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SAP and SAAs - Encyclopedia аl 13 thirteenth element moscow 2007 The rusal library Contents

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SAP and SAAs

The abbreviation SAP stands for “sintered aluminium
powder.” SAP is made by placing oxidized aluminium
powder in an aluminium hull and sintering it or heat-
ing it to a temperature slightly below the metal’s melt-
ing point. While it is still hot, SAP is pressed into
moulds to make semifinished products (bars). The
pressed material outwardly resembles a metal in that
it has a metallic luster, is fairly strong and conducts
heat and electricity. However, in contrast to metal,
SAP absorbs humidity well as it contains oxide parti-
cles. The bars can be pressed and rolled into sheets,
rods, and pipes. SAP is at its strongest when it con-
tains 25% aluminium oxide. Such material is six
times stronger than pure metal. SAP retains this prop-
erty even when it is heated to 500–600
ºC. For this
reason, it is used to make articles that are used in
high temperatures like car engine pistons. Sintering
aluminium alloy granules ranging from several
micrometres (10–3 mm) to several millimetres pro-
duces materials called “sintered aluminium alloys”
(SAAs) or granulated alloys. The initial granules are
made by dispersing liquid metal with a gas jet. SAAs
are obtained in a similar manner to SAPs: alloy pow-
ders and granules are heated in an aluminium hull and
then hot-pressed and extruded. The resulting material
has a fine-grained structure which makes it strong
and heat resistant and gives it a low friction coeffi-
cient. In many regards, SAAs have superior properties
to cast alloys of the same composition. For example,
granulated duralumin D16 is stronger than a cast bar
made of the same alloy as its structure contains small
particles, including phase strengtheners, which are
not present in the cast alloy. SAAs and SAP are widely
used in the car industry.  


N. America

Japan and 

W. Europe

S. Korea

and cardan drive
Steering System
Aluminium in the Automobile Components 
in the Industrially Developed Regions, kg per automobile
(source: “Urals Metal Market”)
Honda NSX
Porsche 928
Crystal structure 
of intermetallide MgZn

Aluminium. Thirteenth Element. 
Around Us
BMW Z4 has “thinned down” and now weighs 1,300 kg.
Several companies design cars with steel bodies which
have some parts made of aluminium alloys. Toyota, Ford
US and Porsche use the alloys to make doors, hoods,
roofs and boots. Ferrari, Aston Martin and Ford US have
actively implemented aluminium alloys to produce all
external panels of the body. In the United States alone,
the annual sales of cars with these panels exceeds $1.5
Cars with aluminium bodies are immune to corro-
sion and therefore can be used in any climate condi-
tions. Manufacturers use extrusion to reinforce
bumpers, protective blocks in the side doors, seat
frames, window frames, the aerodynamic spoiler, oil
duct, hydraulic conduit and the reservoir,. The products
are formed by pressuring softened aluminium through a
matrix with an opening of a certain section. Extrusion of
aluminium alloys can achieve a maximum size precision.
One New Zealand-based company recently used extru-
sion to make engine parts for internal combustion. Such
an engine weighs less, is more durable and works with less
noise than an engine made with traditional casting tech-
nologies. The sunken profile can produce engines with
various bucket speeds and numbers of cylinders.
Another promising method of manufacturing alu-
minium parts is powder metallurgy, or pressing materi-
als from powders and then firing them. In Japan, this
technology is used to prepare parts of the air condition-
ing’s compressor, buckets and cylinders.

