Electrochemical behavior of 6xxx series aluminium alloys in electrolytes containing chloride ions

2020 ◽  
Vol 1679 ◽  
pp. 042095
Author(s):  
I V Dubova ◽  
T R Gilmanshina ◽  
N V Vasyunina ◽  
G S Sanacheva ◽  
O V Chupriy
2016 ◽  
Vol 190 ◽  
pp. 92-103 ◽  
Author(s):  
S.K. Kairy ◽  
P.A. Rometsch ◽  
K. Diao ◽  
J.F. Nie ◽  
C.H.J. Davies ◽  
...  

2010 ◽  
Vol 24 (15n16) ◽  
pp. 2255-2260
Author(s):  
KA KI (KATIE) AU ◽  
MICHAEL HODGSON ◽  
TIMOTIUS PASANG ◽  
YU LUNG CHIU

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.


2006 ◽  
Vol 519-521 ◽  
pp. 543-548 ◽  
Author(s):  
A.I. Morley ◽  
M.W. Zandbergen ◽  
Alfred Cerezo ◽  
George D.W. Smith

Hardness measurements and 3-dimensional atom probe analysis have been used to characterise the precipitation behaviour in two 6xxx series aluminium alloys, one Cu-free alloy (Al-0.78at%Mg- 0.68at%Si) and one Cu-containing alloy (Al-0.78at%Mg-0.68at%Si-0.30at%Cu). The heat treatments consisted of either natural ageing or pre-ageing at 353K followed by a paint-bake treatment at 453K. Natural ageing was seen to increase the hardness, and hence reduce formability compared to pre-ageing. In addition, the strengthening effect of artificial ageing was less after natural ageing than after pre-ageing. In the Cu-free alloy, needle-like β″ was observed to form only after a pre-ageing treatment during the first 60 minutes of a paint-bake treatment. In the Cucontaining alloy, needle-like β″ formed during paint bake in both the naturally-aged and pre-aged material, although it is formed more rapidly after pre-ageing. This was accompanied by an increase in strength over the Cu-free alloy and indicates that Cu reduces the deleterious effect of natural ageing.


1975 ◽  
Vol 53 (3) ◽  
pp. 389-406 ◽  
Author(s):  
Remigio Germano Barradas ◽  
Keith Belinko ◽  
John Ambrose

The electrochemical properties of lead electrodes in aqueous chloride solutions were experimentally investigated over a range of 0.1 to 6.0 M HCl with the aim of extending previous work carried out only at 1.0 M HCl concentration. Experimental results using the rotating disc electrode technique, cyclic voltammetry, galvanostatic and potentiostatic charging conditions were employed in conjunction with spectroscopic studies of the electrolyte and X-ray powder diffraction analyses of electrode surface products. Experiments were also carried out in simulated sea water (3% NaCl) at different pH and compared with results obtained using HCl at the same molar concentration. At all chloride concentrations the overall reaction led to the formation of PbCl2 on the electrode surface, with the exception that in NaCl solutions where pH ≥ 6.5, Pb(OH)Cl was found to be one of the products. For concentrations of less than 0.4 M HCl, our results indicated that the diffusion of chloride ions to the electrode surface was the limiting factor in the formation of a passivating PbCl2 layer. At concentrations of about 0.7 M HCl, the electrochemical behavior showed a pattern of results which were interpreted in terms of a "passivation–dissolution" competitive mechanism consistent with the solubility minimum of PbCl2 in aqueous chloride solutions.


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