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RESEARCH
special

2 AluReport 03.2012
Content
03.2012
04 Interview
Advanced materials
Priv.Doz. Dr. Helmut Kaufmann,
Univ.Prof. Dr. Peter J. Uggowitzer
06 Automotive
High-strength sheets for lightweight applications
10 Automotive
High-strength material for heat exchanger applications
12 Aircraft
Advanced alloy AA6061-T6*
14 Automotive
Recycling alloys for structural parts
16 Science
AlSi-cast alloys
19 Awards
Awards for AMAG-PhD student
06 - 11 Automotive
16 Science
Imprint: AMAG Austria Metall AG, P.O. Box 3, 5282 Ranshofen, Austria, T +43 7722 801 0, F +43 7722 809 498,
md-amag@amag.at, www.amag.at, Bilder: AMAG Austria Metall AG, Design: Rauscher & Partner, Salzburg

Editorial
Dear Readers,
Valued Customers and Partners,
"If you don't go forward, you go backwards" - This is exactly what
AMAG has in mind right now. The first stage of the large-scale
"AMAG 2014" investment project - the new logistics center - was
completed on schedule and went into operation in November; and
there are a large number of other investments that are beyond the
scope of this issue. We will, of course, give a detailed account in
future AluReport issues.
But what are new, state-of-the-art production facilities without the
corresponding new products? Fortunately, special products are an
extraordinarily large proportion of AMAG’s product portfolio and will
continue to be so in the future.
This requires detailed knowledge of the production processes, such
as casting, with special strength in recycling, rolling and heat treatment
- know-how typical of the integrated location of Ranshofen.
We use that know-how in our research work when it comes to developing
new, innovative products. We have dedicated this issue of
AluReport to research in order to share with you some highlights of
our work in this field.
AMAG TopForm ® UHS and AMAG TopClad ® UHS are high-strength
aluminium materials which are mainly used in the automotive industry
and contribute to the weight reduction of components.
Or take, for example, recycled cast alloys for automotive structural
components, which, just like high-strength materials, contribute
towards reducing CO 2 -emissions in the production and use of automobiles.
AMAG has developed a new special alloy to meet the
demand of the aircraft industry for ever more lightweight aluminium
materials of high strength. Information on the resulting advantages
is provided on page 12.
Our specialists' expertise and close cooperation with our customers,
as well as with external research institutions and universities, enable
us to meet complex application requirements and to provide tailored
solutions. In this context, I am particularly pleased to learn that one
of our doctoral candidates has received several awards for the quality
of his work. More details are provided in the last article of this
AluReport.
I trust this issue shows AMAG in a slightly different light, and I hope
you enjoy reading it.
Gerhard Falch
Chief Executive Officer

4 AluReport 03.2012
Interview
Advanced materials –
tomorrow is already here
Priv.Doz. Dr. Helmut Kaufmann, COO Professor Dr. Peter J. Uggowitzer
AluReport talked with Professor Dr. Peter J. Uggowitzer from the ETH Zurich, Member of the Supervisory
Board and Chairman of the Scientific Advisory Board of AMAG, and with Chief Operating
Officer Dr. Helmut Kaufmann, about the future requirements for advanced materials. A lot of
research has brought AMAG one step closer to the future.
AluRep: Mr. Kaufmann, you were one of the initiators of the
„Light Metals Technology (LMT)“ Conference. In July 2013, this
conference cycle is going to celebrate its tenth anniversary in
London. What in your opinion has significantly changed in
these ten years of research on light metals? Please tell us the
key milestone in development.
Kaufmann: I can only answer this question from a subjective and very
personal point of view. Peter Uggowitzer and I already demanded in
our joint book on metallurgy and processing of high-integrity light metal
pressure castings of 2007 [1] that, following the „decade of mechanical
engineering“ in pressure casting, we put more focus on the material itself.
Meanwhile, AMAG, for which I have been working for more than five
years now, has adopted this approach in all aspects of product development.
AMAG produces recycled cast alloys for shape casting and rolled
semis, such as plates and sheets. AMAG is thus a material manufacturer
in the widest sense and should concentrate on the material.
As a result of a better understanding of the processes going on in aluminium
alloys during the individual production steps, during storage or
subsequent use and of their impact on the product properties, production
facilities and process control now must meet more stringent requirements.
The equipment must be adjusted to the material requirements and
not the opposite.
I see this „process chain approach“, with a process chain extending from
melting, continuous casting and rolling to the necessary heat treatment
and surface treatment steps, which is always focused on the material, as
the most important step in development over the past decade.
Uggowitzer: From a university researcher‘s point of view, I would like
to add that a number of simulation programs such as Pandat, Thermo-
Calc, DICTRA and MatCalc today enable us to investigate, the influence
of different alloy compositions on the individual microstructure and on
the properties to predict, fairly precisely, the constitution and treatment
required for the material in order to achieve the target properties. This
optimization requires coordinated process control along the entire production
route.
AluRep.: What are the consequences of these developments?
Uggowitzer: As we gained a better understanding of the relationships
between the alloy composition, process control and product properties,
we were in a position to design materials according to the specific
application requirements and to actively influence the properties. We
have learned that minor fluctuations in the alloy composition may lead
to major changes in the properties of cast and wrought materials or
components. Combined with increased customer requirements, this has
probably doubled the number of specific alloy grades.
Today, it is not enough to roughly specify an alloy according to standard,
for instance, automotive skin alloy AA6016 or recycled die-casting alloy
A226, and the heat treatment, such as the T6 treatment according
to the „Aluminiumtaschenbuch“ handbook. With a view to the desired
property profile, a fine tuning must be performed within the standard
composition, which, in turn, requires a precise adjustment of the thermomechanical
treatment. The precise tailoring of alloys, however, re-

