scholarly journals Role of Small Addition of Sc and Zr in Clustering and Precipitation Phenomena Induced in AA7075

Metals ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 8
Author(s):  
Martin Vlach ◽  
Veronika Kodetova ◽  
Jakub Cizek ◽  
Michal Leibner ◽  
Tomáš Kekule ◽  
...  
Keyword(s):  
Positive Influence ◽  
Corrosion Properties ◽  
Mechanical And Electrical Properties ◽  
Zr Addition ◽  
Heat Treated ◽  
Precipitation Phenomena ◽  
T Phase ◽  
Mgzn2 Phase

A detailed characterization of phase transformations in the heat-treated commercial 7075 aluminum alloys without/with low Sc–Zr addition was carried out. Mechanical and electrical properties, thermal and corrosion behavior were compared to the microstructure development. The eutectic phase consists of four parts: MgZn2 phase, Al2CuMg phase (S-phase), Al2Zn3Mg3 phase (T-phase), and primary λ-Al(Mn,Fe,Si) phase. Strengthening during non-isothermal (isochronal) annealing is caused by a combination of formation of the GP zones, η’-phase, T-phase and co-presence of the primary and secondary Al3(Sc,Zr)-phase particles. Positive influence on corrosion properties is owing to the addition of Sc–Zr. Positron annihilation showed an evolution of solute Zn,Mg-(co-)clusters into (precursors of) the GP zones in the course of natural ageing. The concentration of the (co-)clusters is slightly negatively affected by the low Sc–Zr addition. A combination of both precipitation sequences of the Al–Zn–Mg–Cu-based system was observed. The apparent activation energy values for dissolution/formation of the clusters/GP zones and for formation of the metastable η’-phase, stable T-phase and stable η-phase were calculated.

scholarly journals Characterization of polyparaphenylene (PPP)-based carbons

1996 ◽  
Vol 11 (12) ◽  
pp. 3099-3109 ◽  
Author(s):  
M. J. Matthews ◽  
M. S. Dresselhaus ◽  
M. Endo ◽  
Y. Sasabe ◽  
T. Takahashi ◽  
...  
Keyword(s):  
Crystallite Size ◽  
Electrical Characteristics ◽  
X Ray Diffraction ◽  
X Ray ◽  
Secondary Battery ◽  
Heat Treated ◽  
Raman Modes ◽  
Integrated Intensities

Polyparaphenylene (PPP)-based carbons heat-treated at temperatures (THT) from 600 °C up to 3000 °C have been characterized both structurally and in terms of their physical properties. Special attention is given to PPP heat-treated at 700 °C (denoted by PPP-700), since samples heat-treated to this temperature were observed to have exceptionally high lithium affinities when electrochemically doped with Li. At low THT below 700 °C, it is found that the local structure of PPP-based samples can be characterized mostly in terms of a disordered polymer. As a result of heat treatment to high temperature, PPP-based carbon shows graphitization behavior with regard to x-ray diffraction d002 (graphite c-axis d-spacing) development and to the increase of the Raman IG/ID intensity ratio (where IG and ID are the integrated intensities of the 1580 cm−1 and 1360 cm−1 Raman modes, respectively), as is found in so-called graphitizing carbons. However, development of the c-axis crystallite size (Lc) is restricted to very small values, in the range of so-called nongraphitizing carbons, while the a-axis crystallite size (La) attains values up to roughly 120 Å for heat treatments near 3000 °C. These structural properties of PPP-based carbons are consistent with the observed electrical characteristics and their dependence on THT. Low temperature magnetic susceptibility measurements were analyzed, along with Raman spectra, allowing for the characterization of disorder in terms of localized spin states for several heat-treated PPP samples. By interpreting the results of these various characterization techniques, we are able to present an insightful perspective on the nature of PPP-based carbons and the role of PPP-700 as an effective lithium host material for secondary battery applications.

