The material that is easier to use for these electromagnets is a niobium and titanium alloy. This metal alloy has such mechanic properties when it is coated with copper that it can be stretched until we get filaments of a few-micron diameter. The superconducting strand is made of several thousands of these niobium-titanium copper coated filaments. If all the filaments are gathered in a single copper sheathing, we will get a rigid cable as the one in our example. If we gather several smaller strands, we will get a more flexible cable that can take the shape we need, like any copper cable. The copper sheathing is always present around the niobium-titanium alloy to allow the current to flow when the alloy accidentally loses its superconducting capacity. This material that presents so many advantages when it is in the superconducting state becomes extremely resistant when it changes state. It then becomes a matter of emergency to decrease the current of the electromagnet if you do not want it to melt.
The niobium-tin alloy is also widely used, even if its technology is more complicated, because its electromagnetic characteristics are superior to those of niobium-titanium.