quires a deep understanding of microstructural relationships. Through
its cooperation with a number of academic research institutions, AMAG
has, figuratively speaking, grown from a dwarf to a giant in this field over
the past five years. In my capacity as Chairman of the Scientific Advisory
Board, I think it is quite remarkable that in that period more than
50 scientific articles from the environment of AMAG were published in
international magazines.
AluRep: Let us take a look into the future. What megatrend
do you anticipate for aluminium products during the next decade?
Kaufmann: The aluminium industry cannot escape the great global
challenges, such as scarcity of resources and global warming. As a
result, new tasks will have to be performed along the entire process
chain in order to increase efficiency, and many new applications will
emerge from the range of positive properties of aluminium alloys. The
need for pushing lightweight construction will be a strong driver for new
applications and growth in volumes of aluminium alloys.
Users and developers will be faced with a new area of conflicting priorities,
which will require them to build up a cooperative partnership in
development to find a compromise solution. The trend towards alloys
and processes that are even more precisely adjusted to the individual
application in order to tap to the full the respective alloy potential, as
just described by Peter Uggowitzer, will lead to even narrower tolerance
limits for the alloy composition and the process parameters. Contrary
to that, the recycling proportion in high-grade cast and rolled products
is expected to continuously grow. It will be necessary, for economic
and ecological reasons, to extend the alloy limits as far as possible for
easier recycling, whereas the opposite will happen if we try to optimize
individual properties. In the final analysis, however, the wide variety of
aluminium alloys will become even wider.
Uggowitzer: Additionally, it is essential to keep optimized lightweight
construction affordable by using improved aluminium alloys. To me, this
means that improved alloys must be capable of being produced and
recycled on a commercial scale. Using very expensive elements such as
scandium and lithium in aluminium alloys cannot be the solution for extensive
optimization and, in the long run, will be economically reasonable
in special applications only.
Interview AluReport 03.2012 5
Our most recent work gives us a vision of the groups of alloys. Let
us have a look at the two age-hardenable alloy families, AA7xxx and
AA6xxx, which are AlZnCu and AlMgSi alloys. Both alloy families have
great potential for lightweight construction but also several deficiencies.
The AA7xxx group of high-strength alloys has its weak spot in the corrosion
properties, and a combination of strength and ductility is desired
for the AA6xxx family. Our studies on the interaction between vacancies
and the main alloying elements and special micro-alloying elements, that
is, alloying elements added in homoeopathic doses, have led us to believe
that it should be possible to significantly improve intercrystalline
corrosion and, in particular, stress corrosion in 7xxx alloys by selecting
an appropriately modified alloy composition without adding exotic, expensive
alloying elements. For 6xxx alloys, we expect the mechanical
properties to be improved by substantially shortening the duration of
thermal treatment.
If the theoretical concept of the „vacancy prison“ and the „vacancy drag“
can be put into practice, as intimated, I guess I know the answer to the
question concerning the great achievements of the past decade that
might be asked in 2022. Dr. Pogatscher received several awards for the
scientific works on this subject (see article on page 19).
AluRep: For a company like AMAG, the research work done to
arrive at the concept of the „vacancy prison“ and/or „vacancy
drag“ is surprisingly basic-oriented; what is to be expected in
the future?
Kaufmann: As already mentioned, AMAG is a material manufacturer
in the widest sense and sees itself as a premium provider of recycled
cast alloys and rolled semis. Therefore, our customers should not be
surprised—on the contrary, they should expect AMAG to do more than
just scratch the surface in research. This issue of AluReport is intended
to make clear that we supply many industries with a variety of aluminium
products and also commit ourselves to research in all product
segments. For what it‘s worth, I believe that basic-oriented research
work is essential to achieve the significant improvements that we all
need to meet the great global challenges of the near future. We can
be optimistic about the future if we are all committed and cooperate
towards product improvement and increase in efficiency.
I would like to give you an impressive example of an optimization along
the process chain: In 1886, when the Hall-Héroult process for the
production of primary aluminium was invented, 55 kWh was required
to produce 1 kg of primary aluminium from alumina by fused-salt electrolysis.
In 1950, approximately 25 kWh/kg was required, and today‘s
modern plants need less than 13 kWh/kg [2,3].
Literature:
[1] H. Kaufmann, P.J. Uggowitzer, „Metallurgy and Processing of High-Integrity Light Metal Pressure
Castings“, Schiele & Schön, Berlin, 2007, S. 2
[2] L. Marschall, “Aluminium – Metall der Moderne”, oekom, München, 2008, S. 200
[3] G. Djunkanovic, „Analysis of production costs in the aluminium smelting industry“, Aluminium
7-8/2012, S. 26-30

6 AluReport 03.2012
Automotive
7xxx-high strength aluminum
sheets for lightweight
automotive applications
Currently, for sheet applications in car
body engineering AlMg alloys of the
5xxx series or precipitation hardening
AlMgSi alloys of the 6xxx series
are used. The focus on lightweight design is
still increasing due to legislation and customer
requirements for less fuel consumption. Therefore
high strength AlZnMg(Cu) alloys of the
7xxx series with tensile strength up to 700
MPa are extensively discussed. The aerospace
and sports industry have been benefitting from
the utilization of these high strength alloys for
decades in terms of significant weight savings
and enhanced performance.
However a successful transfer to the automotive
industry requires innovative solutions to
allow cost-efficient series production. The pro-
posed solution is such that rolling, solution heat
treatment and artificial ageing shown in figure
1 are done at the rolling mill, while the components
are produced via warmforming at the
customer‘s site. Warm forming at temperature
levels far below those for press hardening steel
helps to overcome the moderate formability of
7xxx-alloys at RT.
High strength 7xxx series alloys of the type
AlZnMg(Cu) double the yield strength compared
to standard 6xxx series automotive alloys.
Both alloy families increase their strength
significantly by precipitation hardening. In a
continuous strip annealing line both alloy types
are solution heat treated and quenched to
freeze the supersaturated solid solution. Natural
ageing at room temperature starts and in
contrast to AlMgSi alloys formable for a couple
of months the hardening of AlZnMg(Cu) alloys
continues. Therefore, AMAG developed
a Cu-containing alloy called AMAG TopForm®
UHS for replacing press hardened steel in
automotive components like B-pillars or side
impact beams. It is an AA7075 type alloy
(AlZn5,5MgCu) optimized for warm forming
in the long-term stable T6 peak age delivery
temper. Higher strength compared to Cu-free
derivatives combined with controlled solution
annealing, quenching and artificial ageing at
aircraft certified continuous coil treating lines
ensure reproducible constant properties and
reduce the investments and processes needed
at the car manufacturer.

Warm Forming and Paint Bake
Response
Cold forming of artificially aged AA7075 in temper
T6 is limited to rather simple geometries,
e.g. roll forming with radii according to stringers
in the aircraft industry. For complex components
warm forming is recommended.
Based on FEM simulation results the parameters
for warm forming at a pilot press line were
adjusted. The plane 7xxx-blank was heated up
to the warm forming temperature within a minute
in a simple hydraulic press in direct contact
to hot plates. Short process times and a low
process temperature of around 200°C are essential
to keep the decrease of strength due to
overaging as small as possible.
400°C
200°C
20°C
Solution
Annealing
minutes
Water
Quench
Rolling Mill
Artificial Ageing
hours
Figure 1: Temperature-time-diagram for high strength 7xxx series alloys
Automotive AluReport 03.2012 7
Costumer
Warm
Forming
minutes

