ISSN 1070-4272, Russian Journal of Applied Chemistry, 2008, Vol. 81, No. 10, pp. 1785–1789. © Pleiades Publishing, Ltd., 2008.
Original Russian Text © T.M. Umarova, Z.S. Dzhalolova, I.N. Ganiev, 2008, published in Zhurnal Prikladnoi Khimii, 2008, Vol. 81, No. 10, pp. 1660–1665.
Effect of Rare-Earth Metals (Y, La, and Ce) on the Corrosion
and Mechanical Properties of Aluminum–Manganese Alloy
T. M. Umarova, Z. S. Dzhalolova, and I. N. Ganiev
Nikitin Institute of Chemistry, Academy of Sciences of the Republic of Tajikistan, Dushanbe, Tajikistan
Received May 14, 2007
Abstract—Effect of some rare-earth metals (yttrium, cerium, and lanthanum) on the corrosion-electrochemical
and mechanical properties of an aluminum–manganese alloy of eutectic composition (1.9% Mn) in a neutral
medium was studied.
Aluminum–manganese alloys are a well-known
construction material that is not hardenable by thermal
treatment and is distinguished by high plasticity, good
weldability, and high corrosion resistance. However,
alloys of the AMts type are subject to pitting corrosion
under certain conditions. Previously, the corrosion-
electrochemical behavior of Al–Mn alloys has been
studied in a wide range of concentrations [1–3].
Multicomponent systems with intermediate phases
belong to the most widely used and practically impor-
tant systems. The phase diagrams of these systems un-
derlie the technology for manufacture of alloys from
nonferrous metals and deformable half-products.
Therefore, studying these systems and revealing the
fundamental aspects of their structure is a topical task.
The aim of this study was to examine the effect of
rare-earth metals (REM), such as yttrium, cerium, and
lanthanum, on the corrosion-electrochemical behavior
of an aluminum–manganese alloy and to analyze its
mechanical properties. As a base material was chosen
an alloy of eutectic composition (Al + 1.9% Mn) as a
construction material with improved physicochemical
properties, compared with the industrial AMts alloy.
temperatures in the range 800–1000°C. Cylindrical
rods 8 mm in diameter and 100 mm long were cast in a
graphite mold from the alloys obtained. Before being
submerged in an electrochemical cell, the rods were
ground, polished, and degreased with ethanol.
The corrosion-electrochemical behavior of al-
loyed aluminum–manganese alloys was studied using
the method described in . The sequence of opera-
tions performed when measuring a polarization curve
is schematically shown in Fig. 1. The potential sweep
rate was 2 mV s
, a silver chloride electrode served as
reference, and the potentials were recalculated to the
standard hydrogen scale (s.h.e.). The corrosion rate K,
a function of the corrosion current density i
found by the formula
AND CORROSION PROTECTION OF METALS
To study the corrosion-electrochemical properties
of REM-containing aluminum alloys, addition alloys
were prepared from A995 aluminum [GOST (State
Standard) 11069–74], and alloys of prescribed compo-
sitions, from technical-grade aluminum of A8 brand
(GOST 4784–74*) in an SNVL–1.301 vacuum furnace
in corundum crucible in the atmosphere of argon at
Fig. 1. Schematic of the polarization curves of the alloys
under study. (E ) Potential and (i) current density.
K = i
where k is the electrochemical equivalent whose
numerical value for aluminum is 0.335 g A