Optimization of Strength-Electrical Conductivity
Properties in Al–2Fe Alloy by Severe Plastic
Deformation and Heat Treatment
Andrey E Medvedev,* Maxim Y Murashkin, Nariman A Enikeev, Ruslan Z Valiev,
Peter D Hodgson, and Rimma Lapovok
High-pressure torsion at room temperature followed by two processing
routes, either 1) annealing at 200
C for 8 h or 2) elevated temperature
C) high-pressure torsion, are employed to obtain simultaneous increase
in mechanical strength and electrical conductivity of Al–2 wt%Fe. The
comparative study of microstructure, particle distribution, mechanical proper-
ties, and electrical conductivity for both processing routes gives the optimal
combination of high mechanical strength and high electrical conductivity in
Al–2Fe alloy. It is shown that while the mechanical strength is approximately
the same for both processing routes (>320 MPa), high-pressure torsion at
elevated temperature results in higher conductivity (!52% IACS) due to
reduction of Fe solute atom concentration in Al matrix compared to
annealing treatment. High-pressure torsion at 200
C has been demonstrated
as a new and effective way for obtaining combination of high mechanical
strength and electrical conductivity in Al–Fe alloys.
The increasing of aluminum alloys’ strength without signiﬁcant
sacriﬁce in electrical conductivity is a current trend in industry.
With this in mind, ﬁnding ways to simultaneously improve
mechanical and electrical properties is important. This combi-
nation is essential for creating new lightweight conductive
materials for the electrical industry based on ultra-ﬁne grained
(UFG) Al–Fe alloys.
Aluminum alloys, particularly Al–Fe alloys, have several
advantages as conductive materials. Firstly, aluminum and iron
are very common and cheap metals, which
make them economically attractive. More-
over, bauxite ore contains up to 5% iron,
which means that alloying is not needed.
Secondly, solubility of iron in aluminum
for conventionally processed alloys at
room, and up to near-melting, temper-
atures is close to zero.
This eliminates the
major contributor to electrical resistivity,
that is, solid solute atoms (the other
contributors are grain boundaries, par-
ticles, and dislocation density).
The combination of these two factors
makes Al–Fe alloys valuable for weight-
saving applications in automobile or aero-
methods of treatment, such as casting and
subsequent drawing, provide a medium
level of strength and conductivity, where
strength is not sufﬁcient for high mechan-
ical loading applications.
Multiple publications have demonstrated that severe plastic
deformation (SPD) methods provide signiﬁcant strengthening
of Al–Fe alloys.
This strengthening results from the
combined effect of grain reﬁnement,
rated solid solution (SSSS) of Fe in Al, and reﬁnement of
intermetallic particles during deformation.
have also shown that artiﬁcial aging after high-pressure torsion
(HPT) increases both conductivity and tensile strength to the
level of 49–51% IACS and above 300 MPa, respectively.
Decomposition of supersaturated solid solution, that takes place
during aging, leaves the clean aluminum matrix with ﬁne
intermetallic particles, which simultaneously enhance alloy
conductivity and strength. It was shown that Al–11 wt% Fe alloy,
subjected to HPT with subsequent annealing at 100
C for 12 h,
had a microhardness up to 3020 MPa (314 HV) due to the
decomposition of supersaturated solid solution and precipitation
However, such annealing takes a long time to
complete and the decomposition of supersaturated solid solution
during annealing was not studied.
The more efﬁcient treatment, as shown for Al–Mg–Si alloy, is the
SPD at elevated temperatures, which initiates simultaneous grain
reﬁnement and dynamic aging. This leads to supersaturated solid
solution decomposition and nanoscale particle precipitation.
Comparative study of two processing routes (HPT at room
temperature and thermal treatment versus HPT at room
A. Medvedev, Prof. P. D Hodgson, Prof. R. Lapovok
Institute for Frontier Materials, Deakin University, Waurn Ponds,
Victoria, 3216, Australia
A. Medvedev, Dr. M. Y. Murashkin, Dr. N. A. Enikeev,
Prof. R. Z. Valiev
Institute of Physics of Advanced Materials, Ufa State Aviation
Technical University, Ufa, 450000, Russia
Dr. M. Y. Murashkin, Dr. N. A. Enikeev, Prof. R. Z. Valiev
Laboratory for Mechanics of Bulk Nanostructured Materials, Saint
Petersburg State University, Saint Petersburg, 198504, Russia
The ORCID identification number(s) for the author(s) of this article
can be found under https://doi.org/10.1002/adem.201700867.
Adv. Eng. Mater. 2018, 20, 1700867 © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
1700867 (1 of 7)