8 AluReport 03.2012
Automotive
The forming limit curves (FLC) in Figure 2
compare the formability of AMAG TopForm ®
UHS at different temperatures around 200°C
with the standard cold forming procedure of a
typical AA6016 automotive alloy in temper T4.
As already mentioned, cold forming of an
AA7075 T6 sheet is limited to rather simple
geometries. At 170°C the forming limit curve
comes close to the AA6016 T4 curve especially
for plain strain conditions. A further
increase to 230°C improves the formability
significantly and even for the stretch-forming
path AMAG TopForm ® UHS reaches the
formability of AA6016 T4 in cold forming.
On a pilot warm forming line a small series of a
structural component, similar to a side impact
beam of an automotive door was produced at
a Tier 1 automotive supplier in co-operation
with AMAG (Figure 3). This process proved to
be robust with very small variation of mechanical
properties after forming and painting.
While a variation of the warm forming temperature
leads to different mechanical properties
after the press shop, after the additional heat
treatment in the paint shop the final material
properties are very uniform. Figure 4 compares
the tensile and yield strength after warm
forming and after an additional heat treatment
in the paint shop.
While warm forming at 170°C with just one
or two minutes process time has almost no
impact on strength, a slight increase to 200°C
reduces the strength by some 50 MPa. Typically
a common 5-step paint-bake cycle for
drying the body-in-white structure, e-coating
and curing the various paint layers enables
re-aging. About altogether one hour heating
with a temperature collective of 125 to 185°C
with intermediate cooling to room temperature
leads to a yield-strength of 460 MPa.
major strain 1
0,7
0,6
0,5
0,4
0,3
0,2
0,1
0,0
-0,3 -0,2 -0,1 0,0 0,1
0,2 0,3 0,4 0,5 0,6 0,7
minor strain 2
sheet thickness 2 mm
AMAG TopForm ® UHS T6 - 230°C
AMAG TopForm ® UHS T6 - 170°C
AMAG TopForm ® UHS T6 - 20°C
6016 T4 - 20°C
Figure 2: Forming limit diagram for AMAG TopForm ® UHS at different temperatures vs. AA6016 T4
Figure 3: Side impact protection made from AMAG TopForm ® UHS
R m ,R p0,2 [MPa]
600
500
400
300
200
100
0
R m [MPa] R p0,2 [MPa]
After Warmforming
Figure 4: Warm forming plus 5-step paint bake cycle for AMAG TopForm ® UHS
After Warmforming
and 5 Times Paint-Bake Cycle

Figure 5: Resistance spot welded (Fronius Deltaspot®) AMAG TopForm® UHS cross die
From the customers point of view the process
starts with well defined and long-term stable
properties of AMAG TopForm ® UHS sheet.
During warm forming in the customer‘s press
shop and the susequent paint bake cycle the
mechanical properties of the component become
uniform on a high level.
Parameter fluctuations of time and temperature
during warm forming do not result in fluctuations
of the material properties after forming
and painting (Figure 4).
It was also observed that the springback after
warm forming is low because of the significantly
reduced yield strength at forming temperture.
Joining
Conventional fusion welding of copper containing
7xxx series is difficult due to the occurrence
of solidification cracks. For AMAG
TopForm ® UHS two modified thermal joining
methods were tested on a laboratory scale.
Resistance spot welding trials with the already
commercially available Fronius Deltaspot
® technology show very promising results.
Thereby two cross die parts with a drawing
depth of approx. 50 mm, derived from a 2 mm
AMAG TopForm ® UHS sheet, were produced
and joined (Figure 5). Detailed results will be
presented in the next AluReport 1/2013.
Additionally, AMAG TopForm ® UHS was successfully
joined with Friction Stir Spot Welding
(FSSW). This is a modification of the wellknown
FSW process resulting in round joining
spots. A process innovation of the company
RIFTEC with a segmented rotating tool
fills the deepening of the spots leading to a
smooth surface. This improved joining method
shows promising results for overlap joints of
AA7075 sheets.
The aircraft industry has a positive long-term
experience with mechanical joining methods
(e.g. riveting) of 7xxx series Al-alloys which
are also applicable to AMAG TopForm ® UHS.
Automotive specialties like self piercing rivets
or flow drill screws should also work but have
to be adapted from low and medium strength
aluminium to high strength 7xxx series alloys.
Adhesive bonding is another widely spread
joining technology used for aluminium in the
aerospace industry. In recent years this type of
Customer Benefits
AMAG TopForm ® UHS doubles the strength
compared to a standard AA6016 alloy.
Therefore a high specific resistance to denting
and high specific crash performance
make this alloy ideal for the replacement
of press hardened steels e.g. in side impact
protections or bumper beams. AMAG
TopForm ® UHS is an AA7075 type alloy
(AlZn5,5MgCu) optimized for excellent
warm forming behaviour at temperatures
between 170 and 230°C.
While time consuming process steps at high
temperatures like solution annealing and artificial
ageing are done in the rolling mill in an
efficient and controlled manner it just takes
seconds in the press shop to heat up the
blank to a temperature of around 200°C.
Furthermore the customer benefits from the
Automotive AluReport 03.2012 9
joining became popular in car manufacturing
especially in multimaterial car body designs.
Galvanic isolation of materials with different
electrochemical potentials and the prevention
of crevice corrosion is an important factor for
this type of joining. For a sufficient degradation
performance of the bond, the surface has
to be properly prepared.
Adhesive bonding pre-treatment in the aircraft
industry is based on batch wise anodizing
procedures for structural parts exhibiting
excellent tensile shear strength and fracture
pattern. So far, new pre-treatments show
comparable good results on a laboratory scale
and tests on AMAG’s modern and flexible
continuous automotive pre-treatment line will
follow soon.
fact that there is no requirement of rapid
quenching after warm forming.
A reliable and stable heat treatment process
at the rolling mill provides long-term stable
mechanical delivery properties in T6 temper
and offers stable high level properties after
press and paint shop within a robust process
window. New innovative thermal joining
technologies recently introduced to the
automotive industry have been successfully
tested for this AMAG high strength alloy.
Moreover, mechanical methods and hybrid
joining in conjunction with adhesive bonding
extend the joining portfolio. AMAG Top-
Form ® UHS in combination with tailored
pre-treatments fully exploits the strength
potential of modern automotive adhesives.

10 AluReport 03.2012
Automotive
High-strength aluminium material
for light weight heat exchanger
applications
With the use of conventional brazing
materials the request of
automotive manufacturers for
lightweight materials for applications
in high-performance heat exchangers
with reduced volume and mass cannot be
achieved. As a result of the increase in operating
pressures, cooler manufacturers require
higher mechanical strength after brazing, good
and reproducible processing and forming characteristics
of the delivered semi product, as
well as excellent brazing results. Aluminium
brazing sheet typically consists of a core alloy
either of the AA3xxx- or of the AA6xxx- series
and a filler layer of an AA4xxx alloy, which
has a significantly lower melting range than
Yield strength R p0.2 [MPa]
150
125
100
75
50
25
0
Rp0,2 soft temper
Rp0,2 after brazing and 8 days age hardening
AMAG
TopClad
non-heat-treatable alloys
®
the core alloy. Alloys of the AA2xxx-series and
high strength materials such as AA7050 or
AA7075 have not been used as core material
for brazing sheets since their solidus/liquidus
temperatures are too low. In the early 1980s
LongLife alloys based on AA3xxx were developed
in order to meet the demands for higher
strength and improved corrosion resistance
prevailing at that time [1]. In the early 1990s
a multilayer material compound was presented
to enhance mechanical strength and corrosion
resistance of brazing sheet. The sacrificial anode
material enriched in magnesium and zinc
increases the strength of the 3xxx core alloy
by diffusion phenomena [2].
In Figure 1 typical mechanical properties of
AMAG TopClad
Long Life alloys
® LL
Figure 1: Yield strength R p0.2 of AMAG TopClad ® products
AMAG
TopClad ® AMAG
HS TopClad
heat-treatable alloys
® UHS
currently available brazing materials in pre-
and post braze condition are compared. The
post brazed yield strengths R p0,2 for standard
non-heat treatable 3xxx materials range from
35 to 55 MPa; the values for LongLife alloys
vary from 55 to 65 MPa. Depending on
the cooling rate after brazing heat treatable
6xxx series alloys achieve post brazed yield
strengths R p0,2 of 70 to 85 MPa in naturally
aged condition. The mechanical characteristics
of these materials are often insufficient
for the future stipulations of the automotive
industry. This article is based on the development
of a high-strength, heat treatable brazing
sheet with an AA7020 core alloy [3].
Characterization of AA7020
brazing sheet
The AA7020 alloy belongs to the heat treatable
Al-alloys and is characterized by high
static strength. The combination of zinc and
magnesium results in age hardening and
thus in strength levels which exceed those of
standard brazing alloys by far. The strength is
mainly a function of Zn and Mg; the aging effect
depends on the Zn/Mg ratio.
The chemical composition of AA7020 is given
in Table 1 [4, 5]. To prevent a detrimental
diffusion of Mg into the clad filler during brazing
on an additional cladding of an interlayer
is required. In this paper results with AA1050
interlayer are described.
Table 1: Chemical compositions of AA7020 and AA1050
designation %Si %Fe %Cu %Mn %Mg %Zn %Ti
AA7020 0.35 0.40 0.20 0.05 – 0.50 1.0 – 1.4 4.0 – 5.0 0.05
AA1050 0.25 0.40 0.05 0.05 0.05 0.07 0.05