Aluminium Alloys

Many alloys have been created using aluminium.
The addition of different metals (called “alloying ele-
ments”) to aluminium increases its strength and
improves its other properties. Aluminium alloys are
divided into two different types based on the method
of forming articles: casting alloys which are used for
casting articles in moulds, and wrought alloys which
are used for rolling and drawing.
Casting aluminium alloys are distinguished according
to their alloying elements. These may include silicon
and magnesium, silicon and copper, copper, and mag-
There are several different methods for casting articles
from of casting alloys. The simplest method is casting
into a die or a steel mould. It must be carried out in an
inert atmosphere, for molten aluminium oxidizes easi-
ly. A reciprocating pump can be used to make a lighter
porous article, as liquid metal foams when poured into
the mould. Pump bodies, among others, are cast in
this way. Another method is to make an exact model
of the intended article (e.g., compressor blades) out of
wax. The model is then blasted with ceramic powder,
which sticks to the wax and hardens, turning into a
durable heat-resistant crust. The model is then heated,
the molten wax is removed through a small hole, and
the aluminium is poured inside. This method is called
“lost-wax casting.” 
The most important aluminium casting alloys are sili-
con alloys or “silumins.” They are characterised by
good fluidity in the liquid state as they quickly and
completely fill moulds without forming cracks or bub-
bles. Different series of silumins are used for making
cylinder heads and blocks, fuel systems, and house-
hold items such as latches and coat hooks. If you
bend a coat hook with pliers it will crack: many cast-
ing alloys are fragile!
Magnesium is added to increase their strength which
leads to the formation of magnesium silicide crystals
which strengthen its structure. Several such alloys are
said to be heat-resistant, as they can withstand tem-
peratures of up to 400
ºC and are used 

Audi A8

Wheel disk made from
aluminium alloy
Many aluminium alloys are so elastic that when heated
they can significantly stretch. Thanks to this, parts with
complicated forms can be obtained from air-pressing
a flat metal sheet, which involves stretching the sheet
over the shape matrix or by a moving die which makes it
possible to create embossed parts with complex sections,
bumps, rivets and openings.
Many aluminium alloys are so malleable that they can
stretch considerably during heating. Thanks to this prop-
erty, parts with a complicated design can be made out of
a flat metallic sheet.
The use of aluminium in the automotive industry is
growing, but high cost is holding it back. A car with an
aluminium body is a luxury item. Its cost highly exceeds
a car of the same class with a steel body.
To repair an aluminium body is more expensive and
complicated than repairing a steel car. A minor dent can
be eliminated without difficulty, since aluminium is soft
and malleable. However, in the case of more serious dam-
age it is harder to return an all-aluminium body to its orig-
inal form. Only a special welding technology in an atmos-
phere of inert argon gas can be used on aluminium and
most repair centers do not have it at their disposal yet. 
About 10% of all aluminium produced is used in the

electronics industry

. This has an interesting history. In
the 1880s, the director of a train station in Chicago noted
that an external electric cable made from copper wire
quickly failed. Copper, as it turned out, was corroded by
substances in steam engine smoke. Several hundred

to cast engine crankcases and other parts working
under heavy loads.
Aluminium alloyed with silicon and copper is harder
and stronger due to the formation of not only magne-
sium silicide but also the intermetallic phase. Such
alloys are used to make instrument cases and for air
and car engines parts.
Even a small admixture of iron lowers the strength of
silumin and leads to the development of cracks. 
Alloys with over 10% of silicon are highly corrosion-
resistant and have good welding properties. If silumin
contains more than 13% silicon, the alloy loses its
strength and malleability but barely increases in vol-
ume when heated. The malleability of many silumins
can be increased by adding a minute amount (a few
hundredths of a percent) of sodium or phosphorous.
Aluminium and magnesium alloys are resistant to cor-
rosion, have a low density and are easily cut. Both of
the metals in this alloy oxidize easily so to avoid this,
the alloy is fused and poured in the presence of pro-
tective fluxes (substances that are specially added to
lower the melting point and remove existing admix-
tures). The alloy is then thermally treated to improve
its mechanical properties. Such alloys are highly
resistant to seawater and humidity which makes them
suitable for use in the shipbuilding, aircraft, and rocket
industries. They are used to make instruments, nose
and tail gear forks, and steering wheels.
Aluminium-copper alloys are difficult to cast and have
a low resistance to corrosion. They are also very
strong at normal and high temperatures and are easy
to cut and weld. They are used to cast load-bearing
Wrought aluminium alloys are easy to work for they
are strong and malleable. At the same time, they have
low liquidity and do not fill moulds completely.
Wrought alloys are denoted by special symbols con-
sisting of letters and digits. The letter at the beginning
of the symbol represents the type of alloy. For exam-
ple, D refers to a duralumin-type alloy, F to a forging
alloy, and H to a high-strength alloy. Commercial-
grade aluminium is denoted by the letter A. 
Aluminium-manganese alloy (AMn) is one of the most
widespread wrought alloys. This alloy is soft and mal-
leable yet insufficiently strong. The AMn alloy is used
for in construction and decoration as well as in manu-
facturing shop equipment and kitchenware.
Aluminium-magnesium alloys (AMg) are called mag-
naliums. The strongest alloy among them (AMg6) con-
tains approximately 6% magnesium as well as small
amounts of manganese, titanium, and beryllium. The
alloy is manufactured into different wrought semi-
 finished products such as sheets, panels, rods, and
sections, and is tough and resistant to corrosion. The
alloy AMg6 is easy to weld. It is used to make rocket
fuel tanks, gasoline and oil pipelines, ship hulls and
masts, hoisting crane parts, railroad car frames, and
car bodies. Experiments have even been made using
aluminium-magnesium alloys for infantry combat


