Volume 5 Paper 11
Cu redeposition and surface enrichment during the dissolution of Al-Cu alloy in 0.1 M HCl
A.A. El Warraky, A.M. El-Aziz and Kh.A. Soliman
Keywords: Aluminium, Al-Cu Alloy, Copper enrichment, Copper release
Because you are not logged-in to the journal, it is now our policy to display a 'text-only' version of the paper. This version is obtained by extracting the text from the PDF or HTML file, and it is not guaranteed that the text will be a true image of the text of the paper. The text-only version is intended to act as a reference for search engines when they index the site, and it is not designed to be read by humans!
If you wish to view the human-readable version of the paper, then please Register (if you have not already done so) and Login. Registration is completely free.
Volume 5 Paper 11
Cu redeposition and surface enrichment during the dissolution of Al-Cu
alloy in 0.1 M HCl
A. A. El Warraky , A. M. El-Aziz and Kh. A. Soliman
Department of Electrochemistry and Corrosion, National Research Centre, Dokki, Cairo, Egypt.
The enrichment of Cu on the surface of Al-3.84%Cu alloy during the dissolution in 0.1 M HCl
has been examined using open circuit potential (OCP) accompanied by scanning electron microscopy
(SEM), Auger electron spectroscopy (AES) and x-ray photoelectron spectroscopy (XPS). Results
obtained during this study show that there are two types of Cu enrichment, one of them is in the form of
Cu clusters, which is formed due to the outer diffusion or segregation of Cu to the alloy surface. The
second type is more uniform deposition as a result of copper redeposition from solution, this data is
confirmed by the AES survey point analysis which show that the detection of Cu peak beside the
disappearance of Al peak occurred at the whole surface. It is also indicated that the Cu released from the
alloy surface is due to two different sources. The first occurred due to the severe galvanic attack, around
the breifery of the clusters. This attack can be extended under the cluster and released. The other was
attributed to the uniform redeposition of Cu on pure Al, where the disproportionation reaction of Cu
ions takes place on the surface, which can produce Cu
ions to the solution The higher resolution
multiplex of Cu using XPS analysis shows that the appearance of three peaks corresponding to Cu
(metallic copper), CuCl, CuCl 2 and devoid of any Al species. Accordingly the redeposit Cu on pure Al
can behaves as Cu metal and dissolves also as dichlorocoprate (CuCl-2) soluble complex beside CuCl2
Keywords Aluminum, Al-Cu alloy, Copper enrichment, Copper release
Corresponding author. E-mail address: firstname.lastname@example.org
This paper is published in the Journal of Corrosion Science and Engineering, published online at http://www.jcse.org/.
© UMIST 2004
Aluminium and its alloys have attracted many authors due to its widespread industrial
applications. Addition of copper as an alloying element in various aluminum alloys increases its
strength and also plays an important role in their corrosion behaviour.
Different treatment of the Al-Cu alloys such as chemical and electrochemical pretreatment [1-4],
electrochemical and other properties in different media: salts, alkalis and acids [5-12], causes
enrichment of the concentration of copper on the surface. The deleterious effect of the enrichment of
copper on the Al alloys surface is appeared as a result of galvanic couples set up between copper-rich
intermetallic particles θ (Al 2Cu) and the adjacent copper –depleted matrix which induce localized
corrosion [13-15]. Dealloying is an important feature of intermetallic compound, copper released and
redistributed. Corrosion and aqueous surface finishing of Al-Cu alloys cause dissolution, redistribution
and enrichment of Cu on the treated surface. .
Two different mechanism for copper surface enrichment have been proposed [17,18] as a result
of the dissolution of the alloy matrix. The two mechanism did not consider Cu release from Cu-rich
intermetallic compound particle dissolution as a main source of Cu surface enrichment. These
mechanisms are differ in that one of them depends on classic dealloying ,
where Cu is simply left
behind to accumulate on the surface. The second mechanism depends on homogeneous dissolution,
where copper released from the matrix phase to the solution either by surface curvature or cluster
formation. Buchheit et al  support both the classic dealloying and homogeneous dissolution
mechanism while the intermetallic compound dissolution appears to have its main effect on Cu release
and redistribution at short time and length scales.
