniy Georgiyevich Sokolov ◽  
Alexander Vitalyevich Ozolin ◽  
Lev Ivanovich Svistun ◽  
Svetlana Alexandrovna Arefieva
Keyword(s):  
Liquid Phase ◽  
Solid Phase ◽  
Steel Substrate ◽  
Liquid Phase Sintering ◽  
Powder Materials ◽  
Cu Alloys ◽  
Initial Stage ◽  
Interaction Of Components ◽  
Sintered Alloys ◽  
Liquid Tin

The interaction of components and structure formation were studied in liquid phase sintering of Co-Sn and Co-Sn-Cu powder materials. The powders of commercially pure metals were mixed with an organic binder and applied on the steel substrate. Sintering was performed under vacuum at temperatures of 820 and 1100 °C. The structure of sintered alloys was investigated by X-ray diffractometry and electron probe microanalysis, and microhardness (HV0.01) of the structural components was measured. It has been found that the nature of interaction of the liquid tin with the solid phase at the initial stage of sintering affects the formation of structure and porosity of Co-Sn and Co-Sn-Cu alloys considerably. In Co-Sn alloys, diffusion of tin into cobalt particles leads to the formation of intermetallic compounds, which hinders spreading of the liquid phase. This results in a porous defect structure formed in Co-Sn alloys. In Co-Sn-Cu alloys, at the initial stage of sintering the liquid phase enriched with copper is formed that wets the cobalt particles and contributes to their regrouping. As a result of this, materials with minor porosity are formed.

Sign Systems in Design in the Context of Innovative Methods of Teaching

ART Space ◽  
2018 ◽  
pp. 117-119
Author(s):  
Alla Polishchuk
Keyword(s):  
Teaching Methods ◽  
Educational Process ◽  
Innovative Teaching ◽  
Innovative Methods ◽  
Sign Systems ◽  
Characteristic Features ◽  
Process Characteristic

The article deals with sign systems in design in the context of innovative teaching methods that are used in the system of modern educational process. Characteristic features of means of sign systems, forms and methods of innovative teaching are determined, the specifics of their use are revealed.

Modeling the Initial Stage of Crosslinked Aromatic Hydrocarbon Polymer Pyrolysis

2012 ◽  
Author(s):  
Tapan Desai ◽  
John Lawson ◽  
Pawel Keblinski
Keyword(s):  
Aromatic Hydrocarbon ◽  
Formation Mechanisms ◽  
Space Vehicles ◽  
Reactive Molecular Dynamics ◽  
Initial Stage ◽  
Hydrocarbon Polymers ◽  
Hydrocarbon Polymer ◽  
Polymer Pyrolysis ◽  
Commercial Applications ◽  
Dynamics Simulations

Ablative materials are employed as thermal insulators in hypersonic space vehicles and for fire proofing in commercial applications. However, the chemical reactions involved in the transformation of ablative materials to char during pyrolysis are not well understood. Reactive molecular dynamics simulations were performed to study the initial stage of the pyrolysis of crosslinked aromatic hydrocarbon polymers. The products formed were characterized and acetylene was found to be the primary product. The value of the activation energy for acetylene formation was estimated. The acetylene formation mechanisms were analyzed at different degrees of crosslinking and the graphitic precursor formation mechanism was studied.

Study on Amorphous Formation Ability of Al-Fe Alloy Liquids in Hot Dip Aluminizing

2010 ◽  
Vol 97-101 ◽  
pp. 642-647 ◽  
Author(s):  
Wei Zhang ◽  
Min Fan ◽  
Zhi Qiang Du
Keyword(s):  
Amorphous Alloy ◽  
Amorphous Phase ◽  
Alloy Composition ◽  
Formation Mechanisms ◽  
Alloy Sample ◽  
X Ray ◽  
Transmission Electron ◽  
Aluminized Steel ◽  
And Behavior ◽  
Alloy Liquids

