Solving the Structure of the Phases in the Al-Mg-Si Alloy System with the Help of Ab Initio Modelling

2002 ◽  
Vol 755 ◽  
Author(s):  
A. G. Froseth ◽  
S. J. Andersen ◽  
C. D. Marioara ◽  
P. M. Derlet ◽  
R. Hoier
Keyword(s):  
Electronic Structure ◽  
Ab Initio ◽  
Alloy System ◽  
Hardened Alloy ◽  
Β Phase ◽  
Dislocation Movement ◽  
Series Alloy ◽  
Microscopy Techniques ◽  
6Xxx Series ◽  
Insight Into

ABSTRACTThe Al-Mg-Si (6xxx-series) alloy system is a precipitation hardened alloy gaining much of its strength from precipitate phases acting as pinning centers for dislocation movement. Five years ago, Zandbergen, Andersen and coworkers identified the crystallography of the so-called β″ phase, one of the main hardening phases, using solely electron microscopy techniques [1]. Later, several other phases have been identified using high resolution microscopy. To solve the crystallography of these phases and to get an increased understanding of the electronic structure and bonding, ab initio modeling has proven to be a valuable tool. We present results from calculations on two recently discovered phases and show how ab initio modeling can give insight into the bonding trends and electronic structure of the phases in this alloy system.

STUDIES ON AGE HARDENING FOR IMPROVEMENT OF 6261 AND 6060 EXTRUDED ALUMINIUM ALLOYS

2010 ◽  
Vol 24 (15n16) ◽  
pp. 2255-2260
Author(s):  
KA KI (KATIE) AU ◽  
MICHAEL HODGSON ◽  
TIMOTIUS PASANG ◽  
YU LUNG CHIU
Keyword(s):  
Aluminium Alloys ◽  
Extrusion Process ◽  
Magnesium Silicide ◽  
Age Hardening ◽  
Precipitate Size ◽  
Β Phase ◽  
Heat Treated ◽  
Series Alloy ◽  
Main Components ◽  
6Xxx Series

The magnesium silicide precipitates in the 6XXX series alloy are the main components contributing to the heat treatable properties and T6 strength of the alloy, which is influenced by the size, morphology and distribution of this phase. During the extrusion process, the strength contributing phase, magnesium silicide is supposed to dissolve and form again in a controlled state during age hardening. Whereas the intermetallic AlFeSi phase has little if any influence on the strength, the β phase of this intermetallic is known to cause brittle fracture of this alloy, as opposed to the less detrimental, more equiaxed α phase formed during homogenisation. This study investigates the as-extruded 6060 and the more heavily alloyed 6261 aluminium alloys, as well as the subsequent heat treated forms to investigate the ageing conditions to optimise hardening and shorten age hardening times for higher cost effectiveness. The microstructure, texture and precipitate size and distributions were studied using optical microscopy, SEM, EBSD and DSC. SEM and EDAX results have indicated signs of evenly distributed α AlFeSi and β Magnesium Silicide precipitates. The phase responsible for hardening is believed to be the much smaller scaled β" magnesium silicide, requiring much higher resolution studies.

Quantum Mechanical Interpretation of the Ultra-Low Energy Methyl-Rotation Dynamics in Porous Metal-Organic Frameworks Probed by Low-Frequency Vibrational Spectroscopy and ab initio Simulations

2018 ◽  
Author(s):  
Qi Li ◽  
Adam J. Zaczek ◽  
Timothy M. Korter ◽  
J. Axel Zeitler ◽  
Michael T. Ruggiero
Keyword(s):  
Ab Initio ◽  
Metal Organic Frameworks ◽  
Low Frequency ◽  
Rotor Dynamics ◽  
Quantum Mechanical ◽  
Valuable Insight ◽  
Void Space ◽  
Ab Initio Simulations ◽  
Metal Organic ◽  
Insight Into

