Alloys are used because they are often harder than pure metal. Making alloys usually involves mixing one harder element with a metal to create a stronger item.
Alloys are more commonly used than pure metals due to their increased hardness. This is due to their atom arrangement; in alloys, the atoms are of varying sizes. This makes it difficult for the layers of atoms to move, thus increasing its durability and stability. Pure metals have a more uniform layer of atoms, which also makes the atom layers more vulnerable to movement. Most pure metals are not used in manufacturing due to their softness when compared to alloys.
Some alloys also enhances the properties of the pure metal, increasing its usefulness. For instance, nitinol, which is a mix of nickel and titanium, is able to return to its original shape after being heated.