Computational and Experimental Insights into the Role of Acidic Molecules on the Corrosion Behavior on 7A46 Aluminum Alloy

2021 ◽  
Vol 21 (4) ◽  
pp. 2221-2233
Author(s):  
Yaru Liu ◽  
Qinglin Pan ◽  
Xiangdong Wang ◽  
Ye Ji ◽  
Qicheng Liu ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Aluminum Alloy ◽  
Corrosion Behavior ◽  
First Principles ◽  
First Principles Calculations ◽  
Corrosive Media ◽  
Corrosion Depth ◽  
Corrosion Mechanisms ◽  
Nanoscale Level

The corrosion mechanisms for different corrosive media on the aged 7A46 aluminum alloy were systematically investigated at nanoscale level. The combination of empirical intergranular and exfoliation corrosion behavior was employed, and coupled with first-principles calculations. Results revealed that the dispersed distribution of matrix precipitates (MPs) leads to the enhancement of the corrosion resistance pre-ageing (PA) followed by double-ageing (PA-DA) alloy. The deepest corrosion depth of PA-DA alloy was in hydrochloric acid, and the calculation result demonstrates that the passivation effect in combination with the accumulation of corrosion products in nitric acid protect the PA-DA alloy from further corrosion.

An effective and efficient approach to p-type AlN by Be2:O codoping from first-principles calculations

2016 ◽  
Vol 30 (20) ◽  
pp. 1650257
Author(s):  
Meng Zhao ◽  
Wenjun Wang ◽  
Jun Wang ◽  
Junwei Yang ◽  
Weijie Hu ◽  
...  
Keyword(s):  
First Principles ◽  
Ionization Energy ◽  
Hole Concentration ◽  
Valence Band Maximum ◽  
First Principles Calculations ◽  
Mutual Compensation ◽  
Efficient Approach ◽  
P Type ◽  
Codoping Method

Various Be:O-codoped AlN crystals have been investigated via first-principles calculations to evaluate the role of the different combinations in effectively and efficiently inducing p-type carriers. It is found that the O atom is favored to bond with two Be atoms. The formed Be2:O complexes decrease the acceptor ionization energy to 0.11 eV, which is 0.16 eV lower than that of an isolated Be in AlN, implying that the hole concentration could probably be increased by 2–3 orders of magnitude. The electronic structure of Be2:O-codoped AlN shows that the lower ionization energy can be attributed to the interaction between Be and O. The Be–O complexes, despite failing to induce p-type carriers for the mutual compensation of Be and O, introduce new occupied states on the valence-band maximum (VBM) and hence the energy needed for the transition of electrons to the acceptor level is reduced. Thus, the Be2:O codoping method is expected to be an effective and efficient approach to realizing p-type AlN.

Role of Tartaric Acid on the Anodizing and Corrosion Behavior of AA 2024 T3 Aluminum Alloy

2009 ◽  
Vol 156 (4) ◽  
pp. C147 ◽  
Author(s):  
M. Curioni ◽  
P. Skeldon ◽  
E. Koroleva ◽  
G. E. Thompson ◽  
J. Ferguson
Keyword(s):  
Aluminum Alloy ◽  
Tartaric Acid ◽  
Corrosion Behavior ◽  
Aa 2024

The Role of Phase Stability in Ductile, Ordered B2 Intermetallics

2006 ◽  
Vol 980 ◽  
Author(s):  
James R. Morris ◽  
Yiying Ye ◽  
Maja Krcmar ◽  
Chong Long Fu
Keyword(s):  
Phase Stability ◽  
First Principles ◽  
Tensile Ductility ◽  
Stacking Faults ◽  
Low Energy ◽  
First Principles Calculations ◽  
Phase Competition ◽  
Transformation Pathway ◽  
Shape Memory Materials

AbstractWe discuss the underlying atomistic mechanism for experimentally observed large tensile ductility in various strongly ordered B2 intermetallic compounds. First-principles calculations demonstrate that all of the compounds exhibit little energy differences between the B2, B27 and B33 phases. These calculations relate observations of ductility in YAg, YCu and ZrCo to shape-memory materials including NiTi. One transformation pathway between the B2 and B33 phases establishes a connection between this phase competition, and stacking faults on the {011}B2 plane. The low energy of such a stacking fault will lead to splitting of the b=<100> dislocations into b/2 partials, observed in ZrCo, TiCo, and in the B19' phase of NiTi. Calculations demonstrate that this pathway is competitive with the traditional pathway for NiTi.