Recently the exact mechanism of copper enrichment was said to occur either by a dissolution
and redeposition process or by some solid state enrichment followed by a nonfaradic transport process.
The third mechanism of the selective dissolution of aluminum leading to the formation of copper
particle [19-21] is however, a matter of some controversy.
The aim of the present work was to study the mechanism of enrichment of Cu on Al-3.84% Cu
alloy surface as well as the Cu release from the surface to the solution in 0.1M HCl.
Experiments were conducted on pure Al (99.99%) and Al- Cu alloys as used previously .
The surfaces of samples were abraded with emery paper of increasing fineness up to 1200 grit. Prior to
the experiment, the samples were washed with double distilled water, degreased with acetone and then
washed with double distilled water. The potentials were measured relative to a saturated calomel
Some of measurements were carried out when pure Al is immersed in 0.1 M HCl containing 0,
0.4, 1, 5, 20, 50, 100 and 200 ppm CuCl 2. Other measurements were conducted where a Al-Cu alloy is
immersed in 0.1 M HCl for different time of immersion
and a new sample of pure Al was immersed in the same solution which contains dissolved product of
the replaced Al-Cu alloy sample, where the change in potential is followed against time.
Measurements were also carried out when two samples, one of them is Al pure and the second is Al3.84 % Cu alloy, are immersed in 0.1 M HCl separately and the potential of each of them is followed
against time using two saturated calomel electrode. At the end of this experiment, the samples were
cleaned using ultra sonic vibration for 30 min. and were investigated using a scanning electron
microscopy (SEM) (JEOL, JSM T-20 Japan, accelerating voltage 19 KV), Auger electron spectroscopy
(AES) and x-ray photoelectron spectroscopy (XPS). The spectrometer for AES and XPS surface
analysis was a type 550 ESCA/ SAM (Physical Electronics, USA). The vacuum in the analytical
chamber was better than 10 -9. The adjustment of the XPS spectrometer, procedure for measurement and
analysis conductions have been described elsewhere . All experiments were carried out at room
temperature of 25 oC.
3.1 Potential – Time behaviour
The variation of the open circuit potential of Al pure metal, Al – Cu alloys and Cu pure metal
with time in 0.1 M HCl are shown in Fig. (1). In all curves, the potential shifted to more negative values
after the first instant of immersion. This behaviour is due to the dissolution of the pre immersion airformed oxide film carried out by the metal surface , which is not able to impart passivity.
From these curves the following consideration can be predicted.
(a) In case of Cu metal and Al-Cu alloys, the steady state potential of Cu electrode is attained after about
2 min. of immersion.
(b) The Al electrode acquires its final steady state potential after 180-200 min. of immersion, where the
potential is shifted to more negative value due to dissolution of the pre immersion oxide, which
extended up to 20-30 min. After that the potential changes its direction more slowly to exhibit nearly the
steady state potential, which acquires the same starting potential (-760 mV). This indicates that the
steady state potential is achieved by the formation of Al oxide .
(c) The presence of Cu with Al in all Al-Cu alloys (3.84 to 11 %) moves the potentials towards less
negative values (nearly 125 mV) with respect to pure Al. The steady state potential occurred at the first
instant of immersion as represented in case of Cu metal. This behaviour is attributed to the enrichment
of Cu on the alloy surface, as will be discussed briefly latter.
In Fig. (2) curves are drawn representing the variation of the potential of pure Al with time in
solution of 0.1 M HCl with increasing CuCl 2 additions varying between 0.4 and 200 ppm. These curves
show that as increasing the concentration of CuCl 2 the negative shift in potential is decreased after few
minutes of immersion (30 min.) and is nearly eliminated at 200 ppm CuCl 2 addition. This behaviour can
be regarded as a result of the competition between the dissolution of the pre immersion Al oxide and the
deposition of Cu metal from the solution.
On the other hand, the steady state potential depends on the concentration of CuCl
where a faster rate is obtained at 200 ppm of addition. At the steady state potential a slight oscillation in
the potential appeared and the recorded steady state values are nearly the same as that of Al-Cu alloys of
Fig. (1). These oscillations were due to the change in homogeneity of the surface, which its produced as
a result of the continuous deposition of Cu at the solid solution interface. Accordingly, the colour of
metallic copper was detected by naked eye.