Post-braze strength
Alloy AA7020 gains its high strength after brazing due to solution heat
treatment and natural aging. Parallel to joining during the brazing process
solution annealing also occurs at brazing temperature. Precipitates
are formed by nucleation and growth from a supersaturated solid
solution during room temperature aging. In order to achieve optimum
strength characteristics, the majority of heat treatable aluminium alloys
have to be subjected to solution annealing in a relatively narrow temperature
range, however, this does not apply to AA7020. This favorable
behavior allows optimized process control for both solution heat treatment
and brazing in a single heating operation. As the quenching sensitivity
of AA7020 is low, the cooling speed after brazing can be varied to
a high degree without subsequently affecting natural room temperature
age hardening.
R m , R p0,2 [MPa]
300
250
200
150
100
50
material thickness: 1,6 mm
Rp0.2 Rm A50
0
15
0 20 40 60 80 100 120 140 160 180 200 220 240
aging time [h]
45
40
35
30
25
20
R 50 [%]
Automotive AluReport 03.2012 11
As shown in Figure 2, the AA7020 material achieves a yield strength
R p0.2 of 65 MPa in soft temper, which after brazing can rise to over
140 MPa with ongoing room temperature aging. Higher strengths and
improved corrosion resistance are obtained by artificial aging at 115 to
130 °C.
Mechanical properties at elevated temperatures
After brazing (i.e. after solution heat treatment) heat exchangers are
exposed to temperatures up to 160 °C in service. To simulate the material
characteristics at operating temperatures artificial aging of AA7020
brazing sheet was initiated after 8 days of natural aging. These aging
curves are shown in Figure 3. At the very beginning of artificial aging the
strength drops due to a reversion process [4, 5]. Higher temperatures
and longer aging times lead to a loss of strength due to overaging.
(a) (b)
art. aging at 120 °C
400
50
art. aging at 160 °C
400
R m , R p0,2 [MPa]
350
300
250
200
150
100
50
0
0
140
120
100
80
60
40
20
Rm
aging time [h]
Rp0,2
A50
45
40
35
30
25
20
15
10
A 50 [%]
R m , R p0,2 [MPa]
350
300
250
200
150
100
50
0
0
140
120
100
80
60
40
20
Rm
aging time [h]
Figure 2: Natural age hardening process AA7020 brazing sheet Figure 3: Artificial age hardening of 1,6 mm AA7020 brazing sheet at
120°C (a) and 160 °C (b)
AA 1050
AA 7020
Figure 4: Proper
brazing results due
to sufficient AA1050
diffusion barrier
Customer benefits of AA7020 clad brazing
sheet for base plates
Alloy AA7020 exhibits proper shearing and stamping characteristics
and is hence a premium option for plate-type heat exchangers.
Oil coolers use planar base plates of AA3xxx-, AA5xxx- or AA6xxx-
Literature:
[1] Gray, A.; Aluminium in automotive heat exchangers – closing the technology gap, 8th international brazing seminar, 2004.
[2] Yamauchi, S., et al; Clad aluminum allay material having high strength and corrosion resistance for heat exchanger, US 5292595A, 1993.
[3] Hanko, G., et al; High strength aluminium brazing material for heat exchanger applications, ASST, 2012.
[4] Aluminium-properties and physical metallurgy, AMS, 2005, pp. 175-185.
[5] Aluminium handbook- fundamentals and materials, Aluminium Verlag, 1999, pp. 252-260.
Rp0,2
alloys in a thickness range of typically 2.5 to 6.5 mm which could
be reduced significantly by use of high strength AA7020 brazing
sheet. Due to the high hardness of ~55 HB in soft temper
the high strength material shows excellent scratch resistance
against mechanical defects. This property is advantageous especially
in the sealing area between the engine block and the oil cooler,
an area which is critical with respect to leakages (Figure 4).
All standard Al-Si filler alloys for vacuum and flux agent based brazing
processes can be cladded as long as the working temperature does
not exceed 600 °C. As demonstrated in Figure 4 the diffusion barrier
avoids the diffusion of Zn and Mg and also the melting of low melting
phases. The corrosion resistance of AA7020 brazing sheet for base
plates is sufficient since the diffusion barrier made from AA1050 with
more than 150 µm thickness also acts as a corrosion protection layer.
A50
50
45
40
35
30
25
20
15
10
A 50 [%]