The aluminized layer and the La-aluminized layer on 20 carbons steel were prepared by hot dip aluminizing method, and the microstructure and composition of the layer were investigated through scanning electronic microscopy (SEM), transmission electron microscope (TEM), X-ray diffractometer (XRD) and energy dispersive spectroscopy (EDS). The results showed that the amorphous phase was found in the surface layer of the hot dip aluminized steel. In order to study the phenomenon, the Al-Fe alloy liquids used in hot dip aluminizing were quickly solidified and slowly solidified respectively. The results showed that the amorphous phase was found in all Al-Fe alloy samples under the condition of the quick solidification. While the amorphous phase was only found in Al-Fe alloy sample with La under the condition of the slow solidification. Moreover, the pure amorphous alloy exists in the parts region of the sample, and the weight percentages of Al and Fe in pure amorphous alloy was 23: 2, and the amorphous alloy composition also contains a small quantity La. The formation mechanisms of the amorphous phase and behavior of La in the hot dip aluminized layer were also discussed.

Structural and Electrical Characterization of the Initial Stage of Physical Vapor Transport Growth of 4H-SiC Crystals

2015 ◽  
Vol 821-823 ◽  
pp. 90-95
Author(s):  
Tatsuya Takahashi ◽  
Chikashi Ohshige ◽  
Noboru Ohtani ◽  
Masakazu Katsuno ◽  
Tatsuo Fujimoto ◽  
...  
Keyword(s):  
Raman Scattering ◽  
Grown Crystal ◽  
Defect Formation ◽  
Vapor Transport ◽  
Physical Vapor Transport ◽  
Formation Mechanisms ◽  
X Ray Diffraction ◽  
X Ray ◽  
Initial Stage ◽  
Crystal Seed

Defect formation during the initial stage of physical vapor transport (PVT) growth of 4H-SiC crystals in the [000-1] and [11-20] directions was investigated by x-ray diffraction, defect-selective etching, and micro Raman scattering imaging. X-ray diffraction studies showed that the growths in the [000-1] and [11-20] directions exhibited markedly different behaviors with respect to the defect formation during the initial stage of growth. While a characteristic lattice plane bending was observed for the PVT growth along [000-1], a tilted domain structure was revealed near the grown crystal/seed interface for the growth in the [11-20] direction. Micro Raman scattering imaging revealed that nitrogen enrichment occurred near the grown crystal/seed interface and was associated with compressive stress parallel to the interface. Based on the results, the defect formation mechanisms during the initial stage of PVT growth of 4H-SiC are discussed.

scholarly journals THE IDENTITY OF THE OFFENDER AS AN ELEMENT OF THE FORENSIC CHARACTERISTIC OF THE CRIME

2020 ◽  
pp. 187-190
Author(s):  
Yu. A. Chaplynska
Keyword(s):  
Criminal Law ◽  
Criminal Behavior ◽  
Relevant Information ◽  
Scientific Article ◽  
Forensic Investigation ◽  
Criminal Offenses ◽  
Initial Stage ◽  
Crime Investigation ◽  
Characteristic Features ◽  
Investigation Process

The scientific article deals with some aspects of crime investigation. The identity of the offender is considered as an element of forensic characteristics. Investigating the identity of the offender provides the investigation with a number of additional features. The identity of the offender as an element of forensic characteristics is a set of socially significant features and attitudes that characterize a person guilty of violating the criminal law, in combination with other conditions and circumstances affecting his criminal behavior. In particular, the information about it allows to distinguish the data necessary for the organization of the most effective search of the person who committed the crime, and subsequently – its exposition, provide elimination of the causes and conditions of committing criminal offenses and their recidivism. And during the conduct of investigative (search) actions – the possibility of effective establishment of psychological contact, the use of appropriate tactical techniques. In order to construct an effective forensic characteristic, elements must be identified that have a clear investigative focus and can help determine further directions of the investigation. Therefore, it is indisputable to distinguish in the structure of forensic characteristics of crimes such component as the person of the offender. By identifying its characteristic features, it becomes possible to build versions at the initial stage of the investigation, to use certain tactical techniques in the course of procedural actions. A forensic investigation of an individual consists of establishing forensically relevant information about the offender and other participants in the investigation process. Investigation of the identity of the offender as an element of forensic characteristics, allows to accumulate in the portrait of the likely offender his characteristic features. Creating a forensic portrait is important enough for the whole investigation process. In any case, it allows you to put forward certain versions and search for the person who disappeared from the scene, as well as the possibility of qualitative procedural actions.