The curves of Fig. (3) were obtained as a result of immersion of the Al-3.84% Cu alloy in 0.1 M
HCl for different time intervals of 2, 4 and 8 hr. After each time of immersion only the sample of Al-Cu
alloy was changed by a pure Al metal and its potential behaviour was followed against time. The curves
exhibit similar features as that recorded in curves of Fig. (2) during addition of 0.4 - 5 ppm CuCl
where the values of initial and final steady state potentials are approximately the same. These results
confirm that the release of Cu from the Al-3.84% Cu alloy seems to be enough not only to cause
enrichment on the alloy surface but also to dissolve and deposit on pure Al electrode. The above results
can further be confirmed by immersing two specimens of Al-3.84% Cu alloy and pure Al metal
separately in the same solution of 0.1M HCl. The variation of the potential against time of each one was
followed as represented in Fig. (4). The curve of pure Al shows that after shifted to more negative
potential with time, the potential change its direction and increases to less negative values with a smallar
rate as a result of the deposition of Cu from solution. A higher rate of increasing in potential is recorded
after around 65 days where the potential jumped to –100mV, which represent nearly the same steady
state potential of Cu metal of Fig. (1). This indicates that after around 65 days the surface becomes
completely covered with Cu therefore, the Al electrode behaves as a Cu metal. The small degree of
oscillation, which is recorded in case of pure Al, is due to the continuous deposition of Cu at the whole
surface as shown from examination of the surface using SEM.
Additionally, the behaviour of the Al-3.84% Cu alloy shows a higher degree of oscillation and
no achievement the potential of Cu metal (Fig.4). This result is due to the localized attack, which is
recorded by the SEM as to be discussed latter.
3.2 Scanning Electron Microscopy Examination
At the end of the experiments of Fig. (4), the surface topography of pure Al and Al-3.84% Cu
alloy was examined using SEM, the micrographs are given in Fig. (5). The scanning electron
micrographs of Fig. (5) indicate that, in case of pure Al (Fig. 5a) a fine redeposition of Cu is extended to
cover all the surface. In the case of Al-3.84% Cu (Fig. 5b) the surface became uneven where the Cu
present on the surface is not due to the Cu redeposition only but it is occur as result of the outer
diffusion or segregation of Cu to the surface. The alloy surface shows a severe attack besides the
enrichment of Cu as Cu clusters (as represented by the white and gray regions on the photograph). On
the other hand, the scanning micrograph at higher magnification (Fig. 5c) shows the appearance of
metallic copper on pure Al, which cover all the surface with no local attack and no copper cluster on the
surface. This observation confirms the result of the open circuit potential of Fig. (4), which shows a
higher shift in the potential of pure Al to attain nearly the steady state potential of Cu metal.
The higher magnification image of Al-3.84% Cu alloy (Fig. 5d) after immersion in 0.1 M HCl
for 80 days displays the formation of a uneven distribution film besides the appearance of copper
clusters which is grew to cover around 75% of the alloy surface. Additionally, a severe local attack also
occurred around the clusters which represent the dark region around the white or gray regions (cluster).
These results further support the result of Fig. (4), where a higher oscillation in the potential of Al-Cu
alloy is observed.
3.3 AES and XPS surface analysis measurements
The resulting surface of pure Al and Al-Cu alloy at the end of the experiments of Fig. (4) also
were examined using AES and XPS surface analysis techniques indicate that.
(1) The picture of the surface topography on the spectrometer for pure Al sample after
equilibration show nearly the same regular surface (its picture is not including in the present
(2) The AES survey analysis of pure Al of Fig. (7a), which is similar to many survey at different
sites on the surface, show the appearance of a peaks corresponding to Cu and oxygen and a trace
amount of C while Al peak is not recorded. This confirms that the surface of pure Al is nearly
completely covered by the deposited copper.
On the other hand the picture of the surface topography of Al-Cu alloy at the end
of experiment of Fig. (4), which also is not including in the photograph, is characterized by.
(1) The appearance of a white bright region which is surrounded by a dark regions
(similar to that recorded in Fig. (5)).