Gene expression and activity analysis of the first thermophilic U32 peptidase

2012 ◽  
Vol 7 (4) ◽  
pp. 587-595
Author(s):  
Andrius Jasilionis ◽  
Algirdas Kaupinis ◽  
Marija Ger ◽  
Mindaugas Valius ◽  
Donaldas Chitavichius ◽  
...  
Keyword(s):  
Gene Expression ◽  
Recombinant Protein ◽  
Thermophilic Bacteria ◽  
Activity Analysis ◽  
First Report ◽  
Geobacillus Thermoleovorans ◽  
Heat Treated ◽  
Expression And Activity

AbstractPeptidase family U32 is one of the few whose catalytic type and structure has not yet been described. It is generally accepted that U32 peptidases represent putative collagenases and contribute to the pathogenicity of some bacteria. Meanwhile, U32 peptidases are also found in nonpathogenic bacteria including thermophiles and hyperthermophiles. Here we report cloning of the U32.002 peptidase gene from thermophilic Geobacillus thermoleovorans DSM 15325 and demonstrate expression and characterization of the recombinant protein. It has been determined that U32.002 peptidase is constitutively expressed in the cells of thermophilic G. thermoleovorans DSM 15325. The recombinant oligomeric enzyme showed its activity only against heat-treated collagen. It was unable to degrade albumin, casein, elastin, gelatine and keratin. In contrast to this, the monomeric recombinant protein showed no activity at all. This paper is the first report about the thermophilic U32 peptidase. As the thermophilic bacteria are non-pathogenic, the role of constitutively expressed extracellular collagenolytic U32 peptidase in these bacteria is unclear.

Characterization of carbides in M50NiL

1991 ◽  
Vol 49 ◽  
pp. 606-607
Author(s):  
L. S. Lin ◽  
K. P. Gumz ◽  
A. V. Karg ◽  
C. C. Law
Keyword(s):  
Temperature Effects ◽  
Base Composition ◽  
Lattice Parameter ◽  
Control Surface ◽  
Carbide Formation ◽  
Particle Sizes ◽  
Low Carbon ◽  
Fee Structure ◽  
Heat Treated

Carbon and temperature effects on carbide formation in the carburized zone of M50NiL are of great importance because they can be used to control surface properties of bearings. A series of homogeneous alloys (with M50NiL as base composition) containing various levels of carbon in the range of 0.15% to 1.5% (in wt.%) and heat treated at temperatures between 650°C to 1100°C were selected for characterizations. Eleven samples were chosen for carbide characterization and chemical analysis and their identifications are listed in Table 1.Five different carbides consisting of M6C, M2C, M7C3 and M23C6 were found in all eleven samples examined as shown in Table 1. M6C carbides (with least carbon) were found to be the major carbide in low carbon alloys (<0.3% C) and their amounts decreased as the carbon content increased. In sample C (0.3% C), most particles (95%) encountered were M6C carbide with a particle sizes range between 0.05 to 0.25 um. The M6C carbide are enriched in both Mo and Fe and have a fee structure with lattice parameter a=1.105 nm (Figure 1).

Digital x-ray mapping of nanometer-size supported bimetallic catalysts

1988 ◽  
Vol 46 ◽  
pp. 530-531
Author(s):  
L. T. Germinario
Keyword(s):  
Background Radiation ◽  
Metal Cluster ◽  
Single Element ◽  
Beam Diameter ◽  
X Rays ◽  
X Ray ◽  
Major Interest ◽  
Induced Changes

Understanding the role of metal cluster composition in determining catalytic selectivity and activity is of major interest in heterogeneous catalysis. The electron microscope is well established as a powerful tool for ultrastructural and compositional characterization of support and catalyst. Because the spatial resolution of x-ray microanalysis is defined by the smallest beam diameter into which the required number of electrons can be focused, the dedicated STEM with FEG is the instrument of choice. The main sources of errors in energy dispersive x-ray analysis (EDS) are: (1) beam-induced changes in specimen composition, (2) specimen drift, (3) instrumental factors which produce background radiation, and (4) basic statistical limitations which result in the detection of a finite number of x-ray photons. Digital beam techniques have been described for supported single-element metal clusters with spatial resolutions of about 10 nm. However, the detection of spurious characteristic x-rays away from catalyst particles produced images requiring several image processing steps.