Aluminium. Thirteenth Element. 
Around Us

These alloys are strong due to the formation of mag-
nesium silicide and ageing processes. The AV alloy
and other aluminium-magnesium-silicon alloys are
widely used in construction and vehicle engineering.
Their surfaces can be easily polished and anodised,
which makes them suitable for decorative purposes.
For this reason, aluminium-magnesium-silicon alloys
are used to make cases for watches and domestic
appliances. Other such alloys are used to make
pipes, forged products, and window frames. 
Forging alloys are elastic and resistant to cracking
during heat treatment. They have a similar chemical
composition to duralumins yet they contain more
 silicon. The AS8 alloy with approximately 4% copper
is used to make engine mounts, spar booms, and
other parts of modern aeroplanes. The AS6 alloy
which has a lower copper content is used for making
The addition of zinc, copper, and magnesium to
alloying elements produces high-strength alloys that
are employed in the aviation and defense industries.
They are used to make load-bearing parts, including
not only aircraft coverings but also bulkheads (trans-
verse bars in aeroplane hulls used for increasing the
strength and stability of the sidewalls and base),
stringers (longitudinal bars that serve as supports
for bulkheads), and spars (bars used for strengthen-
ing the wings). Modern alloys are fine “organisms”
whose properties are determined by the purity of the
initial substances and the meticulous execution of
the technology used to make them..
Alloys in which aluminium serves as the main
alloying element deserve a special mention. These
include aluminium bronze, aluminium brass, and
aluminium iron. Aluminium bronze was the first
aluminium alloy and replaced traditional tin bronze.
Today, bronzes with a 4–11% aluminium content
are used in industry. Alloys containing up to 7%
aluminium are elastic and can be pressure-treated.
Bronzes with a high aluminium content are not
 malleable and are used as casting alloys.

metres of copper wire were replaced with aluminium
wire. It admirably survived the test of time, even though
each year the number of trains on the line increased.
Aluminium wires successfully compete with tradi-
tional copper ones, as they are more than three times
lighter and much cheaper. The high electric conductiv-
ity of aluminium means that it can be used to prepare
bare cables for airborne electric wires, structural isolat-
ed communication cables, installation wires and wind-
ing wire. When conducting a current, bare cables heat
up and their surface becomes covered with a durable
film of oxide acting as an isolator which protects them
from external factors. Sometimes aluminium wires
anodise, or their surface becomes covered in a protec-
tive oxide film. These wires have such a high chemical
resistance that without prolonged isolation they can
work in high moisture climates and at temperatures
from –200°C to +500°C. 
Anodic oxide films are used in electric technology as
rectifiers. When they come in contact with a metal that
cannot be anodised, they form a system that lets current
through in one direction only or they act as rectifiers.
Aluminium is used to make various types of antennas,
including TV aerials and radars. Telephone operators
also need aluminium as it makes up telephone cables. 
In several countries aluminium is used to manufac-
ture mast supports for electric current lines. 