(2) The AES survey of the corresponding surface of Al-Cu alloy at the end of
experiment of Fig. (4) show different species which differ from site to another
depending on the bright and dark regions. Accordingly AES survey point analysis
was made at the same time on the dark and bright region as shown in Fig. (7b, c). The
spectrum of Fig. (7b) in dark region indicates that, the detection of Cu and O with
small amount which associated with the presence of excess Al. In contrast Fig. (7c) in
bright region (copper cluster) represent the appearance of Cu as major constituent
beside a traces amount of Al and O.
To throw more light on the surface composition XPS surface analysis Fig. (8) of pure
Al at the end of experiments of Fig. (4) indicates that copper is detected on the surface
mainly as copper metal (Cuo) and the 2P Cu of Fig. (8a) clear prominent contribution to the
2P3/2 and 2P1/2 also the shack up satellite has occurred as a result of the presence of Cu++. A
strong support of the previously recorded divalent copper came from Cu (LMM) spectra in
Fig. (8b) which shows the appearance of CuCl and CuCl2 beside the metallic copper (Cuo).
The enrichment of Cu in Al-Cu alloys has been extensively studied by several authors [8, 16, 19,
25-28]. Such enrichments can occure when amorphous Al oxides grow on the alloy surface [10,29,30]
to form the enriched layer, which contains copper clusters. The mechanism of the enrichment shows
some controversy [12,20,31], where it occurs either by a dissolution and redeposition process or by the
solid state enrichment followed by a non-faradic transport process. Recently, Afseth et al  concluded
that the enrichment of copper in solid solution is attributed to the selective dissolution of Al to lead the
formation of copper particles.
In the present study, the potential-time measurements carried out in 0.1 M HCl containing
different addition of CuCl 2, Fig. (2), show that the OCP drifted to less negative values in comparison
with pure Al. This shift is due to the accumulation of Cu metal on the pure Al surface in accordance
with mixed-potential theory.
Further confirmation on the accumulation of Cu metal on the Al surface at two different OCP
value (E = -860, -680 mV) are shown in Fig. (6). Both these values show a significant change of the
surface oxide film. The addition of 200 ppm CuCl 2 at these two values caused abrupt attendant positive
shift in the OCP to the same value. This indicates that the driving force for deposition of copper is the
same at these two values and the deposition of copper occurs from the first instant of immersion.
Previous result , concluded that the driving force for copper deposition is increased as the negativity
of the corrosion potential increases. This occurred when Al was immersed in a solution of 0.1 M
Na2SO4 in the presence of 10-3 M CuSO4.
On the other hand, our results of Figs. (3,4) provide an evidence to support the simple homogeneous
dissolution mechanism, where the surface of pure Al shows a higher accumulation of Cu on the surface.
The deposition of Cu on the surface of pure Al occurred where the colour of metallic copper clearly
detected by naked eye. This is agreement with a previous published data , which concluded that
copper can deposited at all sites even over the primary deposited Cu locations. This was behind the
positive shift in the OCP of pure Al to reach relatively the OCP of pure Cu metal (Fig. 4). This
conclusion is supported by AES survey analysis on the test coupons at the end of experiment of Fig. (4)
to allow quantitative identification of elements present at particular point on the surface to a depth of 5
um. The AES survey analysis is presented in Fig. (7a) which indicate that the peak related to Cu at 920
had increased in length to become maximum while Al peak at 1396 eV was not detected at that stage.
