ISSN 1070-4272, Russian Journal of Applied Chemistry, 2008, Vol. 81, No. 5, pp. 796!799. + Pleiades Publishing, Ltd., 2008.
Original Russian Text + T.M. Umarova, I.N. Ganiev, 2008, published in Zhurnal Prikladnoi Khimii, 2008, Vol. 81, No. 5, pp. 761!764.
AND CORROSION PROTECTION OF METALS
Effect of Ytterbium on the Corrosion-Electrochemical Behavior
of Aluminum in a Neutral Medium
T. M. Umarova and I. N. Ganiev
Nikitin Institute of Chemistry, Academy of Sciences of Republic of Tajikistan, Dushanbe, Tajikistan
Received June 18, 2007
Abstract-Effect of ytterbium on the corrosion-electrochemical behavior of aluminum and an aluminum3
manganese alloy in a neutral 3% solution of NaCl was studied.
Ytterbium, one of the least widespread and worst
studied rare-earth elements of the yttrium group, is a
paramagnetic material that is easily mechanically
processed and has high electrical conductivity, which
exceeds that of other lanthanides by a factor of 3.
Ytterbium is weakly oxidized in air and is one of the
few rare-earth metals (REM) that have distinctive
properties, compared with other metals in this series.
For example, the structure of the electron shell of
elements in their metallic state largely predetermines
the physicochemical properties of a metal. With ex-
ception of ytterbium and europium, REMs (R) are
trivalent. Ytterbium exists also in the bivalent state
and, therefore, its properties in alloying can differ
from those of trivalent metals.
All the REMs (except ytterbium) have at room
temperature a close-packed hexagonal structure of
the magnesium type (A3), whereas ytterbium crys-
tallizes in a cubic face-centered lattice of the copper
type (A1) . In contrast to many REMs, ytterbium
has a comparatively low melting point (816oC),
which facilitates alloying .
The aim of this study was to examine the effect
of ytterbium on the corrosion-electrochemical
behavior of aluminum and an aluminum3manganese
alloy containing 1.9 wt % Mn in a 3% solution of
NaCl. This study continues previous investigations
 of the effect of alloying elements on the corro-
sion behavior of aluminum and alloys based on this
By now, there are no data on the corrosion
behavior of aluminum alloyed with ytterbium.
Therefore, the electrochemical behavior of alloys
containing up to 0.5% ytterbium was examined in
The alloys studied were prepared from aluminum
of A85 brand [GOST (State Standard) 4784374],
ytterbium of Itb M1 brand [TU (Technical Specific-
ation) 48-4-204372), and electrolytic manganese of
Mr00 brand (GOST 6008382). To study the corro-
sion behavior of aluminum3manganese alloys al-
loyed with ytterbium, alloys of the Al3Mn3Yb
system were synthesized from the corresponding ad-
dition alloys Al3Mn (10%) and Al3Yb (10%), which
made it possible to obtain alloys of homogeneous
chemical composition in the systems under study.
A molten aluminum alloy was poured into a steel
mold in order to obtain cylindrical rods 8 mm in
diameter and 100 mm long. The thus fabricated elec-
trodes were lapped, polished to mirror shine, and
washed and degreased with ethanol.
The study was performed using the experimental
procedure described in . A silver chloride elec-
trode served as reference in the electrochemical cell,
and a platinum electrode, as auxiliary electrode.
The solution temperature of 20oC was maintained
by a thermostat. The potential sweep rate was
, a 3% solution of sodium chloride served
as a corrosion medium. The electrodes were polar-
ized in the potentiostatic mode, with the potential
shifted in the anodic direction from the free-cor-
rosion potential (steady-state potential) to a constant
current of 2 mA and then backwards to a value of
31.6 V, after which an anodic curve was measured.
A full polarization curve is shown in Fig. 1.
The results of a potentiodynamic study of ytter-
bium-alloyed aluminum in a 3% solution of sodium
chloride are listed in Table 1. All the potentials are