12 AluReport 03.2012
Aircraft
AMAG ADVANCED AA6061 ALLOY
FOR AEROSPACE APPLICATIONS
Previous investigations [1-4] showed
for the alloy AA6061 that the artificial
aging response is adversely affected
by natural aging at room temperature. A suitable
pre-aging procedure at elevated temperatures
immediately after solution heat treatment
is effective in reducing the detrimental effects of
natural aging on the artificial aging kinetics. The
temper T4* produced hereby shows an increased
aging response and after artificial aging to
temper T6* exhibits a much higher level of mechanical
properties.
In the present work the effects of pre-aging
treatment are shown for alloy AA6061 in artificially
aged temper T6* in comparison to sheet
material manufactured without this additional
heat treatment cycle after solution annealing.
Both materials were characterized according to
(a)
(b)
Ultimate Tensile Strength [MPa]
Testing direction LT
Ultimate Tensile Strength [MPa]
Testing direction L
370
350
330
310
290
270
220 240 260 280 300 320
370
350
330
310
290
A-Basis, MMPDS
6061-T6
Yield Strength [MPa], Testing direction LT
conventional 6061-T6 pre-aged 6061-T6*
A-Basis, MMPDS
6061-T6
B-Basis,
MMPDS
6061-T6
B-Basis,
MMPDS
6061-T6
270
220 240 260 280 300 320
Yield Strength [MPa], Testing direction L
conventional 6061-T6 pre-aged 6061-T6*
Figure 1: Mechanical properties of conventional 6061-T6 and pre-aged 6061-T6*
compared to A- and B-values listed in MMPDS-04 [5], tested in direction (a) LT
and (b) L
A-Basis: At least 99 % of the population of values is expected to equal or exceed
the A-basis mechanical property allowable with a confidence of 95 %
B-Basis: At least 90 % of the population of values is expected to equal or exceed
the B-basis mechanical property allowable with a confidence of 95 %
testing requirements typical of applications in the
aircraft industry.
All investigated materials were produced from
the same melt with a chemical composition within
the tolerance limits of AA6061.
Results
The significantly higher strength of pre-aged
6061-T6* compared to conventional 6061-
T6 is a result of the pre-aging treatment performed
directly after solution heat treatment
which has to be applied within a limited time
interval after quenching [2, 3]. Both ultimate
tensile strength and yield strength of the preaged
6061-T6* clearly exceed the A-and Bvalue
basis listed in the MMPDS-04 Handbook
[5] for AA6061-T6 sheet material, so that the
A- and B-values could be increased for future
aircraft applications when this enhanced pre-
da/dN [ mm / Zyklus ]
1,0E-01
1,0E-02
1,0E-03
aged 6061 material is applied (see Figure 1).
Fatigue crack growth
The results of the dynamic tests are shown in
Figure 2. Both AA6061 heat treatment variations
generally show a satisfying crack growth
rate, fulfilling also the requirements which apply
to the most common skin quality alloy in
the aircraft business AA2024-T3. In addition
to the higher strength level of the pre-aged
6061-T6* alloy, also the fatigue crack growth
rate is lower and therefore better than that of
the conventional 6061-T6.
The results of the fracture toughness test are
listed in Table I. The higher strength pre-aged
6061-T6* shows both for K C and K app higher
values compared to conventional 6061-T6,
but is slightly below the alloy AA2024-T3.
Fatigue Crack propagation in T-L direction
1,0E-04
5 10 15 20 25 30 35 40 45 50
ΔK [ MPa*m1/2 ]
Typical Limit - AA2024-T3
conventional 6061-T6
pre-aged 6061-T6*
Figure 2: Fatigue crack propagation plot of conventional 6061-T6 and pre-aged
6061-T6*, compared to the typical limit curve for the most common aircraft skin
quality alloy AA2024-T3, testing direction T-L (test according to ASTM E647 with a
160 mm wide center-notch sample and a stress ratio R = 0.1)
6061-T6
conventional
6061-T6*
pre-aged
AA2024-T3
typical
KC [MPa m1/2 ] 134 138 156
Kapp [MPa m1/2 ] 84 85 99
Table 1: Plane-stress fracture toughness Kc and apparent fracture toughness Kapp of
conventional 6061-T6 and preaged 6061-T6* compared to typical values of AA2024-
T3

Discussion
The increased mechanical properties in peak aged temper T6* go
along with enhanced fracture toughness values as well as with a lower
fatigue crack propagation rate, but without any negative influence on
corrosion resistance [1]. It is assumed that the co-clusters formed during
pre-aging exceed the criticallly stable size and, therefore, act as
nuclei for ß``-precipitates resulting in an increased number density of
this hardening phase in the microstructure [1, 4].
(a)
400
380
360
340
320
300
(b)
Ultimate Tensile Strength
[MPa]
conventional 6061
pre-aged 6061
Expected, Advanced
AA6061
Aircraft AluReport 03.2012 13
Figure 3: (a) Ultimate Tensile Strength and (b) Yield Strength of conventional 6061-T6 and pre-aged 6061-T6* compared to “Expected, Advanced AA6061-T6*”, tested
in direction LT and L The mentioned “expected” values of advanced AA6061 are based on laboratory investigations and have not yet been verified on industrial scale
Density
[g/cm³]
2,80
2,75
2,70
2,65
Testing direction Testing direction
LT
L
333 332
350 357
370 – 390 370 – 390
AA2024 2,78
conventional AA6061
2,70
Advanced AA6061 2,69
3,2% Density
reduction
Figure 4: Density of aerospace standard alloy AA2024-T3 in comparison to
AA6061 and AMAG Advanced AA6061
Customer Benefits
With AMAG Advanced AA6061-T6* even a further increase in mechanical
properties can be attained with optimized thermo mechanical
treatment after solution heat treatment (see Figure 3).
AMAG Advanced AA6061-T6*,with optimized chemical properties,
furthermore offers a density reduction of 3.2 % in comparison to the
aerospace standard alloy AA2024-T3 (see Figure 4). At a value of 2.69
kg/dm³, the density of AMAG Advanced AA6061-T6* is on a level comparable
with 3rd generation of aluminium lithium alloys (e.g. AA2198).
Yield Strength
[MPa]
360
340
320
300
280
260
conventional 6061
pre-aged 6061
Expected, Advanced
AA6061
Fatigue Crack
propagation, T-L
+/-0%
Fracture toughness, T-L
-11%
Testing direction Testing direction
LT
L
290 291
304 308
330 – 355 330 – 355
Density
-13%
-11%
Ultimate Tensile
Strength, LT
+11%
Yield Strength, LT
Baseline: Alclad AA2024-T3 AMAG Advanced 6061-T6*
Figure 5: Summarized comparison of typical properties of Alclad 2024-T3 with
AMAG Advanced 6061-T6*
AMAG Advanced AA6061-T6* has been optimized for high static strength making its mechanical properties comparable with various high strength
2xxx-series aluminium alloys, but offering superior corrosion resistance. Therefore, there is no need for a clad version which deteriorates the attainable
mechanical properties. AMAG Advanced AA6061-T6* attains a level of mechanical properties which make it even comparable to Alclad 2024-T3
(see Figure 5).
The advanced AA6061-T6* sheet material just presented can be produced in series by AMAG in thicknesses of up to 6,35 mm (0.250 inch) thanks to
additional heat-treatment equipment already integrated in the existing production line. It offers a density level as low as some AlLi-alloys but certainly
at a lower price and it can be recycled with conventional technologies in place around the world.
Literature:
[1] J. Berneder, R. Prillhofer, P. Schulz, C. Melzer: “Characterization of pre-aged AA6061-T6 sheet material for aerospace applications”, 13th International Conference on Aluminium Alloys (ICAA13), TMS (The
Minerals, Metals & Materials Society), pp. 1797-1802, 2012 [2] C. Zelger, J. Schnitzlbaumer, R. Prillhofer, J. Enser, C. Melzer: „Optimized Heat treatment sequences for AA6061“, Supplemental Proceedings, Volume
1, Materials Processing and Properties, TMS (The Minerals, Metals & Materials Society), 2010 [3] C. Zelger, P. Oberhauser, C. Melzer, P. Schulz: „Advanced 6xxx alloys for electronic applications“, Proceedings of EMC
2009, pp. 1419-1425, 2009 [4] J. Berneder, R. Prillhofer, J. Enser, P. Schulz and C. Melzer: Study of the artificial aging kinetics of different AA6013-T4 heat treatment conditions, Supplemental Proceedings: Volume
2: Materials Fabrication, Properties, Characterization and Modeling, TMS (The Minerals, Metals & Materials Society), pp 321-328, 2011 [5] MMPDS-04: Metallic Materials Properties Development and Standardization
(MMPDS), Battelle Memorial Institute, 2004