The selection of Al peak at 1396 eV for this study is occur because it is difficult to separate the Al and
Cu peaks either by XPS or AES owing to the overlapping of the minor peak of Cu with the main peak of
On the other hand the Al-Cu alloy in the same solution at the end of of Fig. (4) and the photograph of
Fig. (5) show different features. The final OCP shows higher oscillation rate at more negative OCP and
the surface at the end of the experiment show a severe attack around the Cu-clusters as represented in
the dark regions of photograph of Fig. (5d). To confirm these results and to identify the constituent
elements, it is possible through this versatility of the AES spectrometer to direct the electron beam to
specific points of the film, survey analysis was performed both in dark and white regions. The spectra
shown in Fig. (7b) in dark region show a very weak Cu signal beside Al and O shows enhanced signal
and the presence of C peak as a result of the adsorbed hydrocarbon formed from air atmosphere. On the
other hand the spectra in white region (inside the cluster) of Fig. (7c) shows that the Cu peaks become
maximum and also the presence of a weak peaks of Al and O. The presence of Al and O in the white
region (inside the cluster) are due to the thin nature of Cu cluster, which allow the electron beam to
detect Al and O from the Al2O3 underneath the Cu cluster. According to the results obtained from the
OCP, SEM and AES survey point analysis it can be concluded that a sever galvanic attack around the
cluster is occurred. The galvanic dissolution at the breifery of the Cu cluster can be extended to dissolve
the Al beneath the Cu cluster and caused detachment of some of these clusters from the alloy substrate
to solution as shown in photograph of Fig. (5d) at the right upper part. Missert et al  found that the
Al beneath the Cu rich island dissolves with crevice geometry. Once these clusters are detached from
the alloy surface it can be oxidized in the freely aerated HCl solution and finally deposited as Cu metal
on the alloy surface. The deposition of Cu metal on the pure Al surface shows fine deposits, which will
occur in the same manner on the alloy surface. This is in agreement with the published data , which
showed that the presence of Cl- ion promotes more uniform deposition of Cu on Al-Cu alloy surface. At
the locations of these uniform depositions of Cu and under the influence of acidity, the deposited Cu at
the outer most surface can be oxidized to Cu+ ions. This simple cuprous (Cu+) can not exist in aqueous
solution since it oxidizes and reduces itself through the reaction known as disproportionation [34-35].
2Cu+ = Cu2+ + Cu
This disproportionation reaction which takes place, for example, when Cu 2O is placed in a solution of
sulfuric acid can be hindered when Cu
is stabilized by the formation of insoluble substances or
complex ions. For instance, in the presence of chloride ion Cl
is stabilized through formation of CuCl
and CuCl2- . Under the present condition the medium has a high chloride content and any produced
Cu+ would be stabilized through formation of CuCl precipitate and CuCl
solution complex and the
disproportionation reaction appears unlikely to occur as represented in equation (1). Thus Cu
and Cl -
ions can come indirect contact only at the outer most surface where the surface of Al become
completely covered with Cu deposited, at the end of experiment of Fig. (4), as followed by the reactions
described bellow [35, 36].
Cu = Cu+ + e
Cu+ + Cl- = CuCl
CuCl + Cl- = CuCl-2
A feature support to the above was gained from XPS multiplex of the pure Al sample after treated in
0.1M HCl for 85 days at the end of experiment of Fig. (4) as represented In Fig. (8 ). The higher
resolution multiplex show that Cu
was detect in the Fig. (8a ), it is clear that the predominant
contribution to the 2P 3/2 and 2P 1/2 peaks and also the shack up satellite peaks at about 943 and 963 eV
occurred as a result of the presence of Cu++. The detection of Cu++ at the outer most surface facilitate the
second oxidation state of the Cu deposited. This conclusion is supported by the XPS composite of Cu
LMM spectra of Fig. (8b) for the same sample at the end of experiment of Fig. (4). The Cu LMM peak
indicate that the appearance of metallic copper (Cu
) at 334.8 and CuCl at 336.3 and CuCl
which are in agreement previously . The detection of metallic copper besides the first and oxidation
state on the surface satisfied the occurrence of the disproportionation reaction as shown in equation (1).
Finally, from the above studies it is concluded that the copper can be release to the solution through the
formation of dichloro coprate complex CuCl
of equation (4) and the disproportionation reaction as
shown in equation (1).
