it keeps its new shape until it is heated.
When the temperature is raised above a certain level
the alloy returns to its original shape.
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Smart Alloys.
A smart
alloy is a smart
material that can remember
its original shape.
The technical name for a smart alloy
is a shape memory alloy
(SMA).
Examples of this type of
alloy are nickel-titanium
copper-zinc-aluminium and copper-aluminium-nickel.
When a smart
alloy is bent or twisted (called deforming)
it keeps its new shape until it is heated.
When the temperature is raised above a certain level
the alloy returns to its original
shape.
Nickel-titanium smart
alloys are the most successful
but the most expensive. The material
is called Nitinol.
It is used to make dental braces and spectacle
frames.
Dental braces are wires
which are used to correct the
growth of teeth.
Nitinol can provide a constant force on the teeth
as it tries to return them to the correct
shape.
Spectacles are glasses which people use to see better.
The frames often get bent and
Nitinol frames can return to their
original shape on warming.
The disadvantages of smart
alloys are their high
cost
and their increased metal
fatigue.
Metal fatigue happens when bending or
twisting of a metal causes it to break.
Extraction of
Metals Alloys
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Copyright © 2008 Dr. Colin France. All Rights Reserved.