14 AluReport 03.2012
Automotive
Recycled Cast Alloys for Auto-
motive Structural Components
Until recently, recycled cast alloys
were neglected for use in crashrelevant
automotive structural
components as these alloys were
considered to be too brittle, particularly because
of their higher contents of iron and other
tramp elements. Already in the past five years,
AMAG carried out several investigations of Al-
Si9Cu3 alloy to demonstrate that this is a prejudice
and not universally applicable but rather
that remarkably good elongation values can be
achieved even with increased iron contents if
the proper alloy composition is chosen [1–3].
Based on that knowledge, in particular of the
interaction between alloying elements, it was
just logical to extend the work to other alloys in
the Al-Si-Mg system, focusing on the resource-saving
production of modern automobiles.
Following an analysis of CO 2 -emissions of
automobiles in service (where lightweight
construction has a favorable effect), automotive
manufacturers are increasingly investigating
also the carbon dioxide emissions produced
during automotive manufacture, attempting to
reduce these emissions according to a comprehensive
approach.
AUDI AG and AMAG are jointly addressing
this issue by developing recycled cast alloys
for structural components, which so far have
been made from primary cast alloys [4]. With
respect to the mechanical properties, this
fast-growing components segment especially
calls for high elongation values to absorb as
much energy as possible in case of a crash. To
date, this demand has been met by using lowporous
castings manufactured by vacuumassisted
pressure die casting processes, as
well as by using mainly primary, heat-treatable
aluminium alloys.
Automobiles are becoming more efficient and
emit less and less CO 2 in service, so it is essential
to take into account the expenditure of
energy during manufacture. Ideally, emissions
from an electric vehicle in service will be very
low as it is powered by renewable energies,
whereas more greenhouse gases are produced
during its manufacture compared to a
similar vehicle that is powered by an internal
combustion engine [5].
Accordingly, a next logical step in automotive
manufacture is to use components made from
recycled material. The terms "scrap", "recy-
Tolerance acc. specification and its expansions
cling" and "recycled material content" are defined
in detail in standard EN ISO 14021:2001
[6]. AMAG calculates the scrap portions of its
alloys (= recycled material content) in strict
compliance with this standard.
Apart from the iron content mentioned above,
recycled alloys contain other tramp elements
that are bound to occur in scrap processing.
Cu and Zn, as well as elements such as Bi,
Cr, Ni, Sb and Sn, must be taken into account
because they may have an adverse impact
on the desired alloy properties. Therefore, it
is essential to define the upper limits of these
elements on the basis of metallurgical knowledge
and joint discussion with the user in such
a manner as to not lose the desired properties
of the alloy and to not prevent, through unnecessary
restrictions, a high scrap charge rate
being applied.
It is not only the scrap portion that is defined by
the quantity of admissible trace elements, but
acc. EN 1706 Cu, Fe, Zn
Cu, Fe, Zn + Tramp
elements
Primary ingot > 60 < 30 < 10
Alloying elements 10 10 10
Scraps < 30 > 60 > 80
Table 1: Charge rates of ingots, alloying elements and scraps as a function of the specification. Values at defined charge
(scrap availability) rounded to 5 %; as of Dezember 2012.

Fig. 1: Examples of scrap charge in recycled alloys:
a) Clean, pressed foil and sheet packs sorted by
type, with defined compositions. b) Aluminium chips
contaminated by oil or emulsion from machining,
partly mixed with other materials.
also the type of input material. Table 1 shows
the possible starting material in the production
of structural cast alloy EN AC-43500 according
to DIN EN 1706:2010 [7], the starting
material used in case of tolerance extension
for iron, copper and zinc (however, with low
contents of trace elements, similar to a primary
alloy) and that used with a jointly defined tole-
(a)
(b)
Fig. 2 a: Microsection of a pressure die cast plate with
coarse primary Al-Fe-Mn phases.
Fig. 2 b: Microsection of a pressure die cast plate with
small, finely and uniformly distributed primary Al-Fe-
Mn phases. This promising alloy has an optimum Fe/
Mn ratio and was cast with adjusted process parameters
suitable for series production.
(a)
rance for trace elements as a function of the
elements, in a range where no adverse impact
on the performance of the alloy is observed
yet.
To ensure the desired scrap charge rate for
a standard-production component, it is important
to estimate the envisaged annual output
and to define the time frame for production.
These factors must be known to guarantee the
type, quality, quantity and availability of the required
scrap (Fig. 1).
To experimentally verify variations of alloys that
were theoretically optimized by computer simulation,
real recycled alloys were produced,
cast into plates using a die casting machine
(Bühler Evolution 120, 1200t closing force) in
a series-production environment, and subsequently
heat-treated.
The encouraging results of the tests promise
that recycling-friendly structural cast alloys can
be processed in series if appropriate process
parameters are selected and the required crystalline
structure is obtained. In addition to the
secondary precipitates, also primary precipitates
in the microstructure are to be considered
(b)
Automotive AluReport 03.2012 15
because from a certain size, the latter have an
adverse impact, particularly on the elongation
values, for example, in the microstructure of
an Al-Si-Mg alloy with different iron and manganese
contents (Figs. 2a and 2b) [8].
The tests confirm that the use of recycled cast
alloys with high scrap charge rates in automotive
structural applications is technically feasible,
but calls for sophisticated scrap logistics
and scrap availability for industrially significant
quantities. Even demanding body parts can
be manufactured from these alloys, provided
the alloy supplier, the casting expert and the
designer (automotive manufacturer) closely
cooperate.
Recycled alloys contribute to lightening the
ecological backpack as early as at the stage
of manufacturing a component, in particular
with respect to greenhouse emissions [8]. However,
it is clear that the challenge of huge
growth in the volumes of cast and wrought alloys
in automotive construction cannot be met
solely by recycled alloys, but it is absolutely necessary
to use primary metal. The proportion of
recycled alloys in structural castings, however,
can be substantially increased when this alloy
development is successfully completed.
Literature:
[1] P. Pucher, H. Böttcher, J. Hübler, H. Kaufmann, H. Antrekowitsch and P. Uggowitzer: Einfluss der Legierungszusammensetzung auf das
Speisungsverhalten der Recyclinglegierung A226 (AlSi9Cu3) im Sand- und Kokillenguss, Giesserei 7 (2011), S. 26-37.
[2] P. Pucher, H. Antrekowitsch H. Böttcher, H. Kaufmann, P.J. Uggowitzer: Influence of compositional variations on microstructural evolution,
mechanical properties and fluidity of the secondary foundry alloy AlSi9Cu3. International Journal of Cast Metals Research 23 (2010), S. 375-383.
[3] P. Pucher, H. Antrekowitsch, H. Böttcher, H. Kaufmann, P.J. Uggowitzer: Einfluss der Legierungszusammensetzung auf die mechanischen
Eigenschaften der Sekundärlegierung A226 (AlSi9Cu3) im wärmebehandelten Zustand. Gießereipraxis 11 (2009), S. 354-358.
[4] P. Pucher, H. Böttcher, H. Kaufmann, H. Antrekowitsch und P. J. Uggowitzer: Einfluss der Legierungszusammensetzung auf die mechanischen
Eigenschaften und das Fließvermögen der Sekundärlegierung A226 (AlSi9Cu3). Gießereipraxis 3 (2009), S. 71-78.
[5] Fragner, Baumgartner, Suppan, Hummel, Bösch, Höppel, Uggowitzer: „Einsatz von Schrotten in Recyclinglegierungen für Strukturanwendungen
im Automobilbau“, 7. Ranshofener Leichtmetalltage, Gmunden 7.-8.11.2012, Energieeffiziente Mobilität, 72-73, ISBN-13: 978-3-
902092-07-6].
[6] „Broschüre zur Umweltbilanz des Audi A6 nach DIN EN ISO 14040“, zertifiziert durch TÜV NORD CERT, AUDI AG, Entwicklung Gesamtfahrzeug
und Kommunikation Produkt, Ingolstadt, 05/2011, Seiten 18-23 und 29;
[7] EN ISO 14021:2001 (D, E): „Umweltkennzeichnungen und -deklarationen – Umweltbezogene Anbietererklärungen (Umweltkennzeichnung
Typ II)“ Ausgabe: 2002-01-01, Österreichisches Normungsinstitut, Wien 2002 und Europäisches Komitee für Normung, Brüssel, 2001-08,
bes. Kapitel 7.8.1.1.
[8] DIN EN 1706:2010 (D): „Aluminium und Aluminium Legierungen – Gusstücke – Chemisches Zusammensetzung und mechanische Eigenschaften“
Deutsches Institut für Normung e.V., Berlin, 2010-06.
[9] Bösch, Höppel, Göken, Hummel, Uggowitzer: „Sekundäraluminium-Gusslegierungen für Strukturanwendungen in der Karosserie“, Große
Gießereitechnische Tagung 2012, Salzburg, 26-27. April 2012, Tagungsband, Seiten 52-53