aluminium cars are used to transport
bauxite, alumina and grain, while aluminium cisterns
are used to transport acids.

vehicles: shells simply get lodged in the material
because of its toughness. 
Duralumins are the oldest aluminium alloys still used
in contemporary technology as they have an effec-
tive combination of strength and malleability. How-
ever, they are fragile and insufficiently resistant to
corrosion. The first such alloy was discovered in
1909 and is still used in technology. Duralumins are
widely used in aeronautics and until recently D 1 was
used to make aeroplane propeller blades. The best-
known alloy (D 16) is a still key material in aircraft
Duralumins become a lot stronger after ageing. In
so-called natural ageing, the alloy is kept exposed
for a long time and in the process copper gathers
in disc-shaped zones with a thickness of 1–3 atomic
layers and a diametre of 9 nm. Such zones are called


zones after two scientists who inde-
pendently discovered the accumulation of copper
in the structure of aged aluminium-copper alloys.
The concentration of copper in Guinier-Preston
zones is a lot higher than in the surrounding solid
solution. The number of such zones in a cubic cen-
timetre of alloy is extremely high: 5·10
. As copper
has a smaller atomic radius than aluminium, the
crystal lattice becomes deformed around Guinier-
Preston zones making the alloy stronger. 
Thermal treatment is also used to harden aluminium-
magnesium-silicon alloys. The American metallurgists

Z. Jeffries 


R. Archer 

made the first such alloy in
the 1920s and, in Russia, the well-known metallurgist
S.M. Voronov worked with them.  

Our priority development is permanent search to extend the usage of aluminium in a car in order to efficiently reduce its mass without negative impact
on its size and level of security. This is confirmed by the development of car industry in North America, where Alcan works successfully both with the
three leaders of American car manufacturers and with the foreign manufacturers in this region. At all events, aluminium is more and more used in cars,
in average, in the USA in 2003 128 kilos of aluminium were used compared with 87 kilos 10 years ago... The North American transport is the biggest
consumer of aluminium, it uses annually nearly 3.4 million tons of aluminium, out of which about 70% is spent on the production of cars.
Thomas Gannon, vice-president of the branch of industrial and automobile products of Alcan Corporation in Cleveland.
The argon-arc welding
1. Argon
2. Welding rod
3. Tungsten electrode
4. Electrical arc
The model of aging 
of the aluminium-copper
solid solution
Aluminium wire rod
Scheme of Guinier-
Preston zones

Aluminium. Thirteenth Element. 
Around Us

Aluminium bronzes surpass tin bronzes in many ways
as they have a high resistance to corrosion, including
in seawater. Articles made of aluminium bronze are
used in ships and aircrafts, chemical instruments, and
electric technology. Aluminium brass (a copper-zinc
alloy containing 1–4% aluminium) has similar uses.
Aluminium is also part of certain nickel alloys such as
Alumel which is heat resistant, elastic, easily forged
and drawn, and has magnetic properties. Alumel and
the chromium alloy Chromel have been used since the
1930s to manufacture thermocouples (devices for
measuring temperature).  

The use of all-aluminium vehicles in public transporta-
tion is not financially viable as a rule because of the alu-
minium’s high cost. In France, aluminium alloys are used
to make TGV high-speed trains carriages, which reach
speeds higher than 500 km/h. Steel parts are replaced
with aluminium ones in cars that operate in humid condi-
tions. Some Russian metro cars are made of aluminium
alloys. The difference in the mass of the aluminium and
steel versions of this car has been calculated at 3,620 kg,
which yields a considerable economizing effect during use. 
In ship building aluminium is used to made high-
speed vessels, like Russia’s “Raket”, “Meteor” and
“Vikhr”. Their production makes use of magnalium, an
aluminium-magnesium alloy. Aluminium alloys are used
to make the bodies of motor boats, yachts and deep-sea
vessels. One of the largest such yachts, the 90-metre-long
Afina, was built in 2004 from welded 10–15 mm thick
aluminium sheets. The same metal is used to make the
hulls of ocean liners. Aluminium was first used in ship-
building in 1893 when making a torpedo boat. 
Aluminium and its alloys are irreplaceable in the

