The Portevin-Le Chatelier effect in corrosion behavior of the Mg-Zn-Sr alloy

CORROSION ◽  
10.5006/3788 ◽  
2021 ◽  
Author(s):  
Xiaole Gong ◽  
jihua chen ◽  
Hongge Yan ◽  
Weijun Xia ◽  
Bin Su ◽  
...  
Keyword(s):  
Dislocation Density ◽  
Corrosion Rate ◽  
Stress Corrosion Cracking ◽  
Tensile Testing ◽  
Density Region ◽  
Slip Bands ◽  
Low Dislocation Density ◽  
Deformation Ability ◽  
Chatelier Effect ◽  
The Impact

The as-solutionized Mg-4Zn alloys, one candidate material for biological implantation, are featured with the Portevin-Le Chatelier effect during the tensile testing with strain rate of 6.67×10-7 s-1, which leads to the higher corrosion rate and the acceleration of stress corrosion cracking. With the increase of the strain, new slip bands are generated and the proliferation of dislocations is very rapid in slip bands. The microgalvanic corrosion occurs between the slip bands (anode) and the low-dislocation-density region (cathode). The 0.1 wt. % Sr addition can reduce the impact of the Portevin-Le Chatelier effect on as-solutionized Mg-4Zn alloy, resulting from the inhibition of twin, the better grain coordination deformation ability and the lower density of geometrically necessary dislocations.

Reduction of Dislocations in the Bulk Growth of SiC Crystals

2006 ◽  
Vol 527-529 ◽  
pp. 3-8 ◽  
Author(s):  
Daisuke Nakamura
Keyword(s):  
Dislocation Density ◽  
Growth Process ◽  
Large Diameter ◽  
Device Performance ◽  
Etch Pit Density ◽  
Bulk Growth ◽  
Etch Pit ◽  
Low Dislocation Density ◽  
The Impact

Recent reports on the impact of elementary dislocations on device performance and reliability suggest not only micropipe defects but also dislocations should be reduced or eliminated perfectly. This paper presents bulk growth process for reduction of the dislocations, and quality of the crystals grown by the process. Etch pit density of the best crystals grown by the process was lower by three orders of magnitude than that of conventional crystals. Moreover, large diameter crystals (>2”) with low dislocation density were successfully grown by the process.

Low dislocation density AlN on sapphire prepared by double sputtering and annealing

2020 ◽  
Vol 13 (9) ◽  
pp. 095501
Author(s):  
Ding Wang ◽  
Kenjiro Uesugi ◽  
Shiyu Xiao ◽  
Kenji Norimatsu ◽  
Hideto Miyake
Keyword(s):  
Dislocation Density ◽  
Low Dislocation Density

Growth Of Low-Dislocation-Density InP Single Crystals By The VCZ Method

1989 ◽  
Author(s):  
M. Tatsumi ◽  
T. Kawase ◽  
T. Araki ◽  
N. Yamabayashi ◽  
T. Iwasaki ◽  
...  
Keyword(s):  
Dislocation Density ◽  
Single Crystals ◽  
Low Dislocation Density

Test and Study on Impact of Corrosion on Bond Force between Steel and Concrete

2010 ◽  
Vol 36 ◽  
pp. 176-181
Author(s):  
Xian Feng He ◽  
Shou Gang Zhao ◽  
Yuan Bao Leng
Keyword(s):  
Reinforced Concrete ◽  
Corrosion Rate ◽  
Concrete Structure ◽  
Steel Corrosion ◽  
Reinforced Concrete Structure ◽  
Bond Force ◽  
Steel Bars ◽  
Protection Layer ◽  
Corrosion Of Steel ◽  
The Impact

The corrosion of steel will have a bad impact on the safety of reinforced concrete structure. In severe cases, it may even be disastrous. In order to understand the impact of steel corrosion on the structure, tests are carried out to study corrosion and expansion rules of steel bars as well as the impact rules of corrosion on bond force between steel and concrete. The results show that wet and salty environment will result in steel corrosion; relatively minor corrosion will not cause expansion cracks of protection layers; when steel rust to a certain extent, it will cause cracks along the protection layer; when there exists minor corrosion in steel and the protection layer does not have expansion cracks, the bond force is still large and rapidly decreases as the corrosion rate increases.