16 AluReport 03.2012
Science
Influence of Main Alloying Elements on
Key Physical Properties of Heat-Resistant
Al-Si Cast Alloys
The January 2012 issue of AluReport
contained a detailed account of the
influence of Ni on the thermal conductivity
of heat-resistant Al cast alloys.
This article is intended to clarify the importance
of the alloying elements Si and Cu.
In addition to thermal conductivity, λ, the coefficient
of thermal expansion, α, plays a vital
role in the selection of alloys for motor components.
For example, materials that have
minimum thermal expansion are to be used
for drives to prevent the piston seizing in the
cylinder [1].
Amongst other things, understanding the
influence of the above alloying elements on
Fig. 1a: Influence of Si on the thermal conductivi-
ty λ at 40 °C [1] and comparison with values from
literature [2]
Fig. 1b: Influence of Si on the thermal expansion
coefficient α and comparison with values from literature
[7-9, 14]
thermal conductivity and the coefficient of
thermal expansion is a prerequisite for determining
useful concentrations in the relevant
alloys and/or estimating physical characteristics
in good approximation when the alloy
composition is known, thus AMAG is in a position
to increase its expertise in giving advice
to customers on key physical characteristics.
Thermal Conductivity
Fig. 1a shows the influence of Si on the thermal
conductivity of secondary Al alloys and
compares the measured data with literature
values [2] for pure aluminium.
To simplify matters, Al-Si alloys are considered
a sort of „composite material“ consi-
(a) (b)
Thermal Conductivity [W/ mK]
250
225
200
175
150
Zhang et al.
λ measured
0 5 10 15 20
Si-content [wt.-%]
sting of an Al matrix and eutectic silicon. The
value of such a material lies between the respective
values for the individual components
of the composite and can be estimated using
models [3, 4]. At a value of 25 W/mK [5,
6] for λ Si , the calculated values correspond
well with the measured values [1]. It should
be taken into account that AMAG did not
use a pure Al99.99 matrix when measuring
the influence of the alloying elements but an
AlFe0.4Mn0.3Mg0.35 base alloy that more
appropriately reflects the real composition of
a cast alloy made of recycled material.
α [x10 -6 K -1 ]
26
24
22
20
λ
gemessen
Hatch [9]
Rule of Mixtures [25]
Turner [26]
Kerner [28]
0 2 4 6 8 10 12
Si-content [wt%]

Fig. 2a shows the influence of Cu on the thermal
conductivity of hypoeutectic and near-eutectic
recycled Al alloys, where in both cases λ
decreases almost linearly as the Cu concentration
increases [1].
The investigated alloys contain 0.35% Mg
each, which results in type θ-Al2Cu and Q-
Al5Cu2Mg8Si7 secondary precipitates formed
during artificial aging, which reduce
thermal conductivity. In the hypoeutectic alloys,
all Mg and Cu is brought into solution by
a preceding annealing process at 495 °C. In
AlSi12Cu4(Mg), some of the Cu remains undissolved
during that solution treatment and
occurs in the form of primary Al2Cu phases
that have a more adverse impact on λ than dispersed
secondary phases, which explains the
(a) (b)
Thermal conductivity [W/ mK]
200
190
180
170
160
150
140
130
AlSi7 (Mg)
AISi12 (Mg)
0 1 2 3 4
Cu-content [wt.-%]
relatively sharper decrease in thermal conductivity
between 3 and 4 % Cu for the eutectic
variations [1].
Fig. 2b shows the influence of Ni on the thermal
conductivity of the alloys AlSi7(Mg) and
AlSi12(Mg). This coefficient decreases much
more sharply than for Cu as the Ni concentration
increases. The solubility of both Fe and Ni
in the α solid solution is negligible, so primary
phases (Al9FeNi and/or Al3Ni) containing Fe
and Ni will form even if the concentrations of
these elements are low, and the material character
will change from a „homogenous material“
to a more complex „composite material“
[10-13].
In that case, λ can also be estimated by ap-
Thermal conductivity [W/ mK]
200
190
180
170
160
150
140
130
AlSi7 (Mg)
AISi12 (Mg)
0 1 2 3
Ni-content [wt.-%]
Science AluReport 03.2012 17
proximation using the above models. A detailed
description of the procedure for modeling thermal
conductivity as a function of the Ni content
and/or the volume fraction of intermetallic phases
containing Ni has already been published
[11].
Coefficient of Thermal Expansion
Fig. 1b shows the effect of Si on the coefficient
of thermal expansion, α. Models to
estimate the α value of two-phase materials
provide an option to assess the influence of
silicon [7-9, 14].
Being below the resolution limit of the
measuring method employed in that work
(see Fig. 3), the separate influence of Cu and
Ni on α is relatively small, which is attributable
to the relatively small volume fractions of
secondary and/or primary phases formed by
separate addition of Cu or Ni. The coefficient
of thermal expansion does not significantly
change until the Cu and Ni contents become
extremely high [1].
Fig. 2: Influence of (a) Cu and (b) Ni on the thermal
conductivity λ of AlSi7(Mg) and AlSi12(Mg) [1]