Carbide precipitation and chromium depletion on coherent twin boundaries in deformed 304 stainless steels

1992 ◽  
Vol 50 (2) ◽  
pp. 1216-1217
Author(s):  
A.H. Advani ◽  
L.E. Murr ◽  
D.J. Matlock ◽  
W.W. Fisher ◽  
P.M. Tarin ◽  
...  
Keyword(s):  
Grain Boundaries ◽  
Stainless Steels ◽  
Interfacial Free Energy ◽  
Carbide Precipitation ◽  
Twin Boundaries ◽  
Invariant Structure ◽  
Heat Treated ◽  
Constant Structure ◽  
Cr Depletion

Coherent annealing-twin boundaries are constant structure and energy interfaces with an average interfacial free energy of ∼19mJ/m2 versus ∼210 and ∼835mJ/m2 for incoherent twins and “regular” grain boundaries respectively in 304 stainless steels (SS). Due to their low energy, coherent twins form carbides about a factor of 100 slower than grain boundaries, and limited work has also shown differences in Cr-depletion (sensitization) between twin versus grain boundaries. Plastic deformation, may, however, alter the kinetics and thermodynamics of twin-sensitization which is not well understood. The objective of this work was to understand the mechanisms of carbide precipitation and Cr-depletion on coherent twin boundaries in deformed SS. The research is directed toward using this invariant structure and energy interface to understand and model the role of interfacial characteristics on deformation-induced sensitization in SS. Carbides and Cr-depletion were examined on a 20%-strain, 0.051%C-304SS, heat treated to 625°C-4.5h, as described elsewhere.

Modulated structures in (Bi,Pb)-Sr-Ca-Cu-O films

1990 ◽  
Vol 48 (4) ◽  
pp. 62-63
Author(s):  
Shozo Ikeda ◽  
Hirotoshi Hayakawa ◽  
Daniel R. Dietderich
Keyword(s):  
Rf Magnetron Sputtering ◽  
Potential Method ◽  
High Tc ◽  
Bscco System ◽  
Heat Treated ◽  
Modulated Structures ◽  
High Tc Phase ◽  
Deposited Films ◽  
Sputtering System

Pb addition makes easier to form the high Tc phase in the BSCCO system. However, Pb easily vaporized at high temperature. A controlled Pb potential method has been applied to grow the high Tc phase in films. Initially, films are deposited on cleaved MgO substrates using an rf magnetron sputtering system. These amorphous as-deposited films are heat treated in a sealed gold capsule along with a large pellet of Pb-added BSCCO. Details of the process and characterization of the films have been reported elsewhere (1). Films trated for 0.5h at 850° C contain mainly the low Tc phase with a small amount of the high Tc phase. Hawever, films treated for 3h at 850°C consist mainly of the high Tc phase. This film is superconductive with a Tc(zero) of 106K. The Pb/Bi ratio of the films, analysed by SEM- EDS, are 0.12 and 0.18 for heat tratment times of 0.5 and 3h, respectively. The present study investigates the modulated structures of these films using HREM.

Analisis Pengembalian Kredit Terhadap Profitabilitas Pada PT Bank Sumut Cabang Gunungsitoli

Owner ◽  
2019 ◽  
Vol 3 (2) ◽  
pp. 160
Author(s):  
Victorinus Laoli
Keyword(s):  
Data Collection ◽  
Positive Influence ◽  
Business Continuity ◽  
Working Capital ◽  
The People ◽  
Data Collection Technique

One manifestation of the important role of banking in a region, as implemented by PT Bank Sumut, Gunungsitoli Branch, is to distribute loans for investment, consumption and working capital for the people in the area. The purpose of providing credit for banks is the return of credit that earns interest and can increase income to finance activities and business continuity. From the results of research conducted with this data collection technique, it shows that PT Bank Sumut has a number of loans from 2009 to 2014 which each year rises. From this study, it is also known that the rate of credit repayment has a positive influence on the level of profitability.

Consideraciones en torno a la reducción solipsista

1970 ◽  
Vol 11 ◽  
Author(s):  
Natalia Carolina Petrillo

ResumenEn el presente trabajo se intentará mostrar que la fenomenología no conduce a una postura solipsista. Para ello, se caracterizará en qué consiste el solipsismo. Luego, se intentará refutar a lo que se ha de llamar “solipsismo metafísico” y “solipsismo gnoseológico”, con el objetivo principal de poner de manifiesto el fundamento de motivación para la salida de la ficción solipsista.Palabras claves:Phenomenology – solipsim – empatía - HusserlAbstractWith the aim of showing that phenomenology does not lead in solipsism, I will first attempt a characterization of it. Then, I will attempt a refutation of the so-called “metaphysical” and “epistemological” solipsisms. Finally, the nature and role of Husserl´s solipsistic fiction is examined, and the grounds that motivate the overcoming of this standpoint are disclosed.key wordsFenomenología – solipsismo - empathy – Husserl

Sign in / Sign up

Export Citation Format

Share Document