Two different types of Cu are detected; one of them is accumulated on the surface in the form of
clusters, which is responsible of the local attack. This was attributed to the AES survey point analysis at
two different point which indicate that Cu is accumulated in the bright white region (cluster) while in
dark region Al was present with higher ratio and traces Cu amount. The second is enriched on the surface
with a fine uniform redeposition. The redeposition of Cu on the pure Al surface represent an increase in
the potential of Al to less negative values to show the potential of pure Cu after about 65 days of
immersion. This was supported by the detection of Cu peak and the disappearance of Al peak at all sites
on the surface using AES survey point analysis. On the other hand XPS analysis confirm the detection of
Cu species in the form of Cu
, CuCl and CuCl
and the peaks corresponding to Al species was not
detected at the whole surface. The detection of Cu ++ ion supports the occurrence of the disproportionation
reaction of Cu +because Cu ++ is one of its reaction products. The dissolution of the redeposit Cu at this
stage behaves as Cu metal and can suggest that it occur both through the disproportionation reaction of
Cu+ and the solution of CuCl-2 soluble complex at the outer surface
 H. Habzaki, K. Shimizu, M. A. Paez, P. Skeldon, G. E. Thompson, G. C. Wood, X.
Zhou, Surf. Interface Anal. 23 (1995) 892.
 X. Zhou, H. Habzaki, K. Shimizu, P. Skeldon, G. E. Thompson , G. C. Wood,
Thin Solid Films 293 (1997) 327.
 I. Pires,L. Quintino. C. M. Rangel, G. E. Thompson, P. Skeldon, X. Zhou, Trans. Inst.
Met. finish. 78 (2000) 179.
 H. Habzaki, K. Shimizu, P. Skeldon, G. E. Thompson, G. C. Wood, X. Zhou, Trans. Inst.
Met. finish. 75 (1997) 18.
 M. Seruga, D. Hasenay, J. appl. Electrochem. 31 (2001) 961
 B. Mazurkiewicz and A. Piotrowski, Corros. Sci. 23 (7) (1983) 697.
 C. A. Drewien, R. G. Buchheit, Issues for Conversion Coating of Al Alloys with
Hydrotalcite, Corrosion / 94, paper n.622, NACE International, Houston, TX (1994).
 Y. Liu, F.Colin, P. Skeldon, G. E. Thompson, H. Habzaki, K. Shimizu, Corros. Sci. 45
 A. J. Smith, T. Tran , M. S. Wainwright, J. Appl. Electrochem. 29 (1999) 1085.
 S. Garcia-Vergara, P. Skeldon, G. E. Thompson, P. Bailey. T.C.Q. Noakes, H. Habzaki,
K. Shimizu, Appl. Surf. Sci. 205 (2003) 121.
 R. G. Buchheit, J. Electrochem. Soc. 142 (1995) 3994.
 R. G. Buchheit, M. A. Martinez , L. P. Montes, J. Electrochem. Soc. 147 (1) (2000) 119.
 J. R. Scully, R. R. Frankenthal, K. J. Hanson, D. F. Siconolfi, J. D. Sinclair, J.
Electrochem. Soc. 137 (1990) 1373.
 J. R. Gavele and S.M. de DeMicheli, Corros. Sci. 17 (1970) 795.
 I. L. Muller, J. R. Galvele, Corros. Sci. 17 (1977) 179.
 R. G. Buchheit, R. K. Boger, Localized Corrosion Proceeding of the Research Topical
Symposium, Corrosion 2001 NACE, Houston TX (2001) P 265
 R. Newman, T. Leclere, Dealloying of Copper Redistribution During Corrosion of
Aluminum Alloy 2024, Abstract H 1.2. M RS Spring 2000 Meeting abstract, San
Francisco, CA. Warrendale, PA: Materials Research Society, 2000.
 M. B. Vukmirovic, N. V. Dimitrov, K. Sieradzki, Experimental Models and Analogues of
the Corrosion Behavior of Al 2024 –T3, Abstract 273, Meeting Abstracts; 198th Meeting
of the Electrochemical Society, Phoenix, AZ, Pennington, NJ; The Electrochemical
 A. Afseth, J. H. Nordlein, G. M. Scamans , K. Nisancioglu, Corros. Sci. 44 (2002) 2529.
 R. G. Buchheit, R. P. Grant, P. F. Hlava, B. Mckenzie , G. L. Zender, J. Electrochem.
Soc. 144 (8) (1997) 2621.