chemical and fuel industries

to build vats and ducts
thanks to their resistance to many acids and alkalis. Alu-
minium alloys are essential in the serial production of
containers for concentrated nitric acid.
For pipelines, especially those in permafrost condi-
tions, aluminium-magnesium alloys are used. The
American company Noble Corporation has used alu-
minium to equip a pipe for deep-water drilling off the
shores of Brazil at depths of up to 1,300 metres. Overall,
the system was 45% lighter than the steel version. 
High-speed TGV train
“Meteor”, high-speed
hydrofoil boat

Aluminium. Thirteenth Element. 
Around Us
appeared on a church in Rome. Aluminium was very
gradually implemented for use in construction.
Some of the first weight-bearing constructions were
the beams and trusses of the Smithfield Bridge in Pitts-
burg (USA) originally made from steel, but in 1933
replaced with aluminium. The frequent use of anti-slick
products led to the corrosion of the aluminium struc-
ture, but nonetheless the beams lasted more than 30
years and were replaced with new ones from the same
material. However, the railings, which were processed
with reagents, have been kept in an excellent condition
until now proving the longevity of aluminium structures
where they are used properly. The reconstruction of the
Smithfield Bridge proved profitable, since the use of
aluminium decreased the bridge’s mass by 700 tons,
while the supports of the old bridge were used in the
construction of the new one.
In 1950 an aluminium bridge was built in Canada
across the Saginaw River. Its foundation has a pivotless arch
with uncut shore trestles. The bridge’s mass is 180 tons, but
this could have been lower if its heavy concrete surface had
been replaced with a lighter aluminium version.
Aluminium in Construction
hanks to its high durability, lightness, corrosion-
resistance, attractive appearance and resistance
to earthquakes, aluminium alloys are widely used
in construction. The minimum service period of alu-
minium constructions is estimated to be 80 years. They
resist climate effects and “work” in a wide range of tem-
peratures, from –80°C to +300°C (unlike steel, which
breaks down at low temperatures), which is especially
important in the Urals and Western Siberia. For some
constructions this factor is no less important than resist-
ance to corrosion or low mass. Although the flexibility
module of aluminium is less than the analogous figure
for steel as a result of its low density, an aluminium sheet
weighs half as much as an equally rigid steel plate. Accord-
ing to foreign scientists, the weight of an aluminium con-
struction is two or three times less than the weight of an
identical steel one, and up to seven times lighter than a
concrete construction with equal supportive capacity. 
Aluminium is employed virtually everywhere on
account of its excellent properties. Aluminium is used
to make frames and coverings for buildings and other
structures, including trusses, supports, columns,
bridge spans, roof and wall panels, architectural
details on façades and interiors, window frames,
doors, shutters, garden and balcony grates, parapets
and eaves. Each year around the world the volume of
high-rise construction increases. Contemporary
façades amd shopping, entertainment and office cen-
ters are built requiring new construction solutions. In
Europe over the last 40 years, the use of aluminium in
construction has increased by 15 times, and specialists
estimate that the demand will grow annually at least
2% to 3%.
Aluminium was first used in construction in 1896
when the Life Building in Montreal installed an alu-
minium cornice. A year later an aluminium roof

Drawbridges made out of aluminium alloys have
numerous advantages. They weight relatively little,
which makes the mechanical part simpler and lighter,
removes the need for bulky counterbalance, and offers
various new options for design. See for example a
bridge with an opening span in Sunderland Port, Eng-
land. It weights 95 tons less than a similar one made of
steel would. 
After World War II aluminium alloys were used in
the construction of high-rise buildings. In the 1950s

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