C1aL14 Smart Alloys

Key Words

Alloys - metals mixed together to form a new metal

Deformed - shape is changed.

Nitinol - alloy between nickel and titanium

Original - shape a material started off with.

Properties - features of the element.

Shape memory - alloys return to their original shape after being deformed

Undeformed - material regains its original shape.

Grade E

We have seen how some metals need to be mixed with others to form alloys.  While many metals are deformed permanently when squashed pulled or hit, smart alloys regain their original shape.  This is called shape memory.  There are two main kinds of smart alloys:

• Copper-zinc-aluminium;
• Nickel titanium alloys (expensive), often called nitinol.

Grade C

Smart alloys exist in two different forms.  The change from one form to another can occur over a temperature difference as small as 5 ^oC.  If the metal is deformed by forces, and then heated, it goes back to its original shape.

Grade A

Smart alloys can be used to help patients with badly broken bones.  Metal plates are screwed in to compress the bones to help healing.  However with normal plates, the pressure wears off after a while.

A smart alloy is cooled to below body temperature and distorted.  As it goes back to its original shape, the bones are kept in compression and heal sooner.