 N. Dimitrov, J. A. Mann. , K. Sieradzki, J. Electrochem. Soc. 146 (1) (1999) 98.
 H. A. El Shayeb, F.M. Abd El Wahab , S. Zein El Abedin, Br. Corros. J. 34 (1) (1999) 37
 T. M. Saber, A. A. El-Warraky, Br. Corros. J. 26 (1991) 279.
 U. R. Evans, An Introduction to metallic corrosion, Ed. Amold (1963) London P. 6s.
 R. G. Buchheit, R. K. Boger and M. W. Donohue, Electrochemical Society Proceeding of the
Symposium on seawater Corrosion, PV 99-26, the Electrochemical Society. INC., Pennington, NJ.
P. 205 (2000).
 R. G. Buchheit, L. P. Montes, M. A. Martinez, J. Micheal , P. F. Hlava, J.
Electrochem. Soc. 146
(12) (1999) 4424.
 C. Witt, C. A. Volkert , E. Arzt, Act Materialia 51 (2003) 49
 Y. Liu, E. A. Sultan, E. V. Koroleva, P. Skeldon, G. E. Thompson, X. Zhou, K. Shimizu,
H. Habazaki , Corros. Sci. 45 (2003) 789.
 C. E. Caicedo-Martinez, E. v. Koroleva, G. E. Thompson, P. Skeldon, K. Shimizu, G.
Hoellrigl, C. Campbell , E. Mc Alpine, Corros. Sci. 44 (2002) 2611.
 K. Shimizu, K. Kobayashi, G. E. Thompson, P. Skeldon , G. C. Wood, Corros. Sci. 39 (2)
 N. Dimitrov, J. A. Mann. A, K. Sieradzki, J. .Electrochem. Soc. 132 (1985) 2308.
 D. J. Blackwood , A. S. L. Chong, Br. Corros. J. 33 (3) (1998) 225
 N. Missert, K. A. Son, F. D. Wall, J. C. Barbour, J. P. Sullivan, K. R. Zavadil, R. G.
Copeland, M. A. Martinez, R. G. Buchheit, C. S. Jeffcoate, H.S. Isaacs, Electrochemical
Society, Proceedings volume, 99-29, 1999 Pennington..
 M. J. Sienke and R. A. Plane “ chemical Principles and properties” 2nd Ed, MC GrawHill, London (1974) P; 540.
 A. A. El Warraky, J. Mater Sci. 31 (1996) 119
 A. A. El Warraky, Anti-Corros. Met. Mat. 50 (1) (2003) 40.
 A. A. El Warraky, A. E. El Melegy, Br. Corros. J. 37 (4) (2002) 305.
E / mVSCE
Al 3.84Cu alloy
Al 5.22Cu alloy
Al 11Cu alloy
100 120 140 160 180 200 220 240
Time / min
Fig. (1) Variation of the open- circuit potential of pure Al, Al-Cu alloys and pure Cu in 0.1 M HCl
solution of pH 1.
E / mVSCE
100 120 140 160 180 200 220 240
Time / min
Fig. (2) Variation of the open- circuit potential of pure Al in 0.1 M HCl of pH 1
in absence and presence of different additives of CuCl2.
E / mVSCE
Al after 2 hr.
Al after 4 hr.
Al after 8 hr.
100 120 140
Time / min
Fig. (3) Variation of the open- circuit potential of pure Al in 0.1 M HCl pH 1
Free from and contains dissolved product of Al-3.84 % Cu alloy after immersion in 0.1 M HCl for
E / mVSCE
Time / day
Fig. (4) Variation of the open- circuit potential of pure Al and Al-3.84 % Cu alloy separately in the
same corrosion cell containing 0.1 M HCl of pH 1 for 80 days.
E / mVSCE
after add. 200 ppm CuCl
at 140 min
after add. 200 ppm CuCl
at 13 min
100 120 140 160 180 200 220 240
Time / min
Fig. (6) Variation of the open- circuit potential of pure Al in 0.1 M HCl where CuCl2 are added at two
different values of potential.
Fig. (7) AES survey analysis of films formed on test coupon after immersion in 0.1 M HCl for 80 days,
at the end of experiment of Fig. (4).
(a) Pure Al
(b) Al-3.84 % Cu alloy in dark region
(c) Al-3.84 % Cu alloy in bright white region (cluster)
Fig. (8) XPS spectra for Cu after immersion of pure Al in 0.1 M HCl for 80 days, at the end of XPS of
(b) Cu LMM