Particle-shape control and formation mechanisms of hydrothermally derived lead titanate

1999 ◽  
Vol 14 (3) ◽  
pp. 866-875 ◽  
Author(s):  
Jooho Moon ◽  
Melanie L. Carasso ◽  
Henrik G. Krarup ◽  
Jeffrey A. Kerchner ◽  
James H. Adair
Keyword(s):  
Lead Titanate ◽  
Particle Shape ◽  
Shape Control ◽  
Intermediate Phase ◽  
Solubility Diagram ◽  
Particle Morphology ◽  
Formation Mechanisms ◽  
Initial Stage ◽  
Excess Lead ◽  
Alkaline Conditions

Phase-pure perovskite lead titanate with various morphologies has been synthesized by a hydrothermal method at 150 °C. Particle shapes include cubic, tabular, and aggregated platelike shapes. The feedstock concentration greatly influences particle morphology of the hydrothermally derived PbTiO3. At a concentration of 0.05 M, the tabular particles form while cubic particles are produced at 0.1 M. Aggregated plateletlike particles are synthesized at 0.125 M. It was observed that both tabular and cubic particles directly precipitate from the coprecipitated precursor gel. In contrast, the plateletlike shaped intermediate phase appears during the initial stage of reaction at 0.125 M and in situ transforms into perovskite PbTiO3 during further hydrothermal treatment. The intermediate phase preserves its particle shape during transformation and, acting as a template, gives rise to the final tabular PbTiO3 particles. It is demonstrated that only base reagents such KOH and NaOH, which provide a highly basic condition (i.e., pH > 14), promote transformation of the coprecipitated gel into the perovskite PbTiO3. A Hancock and Sharp kinetic analysis in conjunction with microstructural evidence suggests that the formation mechanism is dissolution and recrystallization in which the degree of supersaturation plays an important role in dictating the crystallographic particle phase and morphology of the particles. An experimentally constructed solubility diagram indicates that an excess lead condition is necessary to compensate for loss of lead species and to increase supersaturation to expedite precipitation of PbTiO3 at highly alkaline conditions.

The Political Reliability of Italian Governments: An Exponential Survival Model

1984 ◽  
Vol 78 (2) ◽  
pp. 318-337 ◽  
Author(s):  
Claudio Cioffi-Revilla
Keyword(s):  
Half Life ◽  
Survival Model ◽  
The Political ◽  
Breakdown Rate ◽  
Italian Government ◽  
Characteristic Features ◽  
Process Characteristic

Italian cabinets (governi) fall from power in a seemingly haphazard pattern, thus defying most deterministic analyses of their durability. This analysis views Italian government longevity as essentially indeterminate, or stochastic, and it applies the theory of “political reliability” to explain the probability that an Italian government will be in power at time t after it was formed. An exponential survival model R = e−kt, with constant government breakdown rate k = .021 per week, is developed, estimated, tested, and discussed. It is shown that Italian governments have a half-life (τ) of approximately 32.8 weeks, after which their political reliability drops below .50, and their mean duration is 47.7 weeks, so the probability that an Italian government will survive as long as the average is only 36.8%. Theoretical aspects of the model are also discussed, together with characteristic features of exponential political reliability, such as lifetime density, political mortality, and government downfall rate, as well as the systems reliability and crisis process characteristic of Italian governments.

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