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Beryllium
Beryllium has one of the
highest melting points of the light metals.
The modulus of elasticity of beryllium is
approximately 1/3 greater than that of steel.
It has excellent thermal conductivity, is
nonmagnetic and resists attack by concentrated
nitric acid. It is highly permeable to X-rays,
and neutrons are liberated when it is hit
by alpha particles, as from radium or polonium
(about 30 neutrons/million alpha particles).
At standard temperature and pressures beryllium
resists oxidation when exposed to air (although
its ability to scratch glass is probably
due to the formation of a thin layer of
the oxide). Beryllium is a very light weight
metal with a high modulus of elasticity
(five times that of ultrahigh-strength steels),
high specific heat, and high specific strength
(strength to weight ratio).
Uses -
Beryllium is used as an
alloying agent in the production of beryllium-copper
because of its ability to absorb large amounts
of heat. Beryllium-copper alloys are used
in a wide variety of applications because
of their electrical and thermal conductivity,
high strength and hardness, nonmagnetic
properties, along with good corrosion and
fatigue resistance. These applications include
the making of spot-welding electrodes, springs,
non-sparking tools and electrical contacts.
Due to their stiffness,
light weight, and dimensional stability
over a wide temperature range, beryllium-copper
alloys are also used in the defense and
aerospace industries as light-weight structural
materials in high-speed aircraft, missiles,
space vehicles and communication satellites.
Thin sheets of beryllium foil are used with
X-ray detection diagnostics to filter out
visible light and allow only X-rays to be
detected.
In the field of X-ray lithography beryllium
is used for the reproduction of microscopic
integrated circuits.
Because it has a low thermal neutron absorption
cross section, the nuclear power industry
uses this metal in nuclear reactors as a
neutron reflector and moderator.
Beryllium is used in nuclear weapons for
similar reasons. For example, the critical
mass of a plutonium sphere is significantly
reduced if the plutonium is surrounded by
a beryllium shell.
It is, however, brittle, chemically reactive,
expensive to refine and form, and its impact
strength is low compared to values for most
other metals.
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