<div>Understanding the nature of the interatomic interactions present within the pores of metal-organic frameworks</div><div>is critical in order to design and utilize advanced materials</div><div>with desirable applications. In ZIF-8 and its cobalt analogue</div><div>ZIF-67, the imidazolate methyl-groups, which point directly</div><div>into the void space, have been shown to freely rotate - even</div><div>down to cryogenic temperatures. Using a combination of ex-</div><div>perimental terahertz time-domain spectroscopy, low-frequency</div><div>Raman spectroscopy, and state-of-the-art ab initio simulations,</div><div>the methyl-rotor dynamics in ZIF-8 and ZIF-67 are fully charac-</div><div>terized within the context of a quantum-mechanical hindered-</div><div>rotor model. The results lend insight into the fundamental</div><div>origins of the experimentally observed methyl-rotor dynamics,</div><div>and provide valuable insight into the nature of the weak inter-</div><div>actions present within this important class of materials.</div>

ALCOA ULTRALLOY X6020

Alloy Digest ◽  
1996 ◽  
Vol 45 (12) ◽  
Keyword(s):  
Corrosion Resistance ◽  
Surface Treatment ◽  
Tensile Properties ◽  
Lead Free ◽  
Aluminum Association ◽  
Wire Rod ◽  
Series Alloy ◽  
6Xxx Series

Abstract UltrAlloy is a lead-free, enhanced machining product with the inherent benefits of a 6xxx-series alloy. The alloy is produced as a cold-finished rod and bar with strength levels comparable to 6262. The alloy is registered with the Aluminum Association as X6020. This datasheet provides information on composition, microstructure, hardness, and tensile properties. It also includes information on corrosion resistance as well as forming, machining, joining, and surface treatment. Filing Code: AL-340. Producer or source: ALCOA Wire, Rod & Bar Division. Originally published September 1996, corrected December 1996.

scholarly journals Intergranular Corrosion and Microstructural Evolution in a Newly Designed Al-6Mg Alloy

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3314
Author(s):  
Kweon-Hoon Choi ◽  
Bong-Hwan Kim ◽  
Da-Bin Lee ◽  
Seung-Yoon Yang ◽  
Nam-Seok Kim ◽  
...  
Keyword(s):  
Intergranular Corrosion ◽  
Alloy System ◽  
Critical Factors ◽  
Phase Precipitation ◽  
Grain Sizes ◽  
Β Phase ◽  
Mass Losses ◽  
Cold Rolling Reduction ◽  
Cold Rolled ◽  
Sensitization Time

In this work, the microstructure and corrosion behavior of a novel Al-6Mg alloy were investigated. The alloy was prepared by casting from pure Al and Mg+Al2Ca master alloy. The ingots were homogenized at 420 °C for 8 h, hot-extruded and cold-rolled with 20% reduction (CR20 alloy) and 50% reduction (CR50 alloy). The CR50 alloy exhibited a higher value of intergranular misorientation due to a higher cold rolling reduction ratio. The average grain sizes were 19 ± 7 μm and 17 ± 9 μm for the CR20 and CR50 alloys, respectively. An intergranular corrosion (IGC) behavior was investigated after sensitization by a nitric acid mass-loss test (ASTM G67). The mass losses of both the CR20 and CR50 alloys were similar at early periods of sensitization, however, the CR20 alloy became more susceptible to IGC as the sensitization time increased. Grain size and β phase precipitation were two critical factors influencing the IGC behavior of this alloy system.

scholarly journals Indirect bandgap, optoelectronic properties, and photoelectrochemical characteristics of high-purity Ta3N5 photoelectrodes

2021 ◽  
Vol 9 (36) ◽  
pp. 20653-20663
Author(s):  
Johanna Eichhorn ◽  
Simon P. Lechner ◽  
Chang-Ming Jiang ◽  
Giulia Folchi Heunecke ◽  
Frans Munnik ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Electronic Properties ◽  
High Purity ◽  
Optoelectronic Properties ◽  
Precise Control ◽  
Insight Into

The (opto)electronic properties of Ta3N5 photoelectrodes are often dominated by defects, but precise control of these defects provides new insight into the electronic structure, photocarrier transport, and photoelectrochemical function.

Electronic structure and optical properties of CuWO4: An ab initio study

2012 ◽  
Vol 63 ◽  
pp. 163-167 ◽  
Author(s):  
M.V. Lalić ◽  
Z.S. Popović ◽  
F.R. Vukajlović
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
Ab Initio ◽  
Ab Initio Study
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