18 AluReport 03.2012
α [x10 -6 K -1 ]
25
24
23
22
21
20
Science
(a) (b)
AlSi7 (Mg)
AISi12 (Mg)
0 1 2 3 4
Cu-Gehalt [Gew.-%]
Thermal Shock Resistance:
Despite the fact that no extensive measurements
of the thermal shock resistance were performed
in the context of that work, it is possible to rank
various alloys by their resistance to thermally induced
stresses by calculating the second thermal
shock parameter, R‘ S [1]:
1 – v W
R' = λ · σ · [ ]
s� krit
E · α m
Accordingly, the thermal shock parameter
describes the resistance of a material
to thermally induced cracking. The higher
the respective value, the less sensitive the
material to thermally induced stresses. It
thus becomes clear that under cycle thermal
loads, the susceptibility of a material to
failure increases as the high-temperature
strength and thermal conductivity decrease
and the coefficient of linear thermal
expansion increases [15].
Literature:
[1] F. Stadler, H. Antrekowitsch, W. Fragner, H. Kaufmann, E. Pinatel und P. J. Uggowitzer: The effect of main alloying elements on the
physical properties of Al-Si foundry alloys, Materials Science and Engineering A, 560 (2013), 481-491.
[2] Y. Zhang, X. Wang und J. Wu: The Influence of Silicon Content on the Thermal Conductivity of Al-Si/Diamond Composites. In: International
Conference on Electronic Packaging Technology & High Density Packaging (ICEPT-HDP), Beijing (2009), 708-712.
[3] J. E. Parrott und A. D. Stuckes: Thermal conductivity of solids, London: Pion Limited (1975).
[4] Z. Hashin: Analysis of composite materials - a survey, Journal of Applied Mechanics, 50 (1983), 481-505.
[5] L. Wei, M. Vaudin, C. S. Hwang und G. White: Heat conduction in silicon thin films: Effect of microstructure, Journal of Materials Research,
10, No. 8 (2012), 1889-1896.
[6] S. Uma, A. D. McConnell, M. Ashegi, K. Kurabayashi und K. E. Goodson: Temperature-Dependent Thermal Conductivity of Undoped
Polycrystalline Silicon Layers, International Journal of Thermophysics, 22, No. 2 (2001), 605-616.
[7] N. Chawla und K. K. Chawla: Metal Matrix Composites, New York: Springer (2006).
[8] P. S. Turner: Thermal-Expansion Stresses in Reinforced Plastics, Modern Plastics, 24 (1946), 153-157.
[9] E. H. Kerner: The Elastic and Thermo-Elastic Properties of Composite Media, Proceedings of the Physical Society Section B, 69 (1956),
808-813.
[10] Z. Asghar, G. Requena und F. Kubel: The role of Ni and Fe aluminides on the elevated temperature strength of an AlSi12 alloy, Materials
Science and Engineering A, 527 (2010), 5691-5698.
[11] F. Stadler, H. Antrekowitsch, W. Fragner, H. Kaufmann und P. J. Uggowitzer: The effect of Nickel on the thermal conductivity of Al-Si cast
alloys. In: 13th International Conference on Aluminum Alloys (ICAA13), TMS (The Minerals, M. &. M. S. (Hrsg.). Pittsburgh: TMS (11121),
137-142.
[12] F. Stadler, H. Antrekowitsch, W. Fragner, H. Kaufmann und P. J. Uggowitzer: Der Einfluss von Nickel auf die Warmfestigkeit von AlSi-
Gusslegierungen, Giesserei, 98 (2011), 26-31.
[13] F. Stadler, H. Antrekowitsch, W. Fragner, H. Kaufmann und P. J. Uggowitzer: The effect of Ni on the high-temperature strength of Al-Si
cast alloys, Materials Science Forum, 690 (2011), 274-277.
[14] J. E. Hatch: Aluminium: properties and physical metallurgy, ASM (1988).
[15] Spörl, R.: Einfluss des Gefüges auf mechanische Festigkeit und dielektrische Eigenschaften von CVD Diamant. Forschungszentrum
Karlsruhe, Bericht (2002), (FZKA 6658), 16- 17.
α [x10 -6 K -1 ]
25
24
23
22
21
20
AlSi7 (Mg)
AISi12 (Mg)
0 1 2 3
Ni-content [wt.-%]
Fig. 3: Influence of (a) Cu and (b) Ni on the thermal
expansion coefficient of AlSi7(Mg) and AlSi12(Mg)
at 250°C [1]
Customer Benefit
Understanding the competing interactions
among the main alloying elements and their
influence on the mechanical and physical
properties are of fundamental importance
to developing and optimizing heat-resistant
alloys on the basis of recycling. It turns out
that using a large quantity of expensive alloying
elements such as copper and nickel
does not always yield better results. Additionally,
it is essential to focus not only on
strength but also on other characteristics
specific to alloys, such as thermal conductivity,
coefficient of thermal expansion
and thermal shock resistance. Depending
on the component and application, an improvement
of these properties can be more
effective and yield better results.
The comprehensive investigation of various
alloy variations, combined with a scientific
understanding of the mechanisms going
on, enables AMAG to tailor an optimum solution
according to the customer‘s needs,
while at the same time identifying cost optimization
potentials for existing solutions.

Awards for AMAG
PhD student
Dr. Stefan Pogatscher receives awards in USA and Austria.
Stefan Pogatscher received the Acta
Materialia Student Award 2011 at
the MS&T meeting in Pittsburgh,
USA, for his publication „Mechanisms
controlling the artificial aging of Al-Mg-
Si Alloys“ [1] on 8th October 2012. The prize,
awarded annually by the highly respected
leading metallurgy journal Acta Materialia for
outstanding publications, is one of the most
important international accolades for PhD students
in materials science.
The paper, which also ranks among the „Top
25 Most Downloaded Articles 2011 „in Acta
Materialia, describes the effect of natural aging
on the artificial aging of Al-Mg-Si alloys, a topic
which has been discussed for more than 70
years. For the first time a strong temperature
dependence of the effect was shown, which
enabled the development of a new physical
model to understand the problem.
In addition to the fundamental character of the
paper, it was its crucial importance for the aluminium
industry that significantly contributed
to the decision of the committee. An application
of the theoretical background provides a
reduction in usual heat treatment times while
simultaneously increasing strength. The paper
originated during Stefan Pogatscher‘s work
on his thesis, which was supported, not only
financially, within the strategic development of
age-hardenable high strength aluminium alloys
by AMAG.
In addition to this international award won for
one of his publications, Stefan Pogatscher
also gained recognition for his thesis at the
national level. He received the University
Research Award of the Industry 2012 at the
Aula of the University of Graz on 30th of October
2012. This prize is awarded annually by
the Federation of Austrian Industries Styria
for PhD theses of outstanding scientific quality
submitted at one of the Styrian universities
that deal with industrial related problems and
yield high-potential results. The thesis written
in the course of a collaboration between
Montanuniversitaet Leoben, ETH Zurich and
AMAG Austria Metall AG as industrial partner
covers a kinetic and imaging analysis of
aging processes in Al-Mg-Si alloys. The fact
that the newly developed model can now be
applied to answer important questions such
as the effect of storage at room temperature
is to be highlighted from an industrial point
of view. Based on the described principles
AMAG already developed several new industrial
heat treatment strategies and filed a patent
application.
Dr. Stefan Pogatscher receives the Acta Materialia
Student Award 2011 at the ASM Leadership
Awards Luncheon on 8th October 2012, David L.
Lawrence Convention Center, Pittsburgh, USA
Company AluReport 03.2012 19
Literature:
[1] S. Pogatscher, H. Antrekowitsch, H. Leitner, T. Ebner, und P.J.
Uggowitzer, Acta Mater, 59 (2011) 3352-3363.

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