Electronic Structure and Hydrogen Desorption in NaAlH4

2004 ◽  
Vol 837 ◽  
Author(s):  
S. Li ◽  
P. Jena ◽  
C. M. Araujo ◽  
R. Ahuja
Keyword(s):  
Electronic Structure ◽  
First Principles ◽  
Density Functional ◽  
Metal Hydrides ◽  
Hydrogen Desorption ◽  
Light Metal ◽  
First Principles Calculations ◽  
Functional Theory ◽  
Design And Synthesis

ABSTRACTFirst principles calculations based on gradient corrected density functional theory are carried out to understand the electronic structure and mechanisms responsible for desorption of hydrogen from Ti doped and vacancy containing sodium-alanate (NaAlH4). The energy necessary to remove a hydrogen atom from Ti doped NaAlH4 is significantly smaller than that from pristine NaAlH4 irrespective of whether Ti substitutes the Na or the Al site. However, the presence of Na and Al vacancies is shown to play an even more important role: The removal of hydrogen associated with both Na and Al vacancies is found to be exothermic. It is suggested that this role of vacancies can be exploited in the design and synthesis of complex light metal hydrides suitable for hydrogen storage.

Theoretical search for high-performance thermoelectric donor–acceptor copolymers: the role of super-exchange couplings

2020 ◽  
Vol 8 (41) ◽  
pp. 21852-21861
Author(s):  
Xue Yong ◽  
Gang Wu ◽  
Wen Shi ◽  
Zicong Marvin Wong ◽  
Tianqi Deng ◽  
...  
Keyword(s):  
Effective Mass ◽  
Power Factor ◽  
First Principles ◽  
High Performance ◽  
First Principles Calculations ◽  
Thermoelectric Power Factor ◽  
Hole Effective Mass ◽  
Donor Acceptor ◽  
Weak Electron

First-principles calculations of a series of representing D–A copolymers demonstrated the strong Super-Exchange couplings induce not only small hole effective mass but also weak electron-phonon couplings, and eventually high thermoelectric power factor.

scholarly journals Low Temperature Sealing of Anodized Aluminum Alloy for Enhancing Corrosion Resistance

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4904
Author(s):  
Hyunbin Jo ◽  
Soomin Lee ◽  
Donghyun Kim ◽  
Junghoon Lee
Keyword(s):  
Corrosion Resistance ◽  
Aluminum Alloy ◽  
Current Density ◽  
Corrosion Current Density ◽  
Corrosion Current ◽  
Anodic Oxide ◽  
Nickel Acetate ◽  
Anodized Aluminum ◽  
Corrosive Media ◽  
Nickel Fluoride

Sealing as a post treatment of anodized aluminum is required to enhance the corrosion resistance by filling nanopores, which allow the penetration of corrosive media toward the base aluminum. We designed a mixed sealing solution with nickel acetate and ammonium fluoride by modifying traditional nickel fluoride cold sealing. The concentration of mixed sealing solution affected the reaction rate of sealing and corrosion current density of anodized aluminum alloy. The higher concentration of mixed sealing solution improved the sealing rate, which was represented by a decrease of corrosion current density of anodized aluminum alloy. However, a mixed sealing solution with 2/3 concentration of general nickel fluoride sealing solution operated at room temperature showed the lowest corrosion current density compared to traditional methods (e.g., nickel fluoride cold sealing (NFCS) and nickel acetate hot sealing) and other mixed sealing solutions. Moreover, the mixed sealing solution with 2/3 concentration of general NFCS had a lower risk for over sealing, which increases the corrosion current density by excessive dissolution of anodic oxide. Therefore, the mixed sealing solution with optimized conditions designed in this work possibly provides a new method for enhancing the corrosion resistance of anodized aluminum alloys.

scholarly journals The role of the VZn–NO–H complex in the p-type conductivity in ZnO

2015 ◽  
Vol 17 (7) ◽  
pp. 5485-5489 ◽  
Author(s):  
M. N. Amini ◽  
R. Saniz ◽  
D. Lamoen ◽  
B. Partoens
Keyword(s):  
First Principles ◽  
Formation Energy ◽  
First Principles Calculations ◽  
Deep Acceptor ◽  
Type Conductivity ◽  
Acceptor Complex ◽  
Hole Level ◽  
P Type

With the help of first-principles calculations, we investigate the VZn–NO–H acceptor complex in ZnO. We find that H plays an important role, because it lowers the formation energy of the complex with respect to VZn–NO, a complex known to exhibit p-type behavior. However, this additional H atom also occupies the hole level of VZn–NO making the VZn–NO–H complex a deep acceptor.

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