Trenched epitaxial lateral overgrowth of fast coalesced a-plane GaN with low dislocation density

2006 ◽  
Vol 89 (25) ◽  
pp. 251109 ◽  
Author(s):  
Te-Chung Wang ◽  
Tien-Chang Lu ◽  
Tsung-Shine Ko ◽  
Hao-Chung Kuo ◽  
Min Yu ◽  
...  
Keyword(s):  
Dislocation Density ◽  
Epitaxial Lateral Overgrowth ◽  
Lateral Overgrowth ◽  
Low Dislocation Density

Discussion of Oxygen Threshold Level for Corrosion Management in Seawater Injection Systems

2021 ◽  
Author(s):  
Jean Vicente Ferrari
Keyword(s):  
Corrosion Rate ◽  
Oxygen Reduction ◽  
Water Injection ◽  
Steel Corrosion ◽  
Threshold Level ◽  
International Standards ◽  
Limiting Current ◽  
Order Of Magnitude ◽  
The Impact ◽  
Oxygen Concentrations

Abstract Generally, in water injection systems, oxygen levels starting from around eight ppm are deoxygenated to below 50 ppm, following international standards' guidelines. This work aims to discuss the impact of such a magnitude value of oxygen contamination on steel corrosion in seawater injection systems by analysing theoretical polarisation curves and results from published works with different approaches. Corrosion models consider mass-transfer controlled diffusion of oxygen to predict the maximum steel corrosion rate, which depends on the oxygen limiting current, which in turn is strongly influenced by flow velocity. The effect of free chlorine on corrosion in seawater injection systems has also been considered and included in an oxygen equivalent parameter. In such systems, where oxygen reduction is the key cathodic reaction, the corrosion process may be under cathodic activation control, independent of flow at higher velocities or when erosion-corrosion begins. In this work, theoretical polarisation curves were constructed by using published oxygen and chlorine cathodic limiting currents (iLc) on carbon steel and a noble metal electrode, respectively. Aerated (200 ppb and 9000 ppb of oxygen) and deaerated conditions (50 ppb of oxygen) and the presence of 300 ppb of chlorine were applied to the assumed exchange current densities (io). Neutral (pH 7) and acid (pH 4) conditions (considering the presence of CO2) were also assumed to be at room temperature and pressure. Since the corrosion rate in lower oxygen concentrations (ppb order of magnitude) may result in corrosion rates of the same order of magnitude than in higher oxygen concentrations (ppm order of magnitude) when comparing and analysing results from experimental, semi-empirical or mechanistic approaches, it is necessary to weigh up the effects of both steel surface (bare or scaled/corrosion products) and flow. At oxygen concentrations below 200 ppb and under acid conditions, the contribution of H+ reduction on corrosion rate starts to be higher than oxygen reduction, mainly in the absence of chlorine.

Heteroepitaxy and Characterization of Low-Dislocation-Density GaN on Periodically Grooved Substrates

2000 ◽  
Vol 639 ◽  
Author(s):  
T. Detchprohm ◽  
M. Yano ◽  
R. Nakamura ◽  
S. Sano ◽  
S. Mochiduki ◽  
...  
Keyword(s):  
Dislocation Density ◽  
New Method ◽  
Growth Technique ◽  
New Approach ◽  
Density Area ◽  
Low Dislocation Density ◽  
Dislocation Densities ◽  
Movpe Growth

ABSTRACTWe have developed a new method to prepare low-dislocation-density GaN by using periodically grooved substrates in a conventional MOVPE growth technique. This new approach was demonstrated for GaN grown on periodically grooved α-Al2O3(0001), 6H-SiC(0001)Si and Si(111) substrates. Dislocation densities were 2×107 cm−2 in low-dislocation-density area.

scholarly journals Oxide Thin Film Heterostructures on Large Area, with Flexible Doping, Low Dislocation Density, and Abrupt Interfaces: Grown by Pulsed Laser Deposition

2010 ◽  
Vol 2010 ◽  
pp. 1-27 ◽  
Author(s):  
Michael Lorenz ◽  
Holger Hochmuth ◽  
Christoph Grüner ◽  
Helena Hilmer ◽  
Alexander Lajn ◽  
...  
Keyword(s):  
Thin Film ◽  
Dislocation Density ◽  
Pulsed Laser Deposition ◽  
Pulsed Laser ◽  
Chemical Vapor ◽  
Laser Deposition ◽  
Oxide Thin Film ◽  
Organic Chemical ◽  
Large Area ◽  
Low Dislocation Density

Advanced Pulsed Laser Deposition (PLD) processes allow the growth of oxide thin film heterostructures on large area substrates up to 4-inch diameter, with flexible and controlled doping, low dislocation density, and abrupt interfaces. These PLD processes are discussed and their capabilities demonstrated using selected results of structural, electrical, and optical characterization of superconducting (YBa2Cu3O7−δ), semiconducting (ZnO-based), and ferroelectric (BaTiO3-based) and dielectric (wide-gap oxide) thin films and multilayers. Regarding the homogeneity on large area of structure and electrical properties, flexibility of doping, and state-of-the-art electronic and optical performance, the comparably simple PLD processes are now advantageous or at least fully competitive to Metal Organic Chemical Vapor Deposition or Molecular Beam Epitaxy. In particular, the high flexibility connected with high film quality makes PLD a more and more widespread growth technique in oxide research.

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