Video Transcript
Stents are put into constricted
blood vessels to reduce the effects of some chronic cardiovascular diseases. It is desirable to make stents from
highly flexible alloys that can return to one shape after being deformed. The alloys should also be resistant
to most forms of corrosion. Which of the following alloys is
the ideal choice for making stents? (A) Brass, (B) bronze, (C)
cupronickel, (D) cast iron, or (E) nitinol.
Alloys are metallic solid solutions
that contain a metal and at least one other element. Stents have to be made from an
alloy that is highly flexible so that it can return to one shape after being
deformed. They also have to be resistant to
most forms of corrosion because they are surrounded by bodily fluids, which might
increase corrosion. Brass, bronze, cupronickel, and
cast iron are all resistant to most forms of corrosion, but none of them are
elastic. They are not flexible and do not
return to their original shape once deformed.
Nitinol is a titanium–nickel metal
alloy that was first discovered just a few decades ago. It is a smart alloy and is often
described as having shape-memory properties. This means that it will return to
its original shape if it’s deformed. Nitinol alloys are highly resistant
to most forms of corrosion. And they will not deteriorate if
they are put into different parts of the human body. These properties make it ideal to
be used to make stents for blood vessels. Therefore, the correct answer is
